Iodine deficiency in dairy cattle - Anderson PD; Dalir-Naghadeh B; Parkinson TJ (Proceedings of the New Zealand Society of Animal Production, 2007)
Clinical signs of iodine deficiency (e.g. non-visible oestrus, low first service conception rate, stillbirths), plus low (<45 nmol/L) serum thyroxine (T4) concentrations were observed in dairy cows from 12 farms in the Manawatu. Goitre, as determined by diffuse thyroid hyperplasia,plus significantly (p<0.05) increased thyroid size, weight and thyroid:bodyweight ratio, was found in 16% (6 of 38) of stillborn calves from these farms. Goitre was present in calves from 42% (5 of 12) of the herds. One of these farms was chosen to investigate temporal changes in concentrations of the thyroid hormones, thyroxine (T4) and tri-iodothyronine (T3), as an indicator of iodine status, and to attempt to determine the optimum time for sampling. Blood samples were collected from a cohort of animals from the herd (20 representative animals from 400 cows) 8 times over a 12 month period, for measurement of total serum iodine (TSI), T3 and T4 concentrations in both individual cows and pooled (10 cows) samples. T4 was maximal in June (58.6 nmol/L) and lowest (39.2 nmol/L) in October (P<0.05). Between November and Augusts meanTSI varied (NS) from 31 ± 9 to 47 ± 9 µg/L, but was significantly (P<0.01) higher in October (91 ± 16 µg/L). T4 concentrations were(P<0.05) related (r = 0.35) to TSI between November and August (7/8 blood samplings), but were widely divergent (r = 0.08) in October. Concentrations of T3 were unrelated to TSI (r= 0.07). In pooled samples, concentrations of TSI, but not T3 or T4, were closely related to the mean concentrations in individual animals. An iodine-response study was also carried out on the same herd. Half the herd (200 of 400) were given (6 mL i/m) iodised oil (Flexidine, Bomac) before mating and before calving. The pregnancy rate in anoestrous cows treated with iodine was 13.9% higher than in untreated cows. It was concluded that T4 (individual animals) or TSI (pools of 10 cows) give equivalent information about the iodine status of a herd, except in the post calving period. However, the reference range needs to be validated by further response trials.

Johne's Disease : Management of a challenging disease - Griffin JF; Rodgers CR; Liggett SJ; Bell A; Mackintosh CG (Proceedings of the New Zealand Society of Animal Production, 2007)
In the last 20 years Johne’s disease, caused by infection with Mycobacterium paratuberculosis (Map), has emerged as one of the most important bacterial diseases affecting productivity in New Zealand farmed deer. In addition to clinical losses, subclinical infection results in reduced growth rates of young deer, lower reproductive performance and lighter velvet weights. Traditionally, microbial culture of faecal material or gut tissue has been used to confirm the presence of infection. The Disease Research Laboratory has recently developed a refined ELISA test thatmonitors IgG1 antibody (Paralisa) specific for antigens expressed uniquely by M. paratuberculosis. This test has acceptable sensitivity (75-91%) and specificity (>98%) for the detection of subclinically affected animals. The use of this test in severely infected deer herds can reduce the prevalence of reactors from high (>40%) to low levels (<5%) within 2-3 years and result in the elimination of clinical disease. Clinically detectable Johne's disease represents a minor proportion of the total number of animals infected in a herd so it is also important to have diagnostic tests that detect subclinically infected animals. Using the Paralisatest, it is now possible to implement management systems to electively remove infected deer to increase production and reproductive performances.

Landcorp Farming Lecture : Genomic selection for accelerated genetic gain in livestock - Hayes BJ; Goddard ME (Proceedings of the New Zealand Society of Animal Production, 2007)
The sequencing of a number of the livestock genomes and developments in genotyping technology has made it possible to genotype animals for tens of thousands of markers relatively cheaply. Genomic selection exploits this information to calculate genomic breeding values (GEBVs), as the sum of the effects of small chromosome segments across the genome. Effects of chromosome segments are first estimated in a large population with phenotypic information. In subsequentgenerations, only marker information is required to calculate GEBVs. Accuracies of GEBVs calculated for animals with marker information only, can be as high as 0.85. Results from analysis of real data from dairy cattle suggest approximately 30,000 single nucleotide polymorphism markers will be required to calculate GEBVs with maximum accuracy. Chromosome segment effects should be estimated from at least 2000 phenotypic records. A trial of genomic selection in the Australian Holstein population, with 384 bulls typed for 9919 markers, achieved accuracies of GEBVs of up to 0.82, despite sub optimal marker density and limited number of phenotypic records. In dairy cattle, maximum genetic gain using genomic selection will be achieved by selection of young bulls for widespread use without progeny test, allowing a halving of the generation interval.

LoinMAX and MyoMAX : Taking DNA marker tests from the research environment to commercial reality - Campbell AW; McLaren RJ (Proceedings of the New Zealand Society of Animal Production, 2007)
Meat yield is an important component of most sheep breeding programmes. To improve meat yield, breeders use a variety of tools including marker assisted selection (MAS). Ovita funded AgResearch to develop two marker tests to assist in selection for superior meat yield. These have been branded MyoMAX TMand LoinMAX TMand originated from quantitative trait loci (QTL)studies over the past decade. In both cases the development of these commercial marker tests involved refining the QTL locations, identifying informative marker haplotypes and validating these in industry flocks. Both the LoinMAX TMand MyoMAX TMbeta tests were field validated using a numberof commercial breeders. The validation process showed that the phenotypic effects of both LoinMAX TM and MyoMAX TM were significant in different genetic backgrounds and that there were no negative correlations between the presence of LoinMAX T Mand MyoMAX TM with other traits, such as meat quality and growth rate. Both LoinMAX TM and MyoMAX TM have now been successfully commercially launched byCatapult Genetics Ltd and are being widely used in industry.

Maternal constraint in sheep breeds with diverse birth weight - Jenkinson CMC; Kenyon PR; Blair HT; Breier BH; Gluckman PD (Proceedings of the New Zealand Society of Animal Production, 2007)
Reciprocal crosses of Shire and Shetland ponies and transferring embryos between small and large breeds of horses and pigs have shown that maternal size, ratherthan foetal genotype, is the primary determinant of birth size. In the present study, 40 Cheviot (C) ewes and 40 Suffolk (S) ewes were split into two groups. Each group was mated to either two Suffolk rams or two Cheviot rams to generate CC, CS, SC and SS lambs. Birth weights differed significantly (P<0.01) between the four lamb genotypes (CC 4.12 ± 0.21; CS 4.43 ± 0.23; SC 5.08 ± 0.19; SS 5.17 ± 0.19, kg). Furthermore, lower birth weight was significantly (P<0.01) associated with lower maternal circulating plasma placental lactogen (oPL) concentrations in the Cheviot dams at days 90 (C 25.8 ± 10.0 vs. S 71.8 ± 11.6, ng/ml) and 110 (C 84.5 ± 16.8 vs. S 175.9 ± 19.0, ng/ml) but not at day 130 of gestation. These results indicate that the size of the ewe affects the intrauterine development of her lamb. Moreover, the lower concentrations of oPL in the Cheviot dams may have contributed to the constraint observed in foetal growth.

The mechanical properties and lesion score of the sole and white line horn of front and hind claws of heifers prior to and during first lactation - Winkler B; Margerison JK (Proceedings of the New Zealand Society of Animal Production, 2007)
The aim of this experiment was to study the incidence of lameness and the pattern of lesion formation in the sole horn during the pre- and post-partum period of first lactation Holstein Friesian heifers and to compare these to mechanical testing of the hoof horn strength and with the breed society (Holstein Friesian) index of classification for conformation (HUKI) to compare heifers susceptibility to lameness. Samples of sole hoof horn were taken from all claws of 20 heifers at 144 and 40 days pre-partum and 50, 100 and 150 days post-partum. Simultaneously, all claws were assessed for the lesion score in the sole horn. Locomotion score was assessed weekly and heifers were conformation scored for the Holstein UK Index (HUKI). Hoof samples were analysed for elastic modulus and punch resistance. Punch resistance of the sole horn was significantly greater in front claws when compared to hind claws. The punch resistance, elastic modulus, lesion score and locomotion score increased significantly during the post-partum compared with the prepartum period. post-partum elastic modulus and punch resistance were significantly negatively correlated to increase in lesion score and locomotion score between measurement periods and positively correlated to the breed society conformation index (HUKI) score for legs and feet. Mechanical tests reflected the changes in housing and in haemorrhage levels that occurred between 144, 40 pre- and 100 days post-partum and there may be a potential to select animals for increased hoofhorn quality and reduce wearrates during lactation.

Metabolic feed efficiency - opportunities for selection in dairy cows - McNaughton LR; Pryce JE (Proceedings of the New Zealand Society of Animal Production, 2007)
A literature review and simulation study is presented to investigate the potential role of metabolic feed efficiency in dairy cattle breeding programmes. Metabolic efficiency is generally calculated as the difference between actual feed intake and expected feed requirements and as a result is a residual term, hence it is often referred to as residual feed intake (RFI). There is evidence of genetic variation in RFI in poultry, sheep and beef cattle. Heritability estimates inbeef cattle are moderate (0.14 to 0.43). Heritability estimates in dairy cattle range from zero (no genetic variation) to moderate (0.38). RFI is positively genetically correlated with feed intake, so more efficient animals tend to eat less. Information is sparse, but suggests there is no genetic correlation between milk production and RFI. Genetic correlations between health and fertility traits and RFI in cattle have not been established, but evidence frommice and pigs suggests unfavourable correlations between RFI and fertility. Estimating the genetic relationships between RFI and health and fertility in dairy cattle is required. The identification of genetic markers that explain sizeable variation in RFI, or an easily measured correlated trait would be the preferred options to enable selection for RFI in dairy cattle, ideally breeding values for RFI would be estimated and included as part of a multiple-trait selection index.

Monensin controlled release capsules for improved production and mitigating methane in dairy cows fed pasture - Waghorn GC; Clark H; Taufa V; Cavanagh A (Proceedings of the New Zealand Society of Animal Production, 2007)
Mitigation of ruminant methane is an important component of New Zealand’s strategy to lower greenhouse gas emissions. Methods for mitigation must be profitable, easily achievable for producers and be applicable to a wide range of farming systems and topography. The rumen ionophore monensin, is potentially capable of meeting these requirements, but its effects on both production and methanogenesis have been variable with forage diets.A trial was undertaken with 60 lactating Friesian/Holstein dairy cows in early – mid lactation and fed pasture over a 3 month period, to measure effects of a commercially available monensin controlled release capsule (CRC) on milk production, rumen metabolites and methane production. Monensin had no effect on fat or protein yield and therefore milksolids yield, 1.68 kg/day for both groups of cows, was unaffected. Rumen volatile fatty acid ratios, measured in 10 animals, were not affected by monensin treatment and average methane production (323 g/day) was similar for both groups (P=0.961). The absence of benefits from monensin for either production or methane mitigation in dairy cows fed forages as a sole diet are in line with other published data. Monensin CRCs will not provide a profitable route for methane mitigation in ruminants grazed on pasture.

Multiple trait national genetic evaluation for cow longevity - Harris BL; Montgomerie WA (Proceedings of the New Zealand Society of Animal Production, 2007)
In New Zealand genetic evaluation for cow longevitywas based on a single trait model where the phenotypic record was actual or predicted days survived in the milking herd. Cows which were yet to express their actual longevity received a predicted phenotypic record based on the milk production and liveweight production values, traits other than production (TOP), and fertility breeding values. The prediction equation was a proxy for a multiple trait model. At the time of implementation a full multiple trait model was not computationally feasible. A study was undertaken to investigate the feasibility of developing a full multiple trait model. The multiple trait model has the advantage of incorporating the appropriate genetic relationships among the predictor traits and the longevity traits, as well as allowing different genetic correlations among the individual longevity traits. The first stage of the study was to estimate the genetic correlations among all traits under genetic evaluation and two longevity traits; survival from first to second lactation and first to fifth lactation. Data used for genetic correlation estimation was from first lactation records from the Sire Proving Scheme herds for seasons 1987 to 2005. The two fertility traits, 42 day calving rate and percent mated in the first 21 days, had the highest genetic correlations with the longevity traits, ranging from 0.84 to 0.27. Body condition score, management TOP and the milk production traits had moderate genetic correlations with the longevity traits, ranging from 0.42 to 0.24. Somatic cell score, udder support, udder overall, legs, capacity and dairy conformation had low genetic correlations with the longevity traits but were significantly greater than zero. Four longevity traits, and 9 predictor traits were included in a national genetic evaluation for cow longevity. The 9 predictor traits were chosen from the traits that had significant genetic correlations with cow longevity and contained genetic information that was not already included in other predictor traits. Comparisons between sire breeding values from the single trait model and the multiple trait model show good agreement with a correlation of 0.95 for Animal Evaluation enrolled sires. Investigation of the sire breeding values shows that the multiple trait model puts a greater emphasis on cow fertility than the single trait model.

New perspectives on deer reproduction , growth and production efficiency - Stevens DR; Asher GW; Archer JA; Scott IC; Ward JF; O'Neill KT; Corson ID (Proceedings of the New Zealand Society of Animal Production, 2007)
Reproduction and growth intersect during lactation. Lactation is the period when the initial productivity of the calf is expressed and much ofthe potential production efficiency is set. Examples of recent advances in our understanding of productivity systems in deer farming are summarised. Experimentation in lactation has highlighted new information that can improve on-farm production. Recent research has given an understanding of the lactational outputs of the hind rearing either a red or F1 wapiti crossbred calf. Further experimentation has examined the role of protein and energy in determining calf growth. Other research has quantified both hind and calf intake and live weight change during late lactation. The impacts of these developments are discussed.

Parturition duration and birthing difficulty in twin and triplet lambs - Everett-Hincks JM; Dodds KG; Kerslake JI (Proceedings of the New Zealand Society of Animal Production, 2007)
The primary objective of this study was to investigate the relationship between parturition duration, localised oedema in lambs (as determined by post mortem findings) and lamb survival. Parturition behaviour was recorded for 131 mixed age Coopworth ewes and their 303 lambs (twins n=180; triplets n=123). Twin lambs and first born triplet lambs that did not survive tothree weeks of age took at least twice as long to be born than lambs that survived (P<0.05). The duration of parturition for lambs that died and had moderate to severe subcutaneous oedema was more than three times longer than for those that had none and minor localised subcutaneous oedema at post mortem examination (P<0.05). Further research is required to understand the factors contributing to prolonged parturition for twins and triplets. This information is needed so that appropriate management techniques and animal breeding programmes can be developed to reduce birthing difficulties (dystocia) and lamb mortality rates.

Preliminary observations on fresh and healed scars in deer skins - Scobie DR; Pollard JC (Proceedings of the New Zealand Society of Animal Production, 2007)
To improve knowledge of where frequent damage to deer skins was occurring, and how to quantify it, studies were carried out at deer slaughter plants (DSPs) in the South Island, New Zealand. Skins from supplying farms were identified using a pattern punched into the fresh skin. In Part A, scarring was assessed following de-hairing and pickling, in skins from three suppliers at each of five slaughter plants. On average there were 4 (range 0-17) fresh and 7 (range 0-85) healed scars per skin. Effects of supplier and DSP on the number of fresh and healed scars were observed (P<0.001), with some achieving very low levels of damage, and some showing frequent, consistent forms of damage. In Part B, skins were assessed at wet-blue and finished leather stages, from deer killed in nine slaughter groups over three days at one DSP. In wet-blue skins, slaughter groups differed in the number (P<0.001) and severity (P<0.01) of healed scars, while in finished leather, slaughter groups differed significantly in damage score (P<0.05). Together the studies showed effects of supplier and DSP on the amount, severity and type of deer skin damage.

Presidential Address 2006: Females are in fashion - Scobie DR (Proceedings of the New Zealand Society of Animal Production, 2007)
It is with some trepidation that I explore this topic with you. Please bear with me and don’t throw your barbs until the end, when I would imagine there will be at least some of you that I have not offended in one way or another. I don’t seek to upset or embarrass any particular person, but I simply want you to think about what I have to say. Some of the references I use are not the kind of reference you could track down easily, but let us just say that was a protocol brought into science by men, set it to one side and see where a more inclusive style of language might lead us.

Production and physiological indicators to select cows suitable for extended lactations - Kay JK; Aspin PW; Phyn CVC; Roche JR; Kolver ES (Proceedings of the New Zealand Society of Animal Production, 2007)
Individual cows vary in their ability to maintain milk production for an extended lactation. Identifying production and physiological markers to indicate cows suitable for extended lactations would allow dairy farmers to make early decisions to withhold mating of individual cows or to continue milking specific nonpregnant cows through the winter months. Fifty-six genetically divergent overseas and New Zealand Holstein Friesians were allocated to three pasture-based dietary treatments (0, 3 and 6 kg concentrate DM/cow/d) and mating was withheld to target a 670-d lactation. Within each treatment there was little correlation between animal evaluation index values and milksolids (MS) production during the extended lactation period (>296 days in milk; DIM). There was a positive correlation between MS yield from the initial normal season (<296 DIM) and extended lactation MS production; and a negative correlation between body condition score (BCS) at theoretical dry off date (~296 DIM) and extended lactation MS yield. Plasma hormone and metabolite data from wk 1-10 postpartum demonstrated a positive association between nonesterified fatty acid levels and extended lactation MS production, whereas glucose,insulin, and insulin like growth factor-1 were negatively associated with extended lactation MS production. Overall, data indicate that the animal evaluation index is not a good indicator of animals suitable for extended lactation, however normal season milk production, early lactation plasmahormone and metabolite and late lactation BCS data may be useful to identify animals that will undergo a successful extended lactation.

Prospects for genome wide selection in the New Zealand livestock industries - Dodds KG; Amer PR; Spelman RJ; Archer JA; Auvray B (Proceedings of the New Zealand Society of Animal Production, 2007)
A number of DNA marker applications aid genetic selection within subpopulations of New Zealand’s livestock farming industries. Advances in genomic tools have opened the possibility of genotyping individuals for a large set of markers, enough to have a large proportion of the genome ‘tagged’ with at least one of these markers. This creates opportunities for genome wide selection (GWS) – the selection of breeding animals based on very large numbers of marker genotypes. There are a number of requirements for GWS to work, including the existence of genotyping technology to provide genotypes at a sufficient density, tractable statistical methods for estimating marker effects to use in prediction models and suitably phenotyped populations which when genotyped allow estimation of relationships between markers and traits. Additional phenotyped populations are required to validate their predictive ability and demonstrate economic benefits to breeders and to the commercial tier. A high density genotyping platform is available for cattle, but may need further developments. Plans are underway for a similar platform for sheep, but not for deer. The dairy industry is well placed to implement GWS, as there is a large bank of DNA samples of industry sires representing most of the genome variation present. Genotyping these animals will allow marker effects to be estimated and the reduced generation interval arising from selecting young sires should easily overcome any decrease in selection accuracy compared with progeny testing. Industry structures are likely to evolve to allow a return to entities undertaking GWS. GWS will be mostbeneficial for traits with low heritability, that cannot be measured on selected parents and/or that are expensive to measure. Genes of known effect may continue to be accounted for individually, particularly if they exhibit non-additive effects.

Puberty in Angus bulls from lines selected for heifers' age at puberty - Morris CA; Amyes NC (Proceedings of the New Zealand Society of Animal Production, 2007)
In reproductive studies of juveniles, puberty has to bedefined and decisions made on how to record it in both sexes. Our recording criterion for age at puberty in heifers is the date (and hence age) of first behavioural oestrus. This is a heritable trait under New Zealand grazing conditions, with a realised heritability estimate from a long-term AgResearch selection experiment of0.27 ± 0.04. Data published in Edinburgh by R. B. Land suggest that male puberty traits in mammals are also inherited and are related to female puberty traits, but the difficulty is in measuring puberty in males. Our indicator in the selection experiment mentioned above is scrotal circumference (SC), where single SC records had a heritability of 0.40 ± 0.03 and a repeatability over time of 0.67 ± 0.01. Our objective in the present study was to determine whether another indicator might be semen quality, derived from a serial assessment of semen samples over the likely puberty period, and to compare this with serial SC records. The selection experiment was established in 1984/85 with Angus cattle. Genetic selection was applied in one line (‘AGE-’) for lower age at puberty in heifers, and in a second line (‘AGE+’) for greater age at puberty in heifers. SC data were monitored each year in bulls from both lines. Young bulls from the 1997 and 1998 calf crops (25 per year) were also monitored for semen quality from about 9 to12 months of age. Semen samples were obtained by ampullary massage, and quality was assessed on a warmmicroscope stage, using a 0-5 scale. Semen score was plotted against SC from means for each breeding line and month, and the correlations over both lines were 0.98 in 1997 and 0.86 in 1998. The AGE- line was superior to the AGE+ line by 0.81 semen score units (P < 0.001) and by 4.0 cm (14%) in SC (P < 0.001). Results showed that semen quality was associated with SC, and that both had responded to heifer puberty selection. It was easier to measure SC as the male puberty trait.

Quantifying the importance of submission rate to artificial breeding on reproductive performance and profitability in dairy cattle herds - Beukes PC; Tiddy RM; Burke CR; Levy G; Lancaster JAS (Proceedings of the New Zealand Society of Animal Production, 2007)
Dexcel's Whole Farm Model (WFM) allows the user to construct a mating policy using dates for anoestrous treatment, artificial breeding (AB) and bull mating with corresponding levels of heat detection efficiency. The model then predicts the outcome of the mating programme for each individual animal using an approach based on physiological events, represented by algorithms incorporating current best knowledge. Four commercial dairy farms were initialised in WFM by describing the farm set-up and management decisions for the 2005/06 season. A range of feeding, production and reproduction indicators was used to validate the model predictions against that observed. All four farms had an observed 3-week submission rate (SR) of about 90%. An alternative scenario with SR at80% was created for each farm by simulating reduced oestrous detection efficiency during AB. The eight scenarios were then run for 20 random simulations over three consecutive years. The trend was for SR 90% to result in more milksolids in the second and third years, improved reproductive outcomes and, despite higher AB costs, an increased (P<0.05) economic farm surplus of $80+/ha. This exercise demonstrated that the WFM is capable of simulating reproductive performance in dairy herds and holistically linking this performance to productivity and profit over successive seasons.

Reconciling the differences between the length at which lambs' tails are commonly docked and animal welfare recommendations - Fisher MW; Gregory NG (Proceedings of the New Zealand Society of Animal Production, 2007)
The rationale for the length at which lambs’ tails are docked was investigated by comparing lambs with No-tail, Short, Medium (covering the vulva in ewe lambs and at a similar length in males), Long, and Undocked tails. In Experiment 1, dagging and shearing required additional effort in Long and Undocked animals. There were no differences in average dag scores, but few lambs had dags. Shorter tail docking resulted in significantly (P<0.05) lighter recto-coccygeal muscles (from 8.9 ± 0.5g in Undocked to 6.6 ±0.4g in No-tail). The tail stumps of half of the No-tail, Short and Medium showed evidence of neuroma development and degenerative nerve changes compared with few of the Long and Undocked lambs. In Experiment 2, restlessness, an indicator of pain and distress in rubber ring docked lambs, tended to be more pronounced the shorter the tail was docked. Experiment 3 compared typical farm practices (Short), with the AWAC-recommended length (Medium). The slightly longer length was associated with (1) more lambs difficult to dag (11/44 Medium vs. 4/44 Short; P<0.001); and (2) no perceived benefits in increasing tail length. While the traditional Short and Medium tails appear to be the most appropriate, pain and distress, neuroma development and rectal muscle function may also be affected by tail length. It is yet to be determined if these additional factors justify a change to current practicesbut that possibility is considered unlikely.

Regulation of milk protein synthesis in the bovine mammary gland : A proteomic approach - Smolenski G; Bond JJ; Wheeler TT; Roy NC; McNabb WC; McCoard SA (Proceedings of the New Zealand Society of Animal Production, 2007)
The molecular mechanisms that regulate milk protein synthesis in the dairy cow are not well understood. We used a proteomic approach to identify potential regulators of milk protein synthesis among the endoplasmic reticulum (ER) proteins. Mammary tissue was collected from mid-lactation dairy cows treated with atropine (Atr; decreased milk production), growthhormone (GH; increased milk production) or vehicle alone. Fractions enriched for ER associated proteins were prepared by differential centrifugation and then resolved by 2-dimensional electrophoresis (2-DE). Proteins were visualised using colloidal coomassie G-250 and the phosphor-protein specific stain, Pro-Q Diamond. We identified 4 significant (P<0.05) and 9 marginally significant (P<0.15) spots that were differentially expressed between treatment groups. Six spots were subjected to LTQ ion trap tandem mass spectrometry and 2 proteins were identified with a high level of confidence: major vault protein (MVP) (27% of the control level after GH treatment, P<0.05), and heat shock 70Kda protein 8 (HSPA8) (41% of the control level after Atr treatment, P <0.01). Western blotting showed a 24% decrease in HSPA8 following Atr treatment (P<0.10) and a 55% decrease in MVP following GH treatment (P<0.10). These results provide a focus for further investigation of the role of MVP and HSPA8 in influencing milk production.

Response of calves to different levels of mixed species gastrointestinal parasite infection - Burggraaf VT; Puha MR (Proceedings of the New Zealand Society of Animal Production, 2007)
The effect of different levels of parasite infection was studied in 5-month old calves. Eighty-four calves were dosed with 0, 1000, 2000, 4000, 7000 or 10000 parasite larvae (L3) per day for 6 weeks (90% Cooperia, 10% other species), or were drenched 3-weekly, whilst grazing in one mob. Worm burdens were then determined in 3 calves per treatment. The remaining calves then grazed together for 11 weeks to determine carryover effects, during which they were all drenched at weeks 5 and 9. At the end of L3 dosing, there were no liveweight differences, but by week 5 of the carryover period, calves receiving 10000 L3 per day were 12 kg lighter than drenched or 0 L3 calves (P<0.05). This difference was maintained for the rest of the experiment. Cooperiaburdens (76000/calf) in 10000 L3 calves were at least double those on all other treatments (P<0.001). There was no relationship between L3 dose and worm burden for the other parasite species, or L3 dose and faecal egg count. This experiment has shown that for calves dosed with less than 10000 L3 per day, drenching does not increase liveweight gain when the parasite larvae are 90% Cooperia.

Responses to selection in ryegrass staggers lines of sheep - Morris CA; Amyes NC; Orchard RL (Proceedings of the New Zealand Society of Animal Production, 2007)
Ryegrass Staggers (RGS) is predominantly a summer/autumn metabolic disorder in ruminants, caused by ingestion of the lolitrem-B toxin from endophyte-infected perennial ryegrass, and it is common in New Zealand. It causes lack of neuromuscular co-ordination in susceptible animals under stress, e.g. when mustered by sheep dogs. It is of welfare concern, and it is costly to farmers because it severely compromises grazing management. A flock was established at AgResearch in 1993, with two lines bred for resistance (RGS-R) or susceptibility (RGS-S) to RGS. Lambs are scored for susceptibility each year, when grazing on high endophyte pastures, and mustered by sheep dogs. In 2005 and 2006, 94% and 91% of lambs respectively in the RGS-S line showed clinical staggers, when grazing together with the RGS-R line which had 2% and 6.5% of clinical cases, respectively (P < 0.001). Using the latest standardised RGS scoring system, the heritability estimate of resistance/susceptibility to RGS was 0.36 ± 0.04. To understand more about why and how the RGS lines differ, blood samples were taken from the breeding-ewe flock (n = 126) in June 2005, outside the usual RGS and facial eczema season. Compared with the RGS-R line, the RGS-S line ewes had a 23% higher activity (P < 0.001) of aspartate transaminase (AST), an enzyme indicating hepatic or muscular damage; there were similar findings inewes sampled four weeks apart (between-animal repeatability for AST = 0.85). In plasma samples from selection-line yearling females (two birth years; n = 95), the RGS-S line had 27% and 37% higher AST and alanine transaminase activities, respectively (both P < 0.001), and a 38% higher creatine kinase activity (P < 0.05) than the RGS-R line. One explanation of these results is that, compared with the RGS-R line, selection in the RGS-S line may have changed two functions, a reduced ability to detoxify lolitrem-B, and an increased sensitivity to stress expressed as a tendency to show increased muscle tetany and damage.

Restricted postpartum feeding in grazing dairy heifers decreases milk production but does not lengthen oestrous interval - Chagas LM; Gore PJS; MacDonald KA; Blache D (Proceedings of the New Zealand Society of Animal Production, 2007)
The aim of this study was to determine the effects of pasture allowance postpartum on the initiation of ovarian activity, metabolite and hormonal secretion, and milk production. After calving, thirty six HolsteinFriesian heifers (BCS 5.0) received either unrestricted pasture allowance (UNR; n=18) or restricted (RES; 73% dry matter intake of the unrestricted group;n=18) pasture allowance. The LW was lower (P < 0.05) for the RES group than the UNR group. Body condition score of all heifers decreased after calving in both groups. The mean time to ovulation was similar for UNR 50.0 and RES 50.3 sed. 8.2 days after individual calving date. The daily average from week 2 for milksolids, protein and lactose yield was lower (P < 0.05) in the RES group. Plasma concentrations of insulin were lower (P = 0.0085) in the RES group when compared to the UNR group. Glucose concentrations was lower (P = 0.016) in the RES group. Plasma concentration of NEFA was greater (P = 0.001) in the RES group. There was an interaction with treatment differences decreasing by week 11 and 12 for glucose (P =0.001) and NEFA (P =0.006). Plasma concentrations of leptin (P = 0.013) and IGF-I (P = 0.026) were lower in the RES. No differences, associated with postpartum nutrition, were found for plasma GH. Restricted feeding postpartum had no effect on days to first postpartum ovulation but decreased liveweight, milk production and affected some metabolic hormones during postpartum.

Semen parameters of cloned bulls - Smith JF; McDonald RM; Wells DN; Cox NR (Proceedings of the New Zealand Society of Animal Production, 2007)
Bulls cloned from the somatic cells of genetically elite sires can make a major contribution to genetic improvement and the rate of dissemination of improved genetics within both the dairy and beef industries. However, little is known about the physiology of clone males and the quality of their semen in particular. This paper reports on the semen characteristics of five cloned Friesian bulls, compared to the two ‘Donor’ bulls from which three and two of the clones were derived by nuclear transfer, respectively, and an age matched control bull. Three batches of frozen semen from each of these eight bulls were obtained from a commercial AB centre and analysed. Four straws from each batch of semen were thawed, pooled and made up to 1mL with RSD-1 diluent and sub-samples taken to evaluate viability, motility, morphology, migration (using a synthetic mucus) and DNA damage. Viability, motility and migration assays were performed immediately after thawing (0 hours) and repeated after 3 hours of incubation at 38°C. An additional straw from each semen batch was used to determine sperm concentration and proportion of diploid cells. There were significant differences (P<0.05)between individual bulls in all parameters except diploid cells (0.16 ± 0.05 %), sperm DNA damage (4.41 ± 1.13%) and normal sperm (93.3 ± 6.7%). The differences in viability (range 74.9 to 54.9% at 0 hours; 49.6 to 22.5% at 3 hours), motility (59.2 to 28.3%; 52.5 to 29.2%) and migration (vanguard distance 68.3 to 42.5 mm; 38.8 to 12.5mm and running distance (>150 sperm) 33.3 to 23.3mm; 20.4 to 6.7mm) were greater at 3 hours than at0 hours reflecting individual variation in rate of change in parameters over time. However, examination of the variation between clones within a clonal family or line and between lines revealed that this was similar to the overall individual variation, indicating that members of a clonal family are not more uniform. Nonetheless, these results indicate that the samples of semen from the cloned bulls were as good as those of the original donor bulls and fit for commercial use to potentially disseminate elite genotypes.

Sperm DNA damage after scrotal insulation in rams - McDonald RM; Smith JF; Montgomery GW; Fleming JS; Cox NR (Proceedings of the New Zealand Society of Animal Production, 2007)
Human male fertility is in decline and one reason given for this is the increased incidence of sperm showing chromosomal or DNA damage. Previous work in laboratory and farm animals as well as humans has shown that elevated testicular temperatures increases the incidence of sperm with DNA damage. As part of a study into the effect of temperature on mutation rate in spermatozoa using rams as a model, measurements of sperm DNA damage were also recorded. Twelve mature Dorset x Romney rams, were trained to AV semen collection. Scrotal insulation harnesses were applied (plastic bag with cotton wool insulation inside a rubberised fabric protection cover) to two groups of 6 rams for either a 24 or 48 hour period at day 0. Semen was collected on days -4 and 0 as control samples for each ram before treatment and days 3, 7, 10, 14, 17, 21, 24, 28, 31, 35, 38, 43, 45 and 49 post treatment. Semen was diluted in RSD-1 + TNE and snap frozen in liquid nitrogen. Samples were thawed and assessed by the Sperm Chromatin Structure Assay (SCSA) on the flow cytometer. This measures sperm susceptibility to ‘in situ’ acid denaturation by staining with acridine orange fluorochrome, which fluoresces differentially when binding to double stranded DNA (green) or single stranded DNA (red). The data indicate an increase in the percentage of sperm that have DNA damage, appearing about 21 days post treatment and reaching a maximum at 35 days. The proportion of sperm with moderate to highlevels of DNA damage was significantly (P<0.001) greater in the 48 hour treatment group and was still observed at 49 days while most of the 24 hour treated animals had recovered by this stage. Of particular interest was the shift of the entire sperm population, in DNA fragmentation index (ratio of red fluorescence:total (red + green) fluorescence), indicating increased susceptibility of DNA denaturation in all cells. This was accompanied by an increase in DNA stainability (increase of green fluorescence) which is interpreted asbeing due to an increase in the number of immature sperm cells with less compacted chromatin which results from abnormal or unprocessed protamines. The sperm damage seen after a relatively mild heat treatment indicates possible mechanisms for the adverse effects of modern life styles on male fertility.

Strain differences in Merinos for carcass and meat quality - Hopkins DL; Mortimer SI; Stanley DF; McMillan DC; Anderson SL (Proceedings of the New Zealand Society of Animal Production, 2007)
The increased emphasis on the Merino for meat production has heightened the need to quantify the variation across the breed for meat and carcase traits and to produce geneticcorrelations and heritabilities for these traits. This paper reports on strain effects (broad, medium and fine wool) on carcase and meat quality traits for 1934 rams. Rams (~19 months of age) were slaughtered over 4 years and data on animals from 272 sires were collected. Every year, the rams were fed a formulated pellet at pasture for 5 weeks before slaughter. All animals were slaughtered in commercial abattoirs. Hot carcase weights were recorded and the GR measured using a GR knife. After overnight chilling (4–5°C), carcases were cut between the 12th/13th ribs and the longissimus thoracis et lumborum (LL) was exposed to the air at chiller temperature for 30 min. Meat colour was measured on the cut surface using a Minolta Chromameter set on the L*, a*, b* system. The pH of the LL and the semitendinosus (ST) muscle was also measured. Fine wool rams were the fattest when compared at the same carcase weight. The broad wool strain had the lowest pH in both muscles and there were minimal differences between strains for meat colour. These real differences between Merino strains in meat quality traits require more detailed investigation in order to understand their biological bases and identify if potential markers exist that could be used in Merino breeding programs.

Summer lamb finishing on forage crops - Lindsay CL; Kemp PD; Kenyon PR; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2007)
The objective of this study was to compare lamb growth and performance on three forages over summer in a large scale, replicated experiment. The three forage treatments were new spring-sown pasture (cv.Bealey perennial ryegrass and cv.Apex white clover), hybrid leafy turnip (cv.Hunter), and a predominant white clover sward. The study was conducted over 28 days, with 28 days preceding the study as the herbage adjustment period. Entire male lambs (n=270) were allocated to one of the three treatments, balanced for live weight at day -28 (D-28). Live weights and liveweightgains were measured at D-28, -14, 0, 14 and 28. Herbage heights were measured pre- and post-grazing toensure lambs were receiving a herbage allowance of at least three times their potential intake. Herbage quality parameters were also measured post-grazing. Liveweight gains were different (P<0.05) between treatment groups, being 311±10.2, 222±10.1, and 160±10.2 g/day for clover, Hunter, and new pasture, respectively. The results showed that Hunter and clover produced superior lamb growth compared to new pasture over summer for the 28 day trial period.

Supplemental fumarate has little effect on the detailed composition of bovine milk during early lactation - Turner S-A; Aspin PW; Kolver ES (Proceedings of the New Zealand Society of Animal Production, 2007)
Future farming practices need to be assessed by the dairy industry for any impacts they may have on the detailed composition and processability of milk. These impacts may change the milk price a farmer receives and the milk processability,product range and product quality. The use of sodium fumarate (an organic acid) to reduce methane production from dairy cows has previously been reported. This experiment investigated the effect of intra-ruminal infusions of sodium fumarate on the detailed composition of milk from dairy cows. Fumarate (5% of daily dry matter intake) was infused into 8 lactating cows while 8 cows received infusions of water as a control. Milksamples were collected during a covariate period, then again following a 16-day treatment period, of which cows were housed indoors for the last 9 days. Gross composition of milk and other production parameters have been presented previously. Milk yield, fat and protein were not affected but lactose concentrations were significantly higher in the milk of cows receiving the fumarate. In the current study, none of the individual casein proteinsmeasured showed an effect of treatment. Of the whey proteins examined, concentrations of α-lactalbumin (α-La) were higher (1.07 vs. 0.98 mg/mL; sed 0.038; P < 0.05) and bovine serum albumin (BSA) concentrations were lower (214.6 vs. 251.0 mg/L; sed 15.1; P < 0.05) in the milk of cows receiving fumarate. None of the individual fatty acids or minerals examined showed a treatment effect. The addition of sodium fumarate to the diet of dairy cows in early lactation does not have a major influence on the composition of milk, suggesting that the product could be used with minimal impact on milk composition and product quality at this early stage of lactation.

Teat spraying before calving and Streptococcus uberis clinical mastitis in heifers : Brief Communication - Lopez-Benavides MG; Williamson JH; Lacy-Hulbert SJ (Proceedings of the New Zealand Society of Animal Production, 2007)
Mastitis caused by the environmental pathogen Streptococcus uberisis a significant problem for New Zealand dairy farmers. Previous work on teat-spraying heifers three times a week for three weeks prior to calving demonstrated that a decrease in S. uberisteat-end contamination reduced the proportion of quarters infected with S. uberisat calving. This study evaluated the effect of teat-spraying heifers in the dry period for its ability to reduce S. uberisclinical mastitis (CM) after calving. Heifers from five commercial dairy herds (n=343) and one research farm (n=54) were enrolled to the study. Half of the animals from each herd were assigned to a Sprayed and the other half to a Not Sprayed group. Both groups were brought to the dairy three times a week, beginning three weeks prior to predicted calving dates and heifers in the Sprayed group were teat-sprayed with a commercially available iodine-basedteat sanitizer. Cases of CM that occurred in the week after calving were sampled and submitted for bacteriological analysis. Incidence of S. uberisCM was 50% lower in the Sprayed, affecting 3.6% heifers vs. 7.4% heifers of the Not Sprayed group (P=0.085). There was an indication that teat-spraying heifers three weeks prior to calving may have positive benefits in the reduction of CM caused by S. uberisafter calving.

Test-day model for national genetic evaluation of milk production traits - Harris BL; Winkelman AM; Johnson DL; Montgomerie WA (Proceedings of the New Zealand Society of Animal Production, 2007)
Genetic evaluation for milk, fat and protein yields, using 270-day lactation yields in an across-breed animal model (AM), has been performed in New Zealand since 1996. A new system has been developed to calculate breeding values from herd-test data. In the current AM, a 270-day lactation yield record is calculated based on 1 to 10 test-day records. The environmental effect of herd-test-day (HTD) is removed during the 270-day lactation yield calculation. However, this is done outside the AM, without reference to the genetic level of the HTD contemporary group. A test-day model (TDM) can simultaneously account for the fixed effects such as HTD contemporary groups,and the genetic, permanent environmental (PE) and temporary environmental randomeffects that affect the trait. By including the effect in the model, the TDM allows the environment specific to each test-day to be better taken into account, resulting in an improved accuracy of evaluation. A TDM can accommodate changes in the genetic and PE effects over time by fitting polynomials of time to these effects. A random regression (RR) TDM can accommodate changes in the genetic and PE effects overtime by fitting Legendre polynomials of days in milk (DIM) to these random effects. The RR TDM allows each cow's lactation curve to have a different shape. TDM evaluations are more stable than evaluations obtained using 270-day lactations because they account for genetic differences in maturity rate and persistency of lactation. The sire breeding values (BVs) from the TDM were compared to those from the AM. For sires with more than 30 daughters, the correlations between the BVs from the two models were 0.990, 0.988 and 0.990 for milk, fat and protein yields, respectively. The TDM demonstrated improved stability for sires undergoing their widespread proof. There was less variation in the change in BVs for reproof sires from August through to October compared to the AM. The sires that show the greatest change during early reproof under the AM were sires that were outliers for their TDM persistency breeding values for their breed.

Testing glutathione-S-transferase for an association with facial eczema resistance in cattle - Morris CA; Cullen NG; Munday R (Proceedings of the New Zealand Society of Animal Production, 2007)
Resistance to facial eczema (FE) in cattle is known to be a heritable trait. The commonly used indicators of susceptibility in affected groups of animals are gamma glutamyl-transferase (GGT) and glutamate dehydrogenase (GDH), which indicate the severity of the liver injury associated with FE. Published research using mouse models suggests that glutathione-S-transferase (GST) may be a downstream indicator of variation in FE susceptibility, and a study was carried outin calves to test this. Friesian-sired and Jerseysired bull calves were purchased from dairy herds in spring 2004, artificially reared from about four days of age, weaned at 75-80 kg, monitored for base-line GGT activity in blood, and then dosed orally with sporidesmin. At 14 and 21 days after dosing, blood samples were taken to measure the activities of both GDH and GGT. A sample of 45 Friesian calves and 45 Jersey calves from the high and low outliers (using GDH activity within breed, 14 days after dosing) wereblood-sampled 15 or 16 days after dosing and measured for GST activity, with 20-25 animals sampled each day, in balanced groups. There were significant differences in GST activity between high and low GDH groups (P < 0.01), and the pooled within-analysisday regression of GST activity on logGGT activity (day21) was negative (P < 0.05). Results confirmed that low erythrocytic GST activity is an indicator of FEsusceptibility, although the differences seen between resistant and susceptible animals are insufficient for use as a predictive tool.

To wether - short scrotum or leave lambs as entire rams ? Revisiting an old question using new genetics - PL Johnson; Kenyon PR; Burnham DL; West DM (Proceedings of the New Zealand Society of Animal Production, 2007)
A comparison of wethers (WTH), short scrotum (SSC) and rams (RAM) was made on 552 7/16 Romney, 3/16 Poll Dorset, 3/16 Texel and 3/16 East Friesianlambs. Lambs were drafted for slaughter using commercial criteria on weight and condition score at weaning (D81), D120, D154 and D192. Due to faster growth rates, by the end of the 2nd kill (D120) approximately 31% of RAM and SSC lambs were slaughtered compared with 16% of WTH lambs (P<0.01), although the difference was no longer significant by the end of the 4 th kill. The carcass weight of WTH (17.6kg) was significantly heavier (P<0.01)than the RAM (17.2kg) but not significantly different to the SSC (17.5kg), despite similar kill liveweights, due to the increased dressing out percentages of the WTH lambs (43.6%, 43.1% and 42.5% respectively; P<0.05). Based on GR, 8.7% of WTH carcasses graded overfat, compared with only 0.6% of RAM and SSC carcasses (P<0.001). Over the kill period the price schedule ($/kg carcass weight) dropped, so for the WTH given their longer time to slaughter and poorer grading due to over fat carcasses the price for WTH carcasses ($49.16) was lower (P<0.01) than RAM or SSC carcasses ($50.37 and $50.70). When the added cost of feeding and drenching was taken into consideration, the net value of the WTH was evenless. Composite wether lambs of still potentially present an opportunity cost, except incertain situations where the management benefits outweigh the direct financial cost.

Ultrasonic measurement of backfat and muscling in sheep selected for parasite-related traits - Wheeler M; Morris CA; Bisset SA; Vlassoff A; Mackay AD; West CJ; Devantier BP (Proceedings of the New Zealand Society of Animal Production, 2007)
This paper reports on backfat depth and muscling comparisons of sheep selected for nematode parasiterelated traits. Results are from two AgResearch projects, the first located at Kaitoke Farm (Upper Hutt), in which experimental Romney lines wereselectively bred for susceptibility (S) or resistance (R) to nematode infection (high or low faecal egg count), or for resilience to nematode challenge whilst maintaining acceptable growth with minimal anthelmintic treatment (RL line); these lines grazed alongside an unselected control line (C). The second project was located at Ballantrae (Northern Wairarapa), in which Romney breeding lines were selected for resilience, with two replicate farmlets under 'Conventional' parasite management (with anthelmintic treatment), and with two further replicate farmlets under 'Low-Chemical' management. The four replicate lines at Ballantrae were serviced by rams of equivalent genetics, from elite RL-line sires bred at Kaitoke or Ballantrae. Ultrasonic backfat depth and eye muscle dimensions (length, depth and area) of ewe lambs from each project were assessed at 8-9 months of age (234 C-, S-, R- and RLline lambs born in 2003 at Kaitoke, and 154 resilient lambs born in 2004 at Ballantrae). Adjustments were made for significant fixed effects including covariate adjustment for live weight. No significant differences were found among the R, C and RL lines for either trait, but the S line had 5-10% smaller eye-muscle dimensions (P < 0.05) than the other lines following an extended period of natural nematode challenge with minimal drench treatment. The two replicate lines under Low-Chemical management were 3.8 ± 0.6 kg (11.8%) lighter in May than the replicates under Conventional management (P < 0.001). After adjustment for live weight, lambs in the Conventional treatments had 15% larger eye-muscle areas (P < 0.001) but not backfat depths than those in the Low-Chemical treatments. Results suggest that muscle dimensions of the Sline lambs were more affected than those of their R-line counterparts by parasite infection, whilst the C-, R- and RL-line lambs did not differ significantly. At Ballantrae, even at equivalent live weights, the two Conventional replicates had more muscling but not fat depth than the two Low-Chemical replicates.

Uptake of DNA testing by the livestock industries of New Zealand - Crawford AM; Anderson RM; McEwan KM (Proceedings of the New Zealand Society of Animal Production, 2007)
This paper describes, from the perspective of the main animal genotyping service laboratory, the uptake of DNA tests by the New Zealand livestock industries. We describe a rapid increase in the use of DNA testing over the last 3-4 years in New Zealand. In particular pedigree establishment and verification has shown significant uptake by deer, cattle and sheep breeders. The highest penetration of DNA testing has been in the deer industry where we estimate 30-40% of the recorded breeding population uses DNA testing to establish and verify pedigrees. The increases have mainly been due to an increase in the number of samples per client rather than an increase in the number of clients using the service.

The use of diazepam as a pharmacological method for evaluating anxiety in sheep - Stewart M; Webster JR; Dowling SK; Stafford KJ; Huddart FJ (Proceedings of the New Zealand Society of Animal Production, 2007)
The aim of this study was to examine the effects of diazepam, an anti-anxiety drug, on the fear responses of sheep and its usefulness as a pharmacological method to study welfare. Fourteen, eight month old Romney ewes were randomly assigned to two treatments and injected via jugular venepuncture with diazepam (0.37mg/kg) or saline (controls) 20 minutes before exposure to a barking dog. Heart rate (bpm) and escape attempts were recorded throughout a 10 minute period before injection (baseline), 20 minutes post injection and 15 minutes following the dog. Average heart rate was lower in diazepam-treated sheep during the first 5 minutes following injection (P<0.01) and was significantly higher (P<0.01) for both diazepam and saline-treated sheep during the 5 minutes following exposure to the dog compared to baseline (+23.1 and +21.5 bpm for diazepam and saline respectively). Heart rate then decreased back to baseline levels during the last 10 minutes. Diazepam-treated sheep tended to have a higher number of escape attempts during the 5 minutes following exposure to the dog (P=0.08) compared to controls, suggesting that diazepam may have paradoxically increased anxiety in some sheep. The lack of differences between treatments suggests that diazepam did not modify the fear response of sheep to a dog. There appear to be interpretive difficulties associated with dose rates and the appropriate fear model in the use of diazepam to study anxiety in sheep.

The use of neural networks to detect minor and major pathogens that cause bovine mastitis - Hassan KJ; Samarasinghe S; Lopez-Benavides MG (Proceedings of the New Zealand Society of Animal Production, 2007)
Bovine mastitis is caused by a diverse range of bacteria, broadly categorised as major or minor pathogens. The objective of this research was to develop an unsupervised neural network (USNN) model for detecting major and minor bacterial pathogens present in milk, based on changes in milk parameters associated with mastitis. A database of 4852 quarter milk samples with records for milk parameters and bacteriological status was used to train and validate the USNN model. Correlations (P<0.05) were found between the infection status of a quarter and its somatic cell score (SCS, 0.86), electrical resistance index (ERI, -0.59) and protein percentage (PP, 0.33). Due to significant multicolinearity, the original variables were decorrelated using principle component analysis. Sensitivity of the model for correctly detecting major and minor infections was 80% and 89%, respectively. Specificity of the model for correctly detecting non-infected cases was 97%. The model is able to differentiate infected milk from non-infected based on milk parameters associated with mastitis. It is concluded that the USNN model can be developed and incorporated into milking machines to provide a reliable basis for mastitis control.

Validation of a technology for objectively measuring behaviour in dairy cows and its application for oestrous detection - McGowan JE; Burke CR; Jago JG (Proceedings of the New Zealand Society of Animal Production, 2007)
Devices (IceTag®ActivityMonitor) using accelerometer technology to determine the behaviour of cows (proportion of time lying, standing, active and step count) were attached to 15 cows (2 per cow) and validated between devices and against observed behaviour. For standing and active, 95% of paired (within cow) one minute data points were within 7% points, 95% of the lying data points were within 1% point, and 95% of stepping data were within 3 steps. The device recorded 100% of lying bouts within ±1 minute of visually observed data. In a second experiment, 16 lactating dairy cows were fitted with IceTag®s and the relationship between behaviour profiles and oestrus evaluated. Blood progesterone concentration and twicedaily visual observations were used to identify precisely ovulation events and four algorithms, based on active and lying behaviour, were developed. A 24 hour rolling mean of activity and a slope threshold of 0.2 calculated for either the previous 10 hours (Activity24/10) or 5 hours (Activity24/5) correctly identified 93% of oestrous events, with 21% and 18% false positive alerts, respectively. Two further algorithms, Lying<20% or Active>5.5% between midnight and 05:00hrs identified 50% and 64% of oestrous events, with 36% and 18% false positive alerts, respectively. In a third experiment using 30 cows, 56 oestrous events were identified through milk progesterone profiles and visual observation. Algorithm Activity24/10 and Activity24/5 identified 84% and 76% of oestrous events respectively. The IceTag®accurately recorded several types of cattle behaviour suggesting useful applications as both a research and industry tool.

Variation of fibre characteristics important in processing, over the body of Australian brushtail possum ( Trichosurus vulpecula ) - Reid TC; Causer SM; Urquhart RA; Woods JL (Proceedings of the New Zealand Society of Animal Production, 2007)
The amounts of fur and processing properties of fur from the Australian Brushtail Possum (Trichosurus vulpecula) were determined. The amounts of fur per animal ranged from 18 – 94 g depending on the sizes of the animals, with 75% coming from the body, 10 - 151% from each of the belly and tail. Fur from the belly was shorter and finer than that from the body, which was shorter and finer than that from the tail (20.1 vs. 27.1 vs. 37.9 mm; 16.2 vs. 17.7 vs. 22.9 µm respectively (P < 0.001). Belly fur was less curved than body or tail fur (47.2 vs. 52.8 and 55.6 °/mm respectively (P < 0.001)). The fibre curvature of fur from all three body sites was half to two thirds of the curvature expected for Merino wool of similar diameter. Coefficients of variation of both fibre length and fibre diameter were approximately double those normally observed in Merino wool (coefficient of variation (CV) = 32.8% (length) and 47.6% (diameter)). The number of medullated fibres was high (mean = 44.5% by weight), with most of the coarser fibres being medullated. The cuticle scale structure was smoother than Merino wool. The high degree of medullation observed contributes to the reported high insulation value of the fur as it results in a high number of fibres for the weight. The relatively low curvature and low scale profile, give the fibre a smooth, slippery surface. This makes processing difficult and causes problems for fibre retention in fabric.

Variation of wool characteristics across the body of New Zealand Wiltshire sheep - Craven AJ; Ashby MG; Scobie DR; Nixon AJ (Proceedings of the New Zealand Society of Animal Production, 2007)
Variations in wool quality within a sheep arise from inherent differences between sites across the body and between fibres within a site, as well as variationsalong individual fibres that result from nutritional, reproductive and seasonal influences. The Wiltshire sheep is a shedding breed in which there is renewed interest due to the relative values of meat and wool, and the costs of wool production. Staple length, fibre diameter, fibre diameter standard deviation, and medullation were measured on wool grown at seventeen sites across the body of two-tooth Wiltshire rams undergoing a photoperiod-induced wool growth cycle. Staple length was longest on the shoulder (41 ± 2.5 mm) and shortest on the belly (14 ± 1.2 mm). There was an inverse correlation between staple length and fibre diameter with the finest fibres on the shoulder and coarsest on the hip (R²=-0.7, P<0.001). This gradient of increasing fibre diameter was associated with increased variation within-staples (R²=-0.8, P<0.001). Fibre medullation increased from the shoulder to the hip. Short coarse fibres on the front and back legs, along with facial hairs highlight differences in major regional skin domains that are established in utero. Although midside samples were representative for each fleece they did not portray the anterior/posterior and dorsal/ventral gradients observed in all characteristics studied. Understanding the within-fleece variation in wool characteristics is a requirement for producing sheep with more desirable fleece distribution patterns.

Apparent digestibility and rumen fermentation of fresh plantain (Plantago lanceolata cv Ceres Tonic) and perennial ryegrass (Lolium perenne cv Nui) - based pasture fed to red deer (Cervus elaphus) - Swainson NM; Hoskin SO (Proceedings of the New Zealand Society of Animal Production, 2006)
The aim of this study was to compare the apparent digestibility and rumen fermentation products in deer fed plantain (Plantago lanceolata) and perennial ryegrass-based pasture (Lolium perenne) during spring. Forages were cut and fed fresh in a cross-over design to seven castrated, rumen fistulated red deer (Cervus elaphus) housed individually indoors in metabolism crates. Plantain contained greater levels of organic matter and lignin and had a greater ratio of readily fermentable to structural carbohydrates and lower levels of crude protein (P < 0.01), compared with ryegrass-based pasture. The apparent digestibility of organic matter for both forages was high, but less for plantain (74.9%) compared with ryegrass-based pasture (81.5%) (P < 0.01). The ammonia concentration of rumen fluid from deer fed plantain (4.6 mmol/L) was less compared with fluid from deer fed ryegrass-based pasture (20.9 mmol/L) (P < 0.01). The apparent reduction in degradation of protein to ammonia in the rumen of deer fed plantain may have implications for increasing the efficiency of use of dietary protein in grazing ruminants. Further research is required to investigate the effect of feeding plantain, and its secondary compounds, on the rumen microbial ecosystem and rumen fermentation.

Artificial rearing of lambs - avoiding abomasal bloat - Bull C; Binnie B (Proceedings of the New Zealand Society of Animal Production, 2006)
Triplets occur when lambing percentages exceed 130%. When triplets are left with their dam, survival is often less than 75%. Artificial rearing of one lamb from each set of triplets offers the chance to increase survival rates. But experience to date has frequently resulted in death rates of 10% to 30% of lambs. On the author’s farm about 100 sets of triplets are born each year. In 2002 an artificial rearing system was put in place based on the Poukawa system. The smallest triplet from each set was removed for artificial rearing. In 2002 and 2003, when lambs were 3 to 5 weeks old, up to 25% died. A worldwide information search suggested that the disorder was possibly abomasal bloat. A Norwegian method of preparing "soured" milk replacer that had been demonstrated to limit abomasal bloat was adapted for New Zealand conditions. Lambs are fed cow colostrum for two days, followed by ad lib. cold "soured" whole milk replacer and ad lib. meal. In 2004 and 2005, there have been no deaths due to abomasal bloat. Total deaths from 199 lambs have been 9. Live weight gains of the lambs have been 220-250 grams per day till 8 weeks.

The biological basis of variation in sheep's fleece cover - Scobie DR; Nixon AJ; Rufaut NW (Proceedings of the New Zealand Society of Animal Production, 2006)
Selective breeding has been used for thousands of years to improve the quality and weight of wool, but surprisingly there is still a large amount of geneticvariation present at the loci involved in the “blueprint” for wool synthesis. This genetic heterogeneity results in considerable variation within, and between individual fleeces. This has both positive and negative implications. Where a wool processor requires uniformity in raw stock, both to gain efficiency in processing and to make a product to specification, it has a negative effect. Where specific traits convey unique properties it opens up opportunities for differentiated products. Markers for genes or knowledge of individual gene effects may be useful for identifying sheep with desirable wool traits that are difficult or expensive to measure under field conditions. The discovery of genetic variation in valuable fibre traits could allow the development of gene-marker tests which would assist breeding for more consistent wool.

Body condition score as a candidate trait in the breeding worth dairy index - Pryce JE; Harris BL; Johnson DL; Montgomerie WA (Proceedings of the New Zealand Society of Animal Production, 2006)
Body condition score (BCS) has been proposed for inclusion in the New Zealand national dairy index, Breeding Worth (BW), to account for replenishment of body tissue. Currently, the breeding objectives model positively accounts for body tissue mobilisation (through extra yield), but not the negative cost of replenishing body tissue. Two methods have been proposed: 1) Including BCS directly into BW by calculating and assigning an economic value to BCS and 2) Adjusting liveweight Breeding Values (BVs) for BCS, which would mean that liveweight BVs would be expressed at a constant BCS (indirect method). Energy equations were used to calculate the direct economic value for BCS and included a sensitivity analysis. With an economic weight of $25, the percentage emphasis of BCS in BW would be 3.4%. Including BCS in BW, either directly or indirectly, had little impact on sire rankings (rank correlations with and without BCS within breed were >0.99) and would only have a small impact on the economic response of BW ($0.02 net /cow/annum) and the improvement in BCS (0.006 BCS units/cow/annum). It is concluded that there would be little benefit to including BCS as an independent trait in BW. Body condition score is already included as a predictor in the genetic evaluation of fertility and breeding values for BCS will be estimated routinely from the fertility model.

Bovine viral diarrhoea virus in dairy cattle in New Zealand - studies on its prevalence, biologic and economic impact - Compton CWR; McDougall S; Heuer C (Proceedings of the New Zealand Society of Animal Production, 2006)
The majority (>90%) of dairy cattle will conceive following insemination or natural service, but only about 55% of cattle calve to any single mating. The majority of losses occur before the time of pregnancy recognition and such cattle are generally detected in oestrus and rebred. However, losses do occur after the period of pregnancy recognition resulting in prolonged duration of open periods and increased probability of culling for infertility. Reasons for loss include genetic abnormalities, infectious agents such as Neospora caninum, bovine viral diarrhoea virus (BVDV), and plant toxicities. The incidence, causes and economic impact of pregnancy loss are poorly defined in New Zealand. In a survey of bulk tank milk, 93% of 141 dairy herds had >10% of cows with BVDV antibody. In another study, 602 herds with a high vs. low bulk tank milk (BTM) BVDV antibody concentration were associated with 1.7% higher annual abortion rates, 2.9d longer calving to conception intervals, 0.04 more services/conception, and 1kg/d reduced solid corrected milk production. Losses due to BVDV were assessed as $90/cow/year in affected herds. It is concluded that pregnancy loss imposes significant economic costs on the New Zealand dairy industry and that BVDV is likely to be major contributing causative agent. Further research is required to evaluate the effects of BVDV on reproduction in dairy herds, the risk factors for the disease and the cost:benefit of control or eradication strategies.

Chevre meat' (goat meat) impressions and taste responses by Japanese - Ozawa T; Nishitani J; Blair HT (Proceedings of the New Zealand Society of Animal Production, 2006)
To investigate the strong prejudice against goat meat and to assist with promoting goat meat consumption in Japan, a taste-test survey and two questionnaire surveys were carried out amongst 30 university students. A pre-questionnaire survey was undertaken before the goat meat was tasted to understand the first impressions of the meat. Three different goat meat dishes (simmered meat and potatoes, goat casserole and sweet and sour goat) were served for taste evaluation. The results from this survey suggested that goat meat should be rebranded before embarking on a promotional campaign in Japan. "Chevre meat" has been chosen as a new term to promote goat meat. The phonological phrase "goat" in Japanese is not appealing to the Japanese consumer. Instead of using the Japanese word for goat, "chevre" (which in French means goat) is suitable for promotion. Combining the French and English words together as "chevre meat" sounds attractive to the Japanese consumer. Attaching an attractive recipe card to the chevre meat package will help consumers to understand how to prepare goat meat. Based on these results, a New Zealand exporter has undertaken to ship a New Zealand goat meat sample to Japan beginning in late 2005.

Clover-rich diets and production, behaviour and nutrient use by cows in late lactation - Cosgrove GP; Burke JL; Death AF; Lane GA; Fraser K; Pacheco D; Parsons AJ (Proceedings of the New Zealand Society of Animal Production, 2006)
The nutritional value of legumes for high milk production is seldom captured because grazed dairy pastures in NZ typically contain insufficient legume to satisfy the cows’ requirements. This paper reports interim results from a project investigating novel methods of forage presentation to cows, to enhance the contribution of legume to their diet. Four groups of spring-calving cows (n=5) in late-lactation were allocated to four treatments in a balanced, cross-over design. Two treatments consisted of spatial and temporal arrangements of grass and white clover allocated to cows as follows: i) continuous free access to grass and white clover growing separately as side-by-side monocultures (G/C) and ii) grass-only at `night` between the afternoon and morning milking and clover-only during the `day` between morning and afternoon milking (GnCd). These were compared against controls of iii) a typical mixed ryegrass-white clover pasture (Mix; an industry standard) and iv) a ryegrass-only pasture (Grass; a forage standard). Cows grazed each treatment for 8 days before moving to the next treatment in the pre-determined sequence. Measurements included milk production and composition, the time spent grazing during the day and the night (separately for grass and white clover in G/C) and the concentrations in the milk of skatole and indole, as metabolic indicators of nutrient acquisition and utilisation in the contrasting forage treatments. Cows offered G/C or GnCd produced 19.4 and 17.9 kg milk/cow/day, respectively, compared with 15.0 and 14.6 kg/cow/day when offered Mix or Grass, respectively (P=0.01, SEM=0.74). The diurnal distribution of grazing was influenced by pasture treatment (treatment x time interaction P <0.001). Cows on G/C grazed proportionately more at ‘night’ and cows on GnCd proportionately less at ‘night’ compared with Grass or Mix. GnCd constrained the cows to spend less time grazing clover than those offered G/C (245 vs. 408 mins grazing clover during 24 hrs) and more time grazing grass (253 vs. 105 mins in 24 hrs). The apparent `restriction` in GnCd to grazing clover-only during the day did not significantly reduce milk yield compared with G/C. The spatial and temporal allocations of grass and clover affected the concentrations of indolic compounds in PM and AM milk, suggesting there is scope to improve the efficiency of protein utilisation in the rumen.

A comparison of sites for monitoring body temperature of cattle and sheep - Smaill AL; Barrell GK (Proceedings of the New Zealand Society of Animal Production, 2006)
Four experiments were carried out to investigate whether temperature measurements recorded continuously from the vagina of ruminant animals are comparable to those measured at the rectum. Normal vaginal, rectal and ruminal temperatures of sheep (n = 4) and cattle (n = 2) were measured twice for 4 h and 2.5 h, respectively. Fever was induced by administration of endotoxin to sheep (0.8 µg/kg live weight, n = 4) and cattle (0.2 µg/kg live weight, n = 2) and the temperatures were recorded for 4 h. Normal vaginal and rectal temperatures were recorded simultaneously in 8 sheep for 2 h and separately in 6 and 12 sheep, respectively, for 4 h. In sheep, mean (± SEM) rectal temperature ranged between 39.1 °C and 39.4 °C (± up to 0.11 °C) and mean vaginal temperature ranged between 39.2 °C and 39.5 °C (± up to 0.17 °C). In cattle, means (± SEM) of rectal and vaginal temperatures were both 38.6 ± 0.10 °C. Endotoxin elevated temperatures by about 2 °C and ruminal temperature was occasionally up to 1 °C higher than rectal or vaginal temperature. Rectal and vaginal temperatures did not differ significantly from each other in either species. The findings indicate that, for monitoring the internal thermal environment of cattle and sheep, vaginal temperature is equivalent to rectal temperature and support other evidence that temperature of the rumen can be independent of body temperature.

Concluding Remarks : Genomics and the future of wool production - Nixon AJ (Proceedings of the New Zealand Society of Animal Production, 2006)
Oil supplements can be used in dairy rations to increase dietary energy density (and energy intake) and reduce methane (CH4) emissions from rumen fermentation. Trials at Dexcel measured effects of oil supplementation on dry matter intake (DMI), milk yield and methane production after lactating dairy cows were fed pasture-based diets for short (14-day) and long (12-week) periods. In the short-term trial, 32 cows received either no oil or three mixtures of sunflower and fish oil at 500g/d. In the long-term trial 20 cows grazed pasture and received either no oil or 300g linseed and fish oil for 11 weeks prior to methane measurements. The type of oil in the short-term trial did not affect methane production and oils had no effect on DMI or milk yield but reduced total methane emissions by 27% (176 vs. 242g CH4/cow/d, sed=10.6) and CH4/kg DM (13.5 vs. 18.5g CH4/kg DM, sed=0.88). In the long-term trial, oil had no effect on methane emissions (353 (oil) vs. 323g CH4/cow/d (control), sed=17.0 and 21.7 vs. 23.0g CH4/kg DM, sed=1.01). These trials did not show benefits of oils for milk production and emphasize the need for longterm studies when developing on-farm strategies for methane mitigation.

Contract Introduction : The problem of anthelmintic resistance - Hoskin SO (Proceedings of the New Zealand Society of Animal Production, 2006)
S³ was initiated in November 2004 by a small number of industry individuals and a group of elite merino and mid micron breeders and will run until November 2007. It is a project that brings together two sectors of the sheep breeding industry that views the sustainable management of parasites critical to their and their commercial client’s futures. The project aims to examine the issue of sustainable parasite management via a number of approaches and not to focus on a single element of parasite management. Key elements addressed include the synergy between sustainable parasite management, breeding for resistance and property bio-security, to enhance farming operations.

Development of a model to predict pasture intake for grazing dairy cows in Argentina - Baudracco J; Lopez-Villalobos N; Holmes CW; Brookes IM; Kemp P; Comeron E; Romero LA; Horan B; Dillon P; Berry D (Proceedings of the New Zealand Society of Animal Production, 2006)
The nutritional value of legumes for high milk production is seldom captured because grazed dairy pastures in NZ typically contain insufficient legume tosatisfy the cows’ requirements. This paper reports interim results from a project investigating novel methods of forage presentation to cows, to enhance the contribution of legume to their diet. Four groups ofspring-calving cows (n=5) in late-lactation were allocated to four treatments in a balanced, cross-over design. Two treatments consisted of spatial and temporal arrangements of grass and white clover allocatedto cows as follows: i) continuous free access to grass and white clover growing separately as side-by-sidemonocultures (G/C) and ii) grass-only at 'night' between the afternoon and morning milking and clover-only during the 'day' between morning and afternoon milking (GnCd). These were compared against controlsof iii) a typical mixed ryegrass-white clover pasture (Mix; an industry standard) and iv) a ryegrass-only pasture (Grass; a forage standard). Cows grazed each treatment for 8 days before moving to the next treatment in the pre-determined sequence. Measurements included milk production and composition, the time spent grazing during the day and the night (separately for grass and white clover in G/C) and the concentrations in the milk of skatole and indole, as metabolic indicators of nutrient acquisition and utilisation in the contrasting forage treatments. Cows offered G/C or GnCd produced 19.4 and 17.9 kg milk/cow/day, respectively, compared with 15.0 and 14.6 kg/cow/day when offered Mix or Grass, respectively (P=0.01, SEM=0.74). The diurnal distribution of grazing was influenced by pasture treatment (treatment x time interaction P <0.001). Cows on G/C grazed proportionately more at ‘night’ and cows on GnCd proportionately less at ‘night’ compared with Grass or Mix. GnCd constrained the cows to spend less time grazing clover than those offered G/C (245 vs. 408 mins grazing clover during 24 hrs) and more time grazing grass (253 vs. 105 mins in 24 hrs). The apparent 'restriction' in GnCd to grazing clover-only during the day did not significantly reduce milk yield compared with G/C. The spatial and temporal allocations of grass and clover affected the concentrations of indolic compounds in PM and AM milk, suggesting there is scope to improve the efficiency of protein utilisation in the rumen.

Development of a 'Wapiti Score' visual assessment tool for determining introgression of Wapiti genes in young red deer - Ward JF; Scott IC; Asher GW; Littlejohn RP (Proceedings of the New Zealand Society of Animal Production, 2006)
Red deer are the predominant farmed breed type in New Zealand, but crossbreeding red females with wapiti (or elk) males in a terminal sire system is common. Introgression of wapiti genes into the national red deer breeding hind herd has been shown to have a negative impact on the pregnancy rate of 16-18 month old hinds. We devised a four point visual scoring system (‘Wapiti Score’), based on wapiti phenotype characteristics, for application to weaner (6-10 month old) red deer, to allow rapid detection of wapiti introgression. This scoring system was trialled and refined using 449 rising-one-year-old red deer of mixed genotype and sex on a commercial breeding and finishing farm, during three pelage phases. For a subset of 186 animals ‘Wapiti Score’ was compared to the DNA based GenomnzTM GenometerTM G3 Hybrid Test ‘Estimated Elk’ (EstElk), where EstElk; is the estimated proportion of wapiti (elk) genes in an individual animal predicted by the GenometerTM. A significant positive correlation (P < 0.05) was found between EstElk and ‘Wapiti Score’ for two independent observers, with an increase of one point in ‘Wapiti Score’ corresponding to an increase of approximately 0.10 in EstElk. The strongest correlation between Wapiti Score and EstElk were from the winter and spring scores. The effectiveness of Wapiti Score as a tool for classifying young deer by breed-type (red deer or wapiti ) was assessed using 0.2 EstElk as the breed-type threshold and comparing that against different selection Wapiti Scores (1-3).

Development of new fertility breeding values in the dairy industry - Harris BL; Pryce JE; Xu ZZ; Montgomerie WA (Proceedings of the New Zealand Society of Animal Production, 2006)
This paper provides the basis for a new method for calculating fertility breeding values. The objective of this study was to: firstly, investigate the data extract of mating and calving records from Livestock Improvement`s national database to identify improvements, secondly investigate the definition of the fertility trait from percent of calves born from artificial insemination (AI) to 42 day calving rate, and thirdly explore the inclusion of milk production and body condition score information. The overall aim was to improve the accuracy of the fertility breeding values available when a sire`s daughters have completed their first lactation (i.e., the time of the sire`s first proof). A new procedure for routine national evaluation of these traits is outlined. Results from the new system are given. Possible future enhancements to the new system are discussed. The new method improves the accuracy of the fertility breeding value for first crop sires with 80 daughters from 45% to 52%. The inclusion of body condition score and milk production in the calculation of the fertility breeding value improves the response to selection for fertility within breeding worth index by 34% per annum. The improvement in response to selection is worth 0.18 $/cow/year or approximately $700,000 annually to the dairy industry.

Diet or strain: Effects on postpartum anovulatory interval in dairy cows - Chagas LM; Gore PJS; Sheahan AJ; Lee JM; Watkins KA; Aspin PW; Roche JR (Proceedings of the New Zealand Society of Animal Production, 2006)
Changes in cow genetics and systems of farming have had large effects on the reproductive performance of dairy cows. The objective of this study was to determine if grain supplementation modified the previously identified effects of Holstein-Friesian (HF) strain on the postpartum anoestrus interval (PPAI). Thirty multiparous Overseas (OS) HF and 30 New Zealand-HF cows from a 1990s strain (NZ) were offered unrestricted access to fresh pasture and randomly allocated to three levels of a maize and barley-based concentrate supplementation (0, 3 or 6 kg DM/day). Postpartum anovulatory interval (PPAI) was not significantly affected by either strain or diet, and there was no significant strain x diet interaction. Results suggest that the nutritional requirements necessary for multiparous NZ or OS HF cows to resume oestrous cycles before 40 days postpartum can be achieved when offered unrestricted access to high quality pasture. In this circumstance, additional concentrate feeding did not alter the length of the postpartum anoestrous interval.

Do ewes with twin and triplet lambs produce different yields of milk and does the grazing behaviour of their lambs differ? - Peterson SW; Kenyon PR; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2006)
This trial was designed to determine if ewes with triplets produce more milk than those with twins, and, if not, do triplet lambs compensate by extra grazing. Milk yield (MY) of ewes with twin (n=13) and triplet (n=8) lambs, grazing pasture in spring was measured four, seven and ten weeks postpartum. Ewes and lambs were separated in the morning and MY was measured by the oxytocin method. MY did not differ in ewes with triplets (2525 ± 243 g/d) from that in ewes with twins (2204 ± 149 g/d) at week four, week seven (1847 ± 238 versus 1684 ± 111 g/d), or at week ten (1448 ± 139 versus 1264 ± 85 g/d). NIRS analyses showed no significant consistent difference in fat (triplet: twin 7.7: 7.5 ± 0.4%), protein (4.4: 4.3 ± 0.2%), lactose (4.71: 4.72 ± 0.03%) and total solids (17.48: 17.36 ± 0.35%) composition of milk from ewes with triplet or twin lambs (data are means of all samples). Mammary gland dimension B, the distance across the gland next to the teats, was better correlated (R2 0.31, P<0.05) with MY than other dimensions tested. Behaviour observations (whether the lamb was grazing or suckling) were made weekly 3-9 weeks postpartum. The time spent grazing by triplets (39.4 ± 1.94 % on lactation day 29) was significantly greater (P<0.05) than the time spent grazing by twins (37.7 ± 1.94% on lactation day 29) on three observation days and, overall, triplet lambs spent more time grazing than twin lambs. Birth weight of twin lambs (4.39 ± 0.14 kg) was not significantly greater than that of triplets (4.00 ± 0.20 kg), but they grew significantly faster (P<0.05) from week four till week ten, gaining 17.0 kg compared to 14.9 kg for triplets. Triplets suffer a relative lack of available milk nutrients compared to twins and are not able to completely compensate for this by increasing grazing time.

Eating quality of commercial meat cuts from Australian lambs and sheep - Pethick DW; Pleasants AB; Gee AM; Hopkins DL; Ross IR (Proceedings of the New Zealand Society of Animal Production, 2006)
Triplets occur when lambing percentages exceed 130%. When triplets are left with their dam, survival is often less than 75%. Artificial rearing of onelamb from each set of triplets offers the chance to increase survival rates. But experience to date has frequently resulted in death rates of10% to 30% of lambs. On the author’s farm about 100 sets of triplets are born each year. In 2002 an artificial rearing system was put in place based on the Poukawa system. The smallesttriplet from each set was removed for artificial rearing. In 2002 and 2003, when lambs were 3 to 5 weeks old, up to 25% died. A worldwide information search suggested that the disorder was possibly abomasal bloat. A Norwegian method of preparing “soured” milk replacer that had been demonstrated to limit abomasal bloat was adapted for New Zealand conditions. Lambs are fed cow colostrum for two days, followed by ad lib. cold “soured” whole milk replacer and ad lib. meal. In 2004 and 2005, there have been no deaths due to abomasal bloat. Total deaths from 199 lambs have been 9. Live weight gains of the lambs have been 220-250 grams per day till 8 weeks.

Economic consequences for sheep farmers from using genetic technologies - Sumner RMW; Davison RM (Proceedings of the New Zealand Society of Animal Production, 2006)
Agricultural commodity products experience marked price trends over time. In the 1980s the balance between returns to growers, before deducting costs, from meat and wool was 46/54. The ratio has now shifted to 83/17. Price increases of the magnitude currently required to redress this imbalance for wool growers may be achievable through genomic technologies. Such technologies could create a demand for biological components extractable from a proportion of the national clip, permit the development of novel fibre types and significantly reduce wool harvesting and husbandry costs. The economic benefits to sheep owners through changing wool characteristics such as fibre diameter or crimp are limited by existing high volume, low profit margin value chains. New technologies which improve wool characteristics and value should be complemented where possible by direct supply relationships between producers and end-users in order to justify their development and to sustain price premiums.

An economic evaluation of automatic milking systems for New Zealand dairy farms - Jago JG; Davis KL; Newman M; Woolford MW (Proceedings of the New Zealand Society of Animal Production, 2006)
An economic analysis for automatic milking for a medium sized farm set up to milk 450 cows and installing either a 40-bail rotary dairy with automated cup removal and drafting or a 5-unit Greenfield system is evaluated. The analysis used a model that incorporated findings from the previous 5 years of research and development at the Greenfield automatic milking project and used physical and financial data collected in Dexcel’s 2003/04 Economic Farm Survey for the conventional milking system comparison. The model assumed a payout of $4.25/kg milk solids (MS) and used current cost of technology. Once cows were established into the Greenfield System, the cost of producing 1 kg MS was 27% higher than for the conventional rotary system. This was due to higher interest, depreciation and service contract costs, despite the lower labour, cow health and dairy costs. Sensitivity analysis showed that when other factors were held constant a 70% decrease in capital cost or a more than two-fold increase in cow throughput was required for the Greenfield System to be as economic as the rotary system. Alternatively combining future improvements in AMS technology and farm system development including improved throughput to 112 cows/AMS, a 25% decrease in milk harvesting system capital cost, equivalent production and a 10% increase in the cost of labour produce a similar economic performance for the two systems.

Effect of an extended milking interval on recovery of milk yield and somatic cell count in dairy cows - Dalley DE; Davis SR (Proceedings of the New Zealand Society of Animal Production, 2006)
The objective of the study was to determine whether lactation could be re-initiated after several days without milking. Thirty-six cows in mid lactation were subjected to a single period without milking of either 2, 4 or 7 days. Following these periods twice daily milking resumed. Two days after resumption of twice daily milking, milk yield was depressed to 92, 80 and 51% of pre-treatment (twice a day milking) rates in the 2, 4 and 7-day treatments. The 2- and 4-d treatments achieved pre-treatment milk yields 3 and 4 days after the resumption of milking, respectively. The 7-d treatment failed to achieve pre-treatment yields in this time period. However, 6 days after the resumption of twice-daily milking there was no difference in average milk yield between the 3 groups. Following the resumption of milking, SCC exceeded 2 million cells/ml for the first day in all treatments. Within 3 days the SCC for the 2 and 4-day treatments were below the 400, 000 cells/ml penalty threshold. However, it took five days milking to achieve this level for the 7-day treatment. The results indicate that successful lactations can be re-established after up to 7 days without milking in mid-lactation, with minimal carry-over effects on milk yield for the rest of the lactation.

The effect of colostrum intake on mortality and growth of Friesian bulls from birth to slaughter - Muir PD; Thomson BC; Fugle CJ (Proceedings of the New Zealand Society of Animal Production, 2006)
Dairy cow glucose requirements increase dramatically during the weeks preceding calving, suggesting that supplements that increase glucose supply (rapidly fermentable carbohydrates) would reduce precalving mobilisation of body tissue and improve subsequent milk production. Sixty-eight multiparous dairy cows were randomly allocated to one of two diets for 36 ± 8.7 days precalving. All cows were fed pasture and pasture-silage precalving, with one group also receiving 3kg DM of a barley-maize concentrate. Precalving diets were iso-energetic (114 MJ/cow/day).At calving, cows within each precalving feeding treatments were randomly allocated to two dietary treatments for 35 days in a 2x2 factorial arrangement. Postcalving, all cows received pasture and pasture silage with one group also receiving 5.0 kg DM of a barley-maize concentrate. Postcalving diets were alsoiso-energetic (179 MJ/cow/day). Milk yield and composition, and liveweight (LW) and body condition score (BCS) were assessed weekly for five weeks. Blood was sampled on day -21, -14, -7, 0, 1, 2, 3, 4, 7, 14, 21, 28 and 35 relative to calving, and plasma samples were analysed for indicators of energy status. Average milksolids yield (1.9 kg/cow/d) during the five weeks postcalving was not affected by either pre- or postcalving concentrate supplementation, although protein to fat ratio was higher in supplemented cows. Similarly, concentrate supplementation pre- or postcalving did not affect either LW or BCS change before or after calving. Cows receiving concentrates precalving had higher (P<0.001) plasma non-esterified fatty acid (NEFA) concentrations, but otherwise were not different to those receiving an equivalent energy intake from pasture and pasture silage. Postcalving concentrate supplementation increased (P<0.01) plasma glucose and NEFA and decreased (P<0.001) plasma B-OH butyrate. Results suggests little effect on milkproduction by replacing energy from structural carbohydrates in high quality pasture with energy from non-structural carbohydrate during the transition period.

Effect of cow genotype and feed allowance on milk composition - Turner S-A; MacDonald KA; Back PJ; Thomson NA (Proceedings of the New Zealand Society of Animal Production, 2006)
The effect of strain of Holstein-Friesian and level of feed allowance on milk composition, individual milk proteins, and minerals was examined in a seasonal calving pastoral dairying system. The trial included two high genetic merit strains of either North American (OS90) or NZ (NZ90) genetics, and one strain representing NZ 1970’s genetics (NZ70). Each strain was farmed under systems designed to provide total feed allowances of 4.5 to 7.0 t DM/cow/year. Milk composition was affected by strain of cow and by feed allowance. Strain of cow influenced crude protein (P<0.05), true protein (P<0.01) and casein (P<0.01) concentrations, with the NZ90 and OS90 strains having higher concentrations than the NZ70 strain. Increased feed allowance resulted in increased crude protein (P<0.05), true protein (P<0.05) and casein (P<0.05) concentrations. Strain, but not increased feed allowance affected the protein:fat ratio, with the OS90 strain having a higher ratio (P<0.05) than the NZ strains. Strain altered concentrations of á-casein (P<0.05), with NZ90 having the highest concentrations and NZ70 the lowest concentrations. No consistent effect of strain or feed allowance was determined on whey proteins except for â-lactoglobulin (P<0.027), where the OS90 strain had higher concentrations than the NZ strains. No consistent effect of strain or increasing feed allowance was seen on milk mineral concentrations. These results demonstrate that different selection and breeding policies have influenced major milk components which may influence milk processing and product characteristics.

Effect of dairy cow breed on the metabolic adaptation to lactation - Back PJ; Meier S; Barnett CME; Cursons RT; Thomson NA (Proceedings of the New Zealand Society of Animal Production, 2006)
Three breeds (20 Friesian, 20 Jersey and 20 Jersey/Friesian crossbred multiparous cows) were used to determine the effect of breed on indicators of metabolic status and the post partum anovulatory interval (PPAI). Effect of breed on circulating concentrations of metabolites and hormones, liver mRNA levels and PPAI was established. Weekly blood samples were taken for the first 6 weeks of lactation. Liver biopsy samples were taken from a sub-sample of cows of each breed between 23-33 days post partum, to determine levels of expression of T-GHR, GHR-1A and IGF-1 receptors using RT-PCR. Milk progesterone analysis was used to determine PPAI. There was a significant breed effect on circulating concentrations of â-hydroxy butyrate (P<0.01), non-esterfied fatty acids (P<0.001), triacylglycerols (P<0.001) and leptin (P<0.01), with Jersey cows having higher concentrations of these hormones and metabolites than Friesian or crossbred cows. Despite the concentration differences between breeds, only leptin showed a significant difference (P<0.01) in the rate of change in concentration across time between the breeds. Jersey cows were observed to have shorter PPAI (34 vs 42 and 44 days for Friesian and crossbred cows respectively: SED 6 days) but this was not statistically significant (P=0.18). There was no difference in the expression of mRNA levels of TGHR, GHR-1A and IGF-1 receptors in the liver. It appears that grazing Jersey cows have a different fat metabolism, which affects the regulation of circulating leptin concentrations and this may have contributed to their apparent ability to return to cyclicity earlier.

Effect of genotype and diet on milksolids production, body condition, and reproduction of cows milked continuously for 600 days - Kolver ES; Roche JR; Burke CR; Aspin PW (Proceedings of the New Zealand Society of Animal Production, 2006)
Milking cows for two consecutive years, with calving and mating occurring every second year, may exploit the superior lactation persistency of high yielding cows while improving reproductive performance. This study tested the feasibility of extended lactations in pastoral systems using divergent dairy cow genotypes (New Zealand [NZ] or Overseas [OS] Holstein-Friesian [HF]) and levels of nutrition (0, 3, or 6 kg concentrate DM/cow/day). Cows calved on 28 July 2003 and remaining cows were dried off by 6 May 2005. Of the 56 cows enrolled, 93% were milking at 500 days in milk (DIM) and 18% were milking at 650 DIM. Dietary treatments did not affect DIM (605 ± 8.3; Mean ± SEM), but there was a trend (P=0.09) for OS HF to have longer lactations than NZ HF. Genotype x diet interactions were detected for the total yield of milk and milksolids per cow, and as a percentage of liveweight. Differences between genotypes were greatest at the highest level of supplementation. Compared to NZ HF, OS HF produced 35% more milk, 24% more milk fat, 25% more milk protein, and at drying off had 1.9 units less body condition. Annualised milksolids production from NZ HF was 79% of a normal season’s production, compared to OS HF that produced 94%. Compared to NZ cows, OS cows had a similar 21-day submission rate (85%), a lower 42-day pregnancy rate (56% vs. 79%), and a higher final empty rate (30 vs. 3%) when mated at 451 days after calving. These results indicate that productive extended lactations up to 650 days are biologically possible on a range of pasture diets, and with appropriate cow genetics and feed management may ameliorate poor reproductive performance in high yielding dairy cows without sacrificing milksolids production.

The effect of maternal nutrition during gestation on the reproductive success of female progeny as 2-tooths - Corner RA; Kenyon PR; Stafford KJ; West DM; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2006)
The inter-generational effect of birth rank and nutrition during pregnancy was assessed by examining the reproductive success of female progeny at their first mating at 2 years of age. Fifty-six ewes born as a twin or triplet and whose dam was maintained on 2 or 6 cm sward height from mid-pregnancy to parturition were synchronised and bred to Romney rams. Pregnancy diagnosis was conducted using ultrasound on day 71 from the start of mating (P71). All ewes were maintained as one mob under commercial farming conditions throughout pregnancy. Within 12 hours of birth lambs were ear tagged, weighed and body dimensions (CRL, girth, forelimb and hind limb lengths) were recorded. Lamb live weights were also recorded at day 48 after the mid-point of lambing (L48). Fifty-one ewes lambed of the 56 ewes that were bred. Twin-born ewes had significantly longer gestation lengths (by 1.3 days) than triplet-born ewes. Singleton lambs born to triplet-born ewes were significantly (P<0.05) lighter (4.6 kg) at birth than singleton lambs born to twin-born ewes (5.1 kg). Singleton lambs whose grand-dams were maintained on 2cm pastures during pregnancy and whose dam was born as a twin had significantly (P<0.05) longer hind limbs than their counterparts whose grand dam was maintained on 6 cm and whose dam was born a triplet but they did not differ in birth weight. Dam birth rank and the nutritional treatment of their grand-dam had no significant effect on twin-lamb live weight and body dimensions at birth. These results suggest that selecting triplet ewe lambs for breeding could have detrimental effects on flock productivity. In addition a previous study involving the same animals reported triplet born ewes displayed poorer maternal behaviour. To the authors knowledge this is the first finding of this kind and could have implications for ewe selection on New Zealand farms.

The effect of nutrition during pregnancy on the behaviour of adolescent ewes and their lamb(s) within 12 hrs of birth - Corner RA; Kenyon PR; Stafford KJ; West DM; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2006)
Hogget mating has become more common in recent times as a management strategy to produce additional lambs. The productivity of hogget mating is limited by low lamb birth weights and poor lamb survival. A study has shown that maternal nutrition during pregnancy in hoggets had no effect on the birth weight or survival of lambs. This study investigated the effect of nutrition during pregnancy on the post-parturient behaviour of hogget ewes and their lambs. On day 13 after the mid-point of breeding hogget ewes were stratified by breed and live weight and randomly allocated to one of three feeding regimes: Low (gained 10kg of live weight by parturition), Medium (20kg) and High (30kg). Within 12 hours of birth lambs were ear tagged and the maternal behaviour of hogget ewes was recorded using a maternal behaviour score (MBS) a five point measure of a ewe’s response to the handling of her lambs. Behavioural observations of the hogget and her lamb(s) were made for 5 minutes after the completion of tagging the lamb. Singleton-bearing hogget ewes fed on the high plane of nutrition had significantly (P<0.05) greater maternal behaviour scores than singleton-bearing hoggets fed on low or medium planes. In the low fed group, significantly (P<0.05) fewer hoggets bleated in response to their lamb (60%) compared with medium (73%) and high (85%) fed hoggets. Of the lambs that bleated, those born to hoggets in the medium fed group bleated significantly (P<0.05) more than lambs born to hoggets in the low or high fed groups. Feeding hogget ewes on a high level of nutrition had a positive impact on hogget and lamb behaviour within 12 hours of birth. A high level of nutrition during pregnancy may result in behaviours that increase survival of lambs born to hogget ewes.

Effect of Se-amended fertilisers on the Se status of grazing dairy cattle - Grace ND; West DM (Proceedings of the New Zealand Society of Animal Production, 2006)
Selenium (Se) is an important trace element for dairy cattle and deficiencies (0.03 mg Se/kg DM) are associated with lowered milk yields and impaired fertility in grazing cows. As many dairy farms have a comprehensive fertiliser programme the use of Se-amended fertilisers (prills) could be an effective approach to prevent Se deficiency. Three farmlets (6-7 ha) were established and grazed with 13 cows/farmlet balanced for age, calving date and production. The treatments were 1) untreated control, 2) Sel Se prill (Selecote Ultra), and 3) Rav Se prill (Ravensdown Selprill Double). The prills were mixed with 15% potassic superphosphate and applied at 250 kg/ha, in early October, to provide 10 g Se/ha. This is Day 1 of the study. The cows were allocated to treatments 4 weeks later and changes in pasture Se, blood Se, serum Se, milk Se concentrations and blood glutathione peroxidase activity were monitored over the next 12 months. Untreated pasture Se concentrations ranged from 0.03 to 0.04 mg/kg DM, while pastures treated with prills had pasture Se concentrations > 0.5 mg/kg DM within 14 days after treatment, before decreasing to 0.06 mg/kg DM after 121 days, after which they ranged between 0.06 and 0.26 mg Se/kg DM for the Sel prill, and between 0.06 and 0.03 mg/kg DM for the Rav Se prill over the next 251 days. The mean (± SE) blood Se of cows grazing the control pasture was 280 ± 30 nmol/L, while in cows grazing pasture treated with the Sel Se prill blood Se concentrations increased to 1364 ± 112 nmol/L after 372 days. In the case of cows grazing pasture treated with Rav Se prill, blood Se concentrations increased to 1192 ± 66 nmol/L within 60 days, before decreasing slowly to 740 ± 65 nmol/L at 372 days. Blood glutathione peroxidase activity followed a similar pattern to the blood Se. The mean serum Se concentrations of the untreated cows was 151 nmol/L, while in animals on the Sel Se prill-treated pasture they reached a small peak at Day 64, followed by a decrease and then continued to increase to 675 nmol/L at Day 372. In contrast, for cows on the Rav Se prill treatment the serum Se concentrations reached a peak of 920 nmol/L at Day 64, and then decreased to 263 nmol/L at Day 372. Milk Se followed a similar pattern to serum Se. Selenium-amended fertilisers were found to be effective in raising the pasture Se concentrations for 4 or 12 months, depending on Se prill composition, which then in turn increased blood Se concentrations of dairy cows for at least 12 months.

Effect on fleece weight of combining genes from four flocks independently selected for increased fleece weight - Sumner RMW; Clarke JN; Blair HT; Cullen NG; Henderson HV (Proceedings of the New Zealand Society of Animal Production, 2006)
This study investigated whether heterosis was present when crossing sheep from four closed Romney flocks selected for increased fleece weight. Three of the flocks had been developed by AgResearch (C, W and H) and one by Massey University (M). Each ewe was joined with a single ram according to a diallel design to generate single-line, two-line and four-line cross progeny. The trial ran from 1988 to 1996 with 599 records available for analysis. In rank order, the mean (± standard error of mean) greasy yearling fleece weight (kg), adjusted for year, sex, pre-shearing live weight and days of wool growth was W (3.41 ± 0.08), H (3.39 ± 0.12), C (3.31 ± 0.10), M (3.10 ± 0.15) for the "single-line" groups, WC (3.40 ± 0.09), MW (3.36 ± 0.10), CH (3.24 ± 0.08), WH (3.16 ± 0.11), MH (3.14 ± 0.11), MC (3.14 ± 0.10) for the "two-line" crosses and 3.26 ± 0.06 for the four-line cross. Combining sheep from two or more flocks independently selected for increased fleece weight resulted, on average, in no heterosis in wool production among resultant progeny.

Effects of artificial insemination on the incidence of long return intervals - Pino CS; Macmillan KL; Anderson GA (Proceedings of the New Zealand Society of Animal Production, 2006)
The Phantom Cow Syndrome is a major impediment to achieving compact conception patterns in Victorian herds. Some inseminated cows fail to return for a further insemination even though they are not pregnant because the corpus luteum formed following insemination is maintained for an extended period. Five years of records were obtained from a herd of Holstein cows in Northern Victoria. Each cow was fitted with a hock tag that combined electronic identification with pedometer monitoring for oestrus. It was the only detection method used within a herd of up to 550 cows that had three AB programs of 6 to 8 weeks in each year. There were periods when cows detected in oestrus would be inseminated and others when they would not. Records were available for 2777 inseminations. The return intervals following these inseminations were classified as: Short (<18 days); Normal (18 to 24 days); or Long (>24 days). The overall conception rate for the 2777 inseminations made from 41 days to 160 days post-calving was 41.7%. The 417 Long intervals represented 15% of all inseminations and 25.8% of cows not confirmed pregnant to a preceding insemination. Only 54 of 1459 oestrus events (3.7%) not associated with an insemination were followed by a Long cycle (P<0.001). The proportion of Long returns declined linearly from 19.9% among the 738 cows inseminated from 41 to 60 days post-calving to 7.4% among the 189 cows inseminated from 141 to 160 days post-calving. These results demonstrated that the percentage of Long return intervals increased significantly following insemination. The magnitude of this increase declined with an increase in the interval from calving to insemination.

Effects of conjugated linoleic acid on bioenergetics and milk production parameters in grazing dairy cows offered ad libitum or restricted pasture - Kay JK; Mackle TR; Bauman DE; Thomson NA; Baumgard LH (Proceedings of the New Zealand Society of Animal Production, 2006)
Conjugated linoleic acids (CLA) reduce milk fat synthesis in grazing dairy cows and often improve net energy balance (EBAL). Study objectives were to determine if CLA-induced milk fat depression (MFD) could be utilised during times of feed shortage (i.e drought) to improve bioenergetic and milk production parameters. Twelve multiparous mid-lactation rumen-fistulated Holstein cows were offered ad libitum (AL) or restricted (R) pasture and abomasally infused twice daily with 0 (0) or 50 (50) g/d CLA in a cross over design. Treatment periods lasted 10 d and were separated by a 10-d washout period. Milk and plasma samples were averaged from d 9 and 10, and EBAL was calculated from d 6-10, of the infusion periods. Pasture restriction reduced (P<0.05) the yield of milk and milk components. CLA reduced (P<0.01) milk fat yield by 45 and 46 % in AL and R, respectively. There was no effect of CLA on milk yield nor milk lactose content or yield, however milk protein content increased (P<0.05) in both AL and R, resulting in an increased (P<0.05) protein yield of 6 and 9% respectively. The CLA-induced changes to milk fat and protein increased (P<0.01) protein:fat ratio by approximately 2-fold in both AL and R. Calculated EBAL improved following CLA infusion (-1.84 vs. 11.22 and 1.59 vs. 13.77 MJ/cow/d for AL and R respectively; P<0.05), however CLA did not alter plasma bioenergetic markers (including insulin, non-esterified fatty acids, â-hydroxybutyrate, urea and glucose). Data indicate that during short periods of nutrient restriction, CLA may provide an alternative management tool to improve milk protein:fat ratio and calculated EBAL, however further studies are required to determine if CLA is effective at improving bioenergetic parameters during more severe nutrient restriction.

Effects of facial eczema on indole flavour compounds in dairy cows - Fraser K; Lane GA; Morris CA; Cullen NG (Proceedings of the New Zealand Society of Animal Production, 2006)
The flavour compounds indole and skatole (3-methylindole) are characteristic of products of pasture based production systems. The formation of these indoles by metabolism of the amino acid tryptophan in the rumen is favoured by high levels of readily-digestible protein in forage diets. However liver function is also a very important factor as indoles taken up into the animal are cleared by metabolism in the liver. An investigation of a persistent flavour taint from a dairy farm suggested a link between high milk indoles and facial eczema. As part of a genetic study, 1223 dairy cows in 4 herds in the Waikato and Bay of Plenty were screened for liver damage associated with facial eczema by measuring levels of the enzyme gamma-glutamyl transferase (GGT) in the blood. We examined levels of skatole in plasma from cows selected for high GGT (> 400 i.u. l-1, 47 cows) or low GGT (< 100 i.u. l-1, 43 cows) sampled from these herds. Blood indole and skatole levels overall were higher for the ‘high GGT’ cows compared to the `low GGT` cows (P < 0.001, Mann-Whitney test). The levels of indoles in milk collected from the same cows 4 days after blood sampling on one farm showed a highly significant (P < 0.001) non-linear relationship between levels in milk and blood, with milk fat skatole reaching extremely high levels (> 2000 ng g-1) in animals with very high blood skatole (> 20 ng ml-1). As the presence of relatively few animals with such extremely high levels of indole flavour compounds in milk is likely to raise the herd mean concentration to unacceptable levels, these findings suggest that facial eczema may have significant adverse effects on milk quality as well as on production.

Environmental and physiological mechanisms underlying wool growth rhythms in New Zealand coarse wool sheep - Kendall PE; Sumner RMW; Pearson AJ (Proceedings of the New Zealand Society of Animal Production, 2006)
Coarse-woolled sheep breeds such as the Romney exhibit a pronounced annual cycle of wool growth with concomitant changes in fibre length growth rate and mean fibre diameter with maxima in summer and minima in winter. This cycle, which is entrained by seasonal changes in daylength via changes in circulating prolactin, parallels wool growth rate in Romney sheep. The cycle is also influenced by complex interactions between nutrient supply and hormones associated with reproductive status. A marked depression in wool production occurs during early pregnancy, which cannot be completely ameliorated by supplementary feeding, and does not directly involve prolactin. Additionally, in ewes, experimental and pharmacological increases and decreases in the prolactin concentration at parturition and during lactation are associated with increases and decreases, respectively, in spring and summer wool growth rate. A greater appreciation of the different mechanisms that temporally influence the wool growth cycle represents a potential means to change fleece characteristics. The development of sheep genotypes with a reduced amplitude of their wool growth cycle would significantly contribute to a reduction in fibre variability that can affect processing performance.

An evaluation of sheep meat genetics in New Zealand: The central progeny test (CPT) - McLean NJ; Jopson NB; Campbell AW; Knowler K; Behrent M; Cruickshank G; Logan CM; Muir PD; Wilson T; McEwan JC (Proceedings of the New Zealand Society of Animal Production, 2006)
The New Zealand Central Progeny Test (CPT) was first established in 2001 with the aims of improving the carcass dollar value of sires and establishing genetic links among sire referencing schemes. Over the past three seasons, a total of 72 sires from both terminal and dual purpose breeds have been evaluated for meat genetics at the AgResearch Woodlands farm and the Lincoln University Ashley Dene farm. All progeny, except the 2004 born ewe progeny from the dual purpose sires, were slaughtered at monthly intervals from December to March each year through two Alliance plants, at threshold liveweights of 34kg. Carcass measurements included cut yield (measured by ViaScan grading) eye muscle area, GR, meat pH, meat and fat colour and days to reach an 18kg carcass weight. These measurements were used to calculate three key indices; days to kill, meat value and a combined meat and growth index, as well as individual breeding values. Results showed significant variation among sires for all key traits and that no single ram or breed dominated the top of the indices or breeding values. The range of economic value was approximately $10 across the terminal and dual purpose sires evaluated, demonstrating that considerable potential exists to identify and select better terminal sires. The CPT is now commencing maternal evaluation, using the retained ewe lambs produced from the dual purpose sires.

Face facts : drenching with anthelmintics for worm control selects for drug resistance - and no excuses! - Van Wyk JA (Proceedings of the New Zealand Society of Animal Production, 2006)
Worm anthelmintic resistance is entering the final phase, where nothing remains with which to control worms at a level commensurate with profitable animal production. In Brazil, for instance, moxidectin alone or in combination with other compound(s) has failed in numerous cases in sheep and goats, and in New Zealand combined treatment of goats with moxidectin plus a benzimidazole and levamisole failed completely against Trichostrongylus and Ostertagia spp. Cattle follow closely behind, with a recent survey in Argentina indicating a prevalence of 55 % of worm populations resistant to ivermectin. It is suggested that the solution for sustainable Integrated Parasite Management is use of systems of Targeted Selective Treatment (TST) to optimise application of the phenomenon of refugia for reduced worm selection. However, due to reticence of farmers and their advisors, the required major paradigm shift will be very difficult to achieve. To overcome this, it is suggested that dedicated software be developed for specific decision support at farm level, as detailed as the intervals between TST evaluations of a given flock/herd of animals and percentages of animals to examine and treat. The conclusion reached is to face the fact that no excuse regarding animal production or farmer reticence will expunge the reality that conventional worm control is leading to intractable resistance; optimum, not maximum production is the prerequisite.

Further studies on the role of suckling in the parasite status of very young lambs infected with Teladorsagia circumcincta - Iposu SO; Greer AW; McAnulty RW; Stankiewicz M; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 2006)
This study investigated the role of suckling on the resistance and resilience of lambs during the period - six to 20 weeks after lambing. Eighty, 42-day old twin-born lambs were allocated to four treatment groups in which lambs continued to suckle (S-) or were weaned (W-), while concurrently infected with either 0 (-N) or 1000 (-I) L3 Teladorsagia circumcincta larvae d-1. Faecal egg counts peaked at 680, 1600, 260, and 225 eggs g-1 of fresh faeces in SI, WI, SN and WN lambs, respectively. Live weight gain was reduced from day 98 of age as a consequence of weaning (p<0.001) and infection (p=0.008). Serial slaughter on days 84, 112, and 140 indicated that suckling reduced the number of adult worms in SI compared with WI lambs though significantly so only on day 112 (p<0.05). In vitro larval establishment decreased (p<0.001) with slaughter age but was not influenced by suckling or infection (p>0.05). These results suggest that suckling may inhibit nematode development at a later stage than the immediate entry of incoming L3 larvae. In addition, suckling does not appear to confer greater resilience during T. circumcincta infection in young lambs.

Gene markers for wool fibre traits - Abbott JKR; Hickford JGH; Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 2006)
Selective breeding has been used for thousands of years to improve the quality and weight of wool, but surprisingly there is still a large amount of genetic variation present at the loci involved in the “blueprint” for wool synthesis. This genetic heterogeneity results in considerable variation within, and between individual fleeces. This has both positive and negative implications. Where a wool processor requires uniformity in raw stock, both to gain efficiency in processing and to make a product to specification, it has a negative effect. Where specific traits convey unique properties it opens up opportunities for differentiated products. Markers for genes or knowledge of individual gene effects may be useful for identifying sheep with desirable wool traits that are difficult or expensive to measure under field conditions. The discovery of genetic variation in valuable fibre traits could allow the development of gene-marker tests which would assist breeding for more consistent wool.

Genetic parameters for resistance to facial eczema in dairy cattle - Cullen NG; Morris CA; Hickey SM (Proceedings of the New Zealand Society of Animal Production, 2006)
A project was designed to progeny-test dairy industry sires for their resistance to facial eczema (FE), as a preliminary step towards identifying DNA markers or genes for FE resistance. The FE disease is caused by the toxin, sporidesmin, produced by spores of a fungus, Pithomyces chartarum, found on many pastures in summer and autumn in the North Island of New Zealand. In susceptible animals, sporidesmin causes liver injury, and the cost of FE to the dairy industry is measured in tens of millions of dollars in years with serious outbreaks ($3.6 to 66.2M per annum). Earlier studies in New Zealand have established that resistance to FE in cattle is a heritable trait, with resistance measured by variation in activity in blood of liver-derived enzymes, gamma-glutamyltransferase (GGT) and the associated glutamate dehydrogenase (GDH). Widely used Friesian and Jersey sires were progeny-tested via 572 specially-reared sons (born in 2002-04 and dosed with sporidesmin), and also via 3761 daughters in autumns 2004 and 2005 in 17 herds with 3-22% clinical cases of FE per herd. The data were combined from all sources, including four earlier years of GGT records (1173 animals born in the 1986, 1989, 1990 and 1992 birth years), and standardisation was applied to each contemporary group. Heritabilities were estimated for Friesians (0.47 ± 0.07 for log GGT; 0.32 ± 0.08 for log GDH) and for Jerseys (0.37 ± 0.06 and 0.39 ± 0.09, respectively), and there was a very high genetic correlation between activities of the two enzymes (0.93 ± 0.03). Sixty-eight sires had reliabilities of >0.70 for log GGT Breeding Value and 71 others had reliabilities between 0.60 and 0.70. The sires progeny-tested in this way generally were already proven for dairy traits and had been widely used, so that FE selection among these sires would be an additional trait when they were already old. Alternative approaches would be to performance-test young bulls for FE resistance, or to use sire and progeny data and their DNA to identify DNA markers or genes for FE resistance.

Genetics of stillbirth in dairy calves - Pryce JE; Harris BL; Sim S; McPherson AW (Proceedings of the New Zealand Society of Animal Production, 2006)
The aim of this study was to investigate factors affecting, and estimate variance components of, stillbirth using data collected as part of Livestock Improvement’s Sire Proving Scheme. Only calves that reached full-term of gestation were considered (i.e. abortions and inductions were excluded). After editing there were 773,904 records on calf-fate collected from 1987 to 2004. The mean incidence of stillbirth was 7.2%. The fixed effect model fitted to the data included the effects of contemporary group, birth assistance code, the sex of the calf, the gestation length of the dam, whether the dam was primiparous or multiparous and mating type e.g. a Jersey cow mated to a Holstein-Friesian sire etc. Breed proportions of New Zealand (NZHF) and North American (OSHF) origin Holstein-Friesian and Jersey were also fitted in addition to the proportion of heterosis expected in the calf. Data were analysed by considering stillbirth as a binomial trait using the logit transformation in ASReml that included a sire-maternal-grandsire pedigree. The direct heritability of stillbirth was estimated to be 0.010 (s.e. 0.009). It was not possible to estimate the maternal heritability using this dataset. Estimates of fixed effects were obtained from ASReml by analysing stillbirth as a continuous trait, as back-transformed fixed effect estimates obtained using a binomial model are unreliable when the incidence is small. The largest effect on the probability of stillbirth was calving difficulty. Compared to no assistance at calving, the two categories of greatest calving difficulty resulted in 22% and 41% mortality. The next largest effect on stillbirth was gestation length, with longer gestations being associated with more stillbirths. Males were 1% more likely to be stillborn than females. OSHF were most likely to be stillborn, followed by Jerseys and then NZHF. Heterosis effects were significant and favourable, except between the two strains of Holstein-Friesians where there was no significant heterosis. The largest heterosis estimate was between NZHF and Jerseys. Unlike some overseas programmes, genetically selecting for reduced stillbirths would not be effective in New Zealand, crossbreeding and devising strategies to manage calving assistance and gestation length appear to be more worthwhile.

Genomic technologies to create new opportunities for wool growers - Introductory remarks - Pearson AJ (Proceedings of the New Zealand Society of Animal Production, 2006)
Efficient sheep farming of the future will demandreduced labour costs, ease of shearing, and minimised susceptibility to flystrike, while modern markets simultaneously demand reduced chemical use and high standards of animal welfare. Sheep witha reduced area of the body covered with fleece may provide a practical solution to these conflicting requirements. Research has shown that it is possible to select sheep for bare faces, legs, belly and breech, and that atleast some of these traits behave as though they are controlled by recessive genes, but that some only becomeevident later in life. Patterns of fleece distribution define major skin domains in the sheep that are evident in other mammals. We hypothesise that discrete skin domains arise because fibroblasts that induce wool follicle development originate from different embryonic tissues and carry with them differing developmental programmes for each follicle type. Identifying genes underlying variation in fleece distribution would allow desirable distributions to be established in sheep of diverse genetic backgrounds. Markers for distribution traits would enable us to introgress appropriate genes into flocks that do not carry them, and to determine early in life which animals might express the traits as adults.

Identification of commensal bacterial metabolites that enhance the integrity of the gastrointestinal barrier - Anderson RC; Cassidy LA; Cookson AL; Koulman A; Hurst RD; Fraser K; McNabb WC; Lane G; Roy NC (Proceedings of the New Zealand Society of Animal Production, 2006)
The objective of this research was to identify metabolites produced by commensal bacteria that enhance the integrity of the gastrointestinal barrier (GIB). The integrity of the GIB is mainly determined by the complexity of interactions between tight junctions of opposing epithelial cells of the GI wall. This was measured using an in vitro bioassay, consisting of a monolayer of intestinal epithelial cells grown on a membrane. The trans-epithelial electrical resistance (TEER) across this monolayer was measured to determine the strength of the tight junctions. Preliminary results showed that a commercial probiotic product caused an increase in TEER across non-differentiated and differentiated monolayers by 178 ± 61% and 40 ± 9%, respectively. The maximum increases in TEER obtained with conditioned media fractions (media fractions containing components secreted by the probiotic product) was between 23 ± 6% and 43 ± 4%. The conditioned media fraction containing components less than 3 kDa accounted for the total activity of the whole conditioned media. Metabolite profiling of active conditioned media compared to inactive conditioned media using fast-LCMSMS identified numerous metabolites that may be responsible for this positive effect. Future work will isolate the candidate metabolites and screen them for GIB enhancing activity both in vitro and in vivo.

Impaired insulin secretion in perfused pancreases isolated from offspring of protein malnourished rats - Barnett MPG; Phillips ARJ; Harris PM; Cooper GJS (Proceedings of the New Zealand Society of Animal Production, 2006)
Insufficient maternal protein intake may contribute to changes in carbohydrate metabolism and subsequent diabetes mellitus in adult mammalian progeny. Here, female rats (a model of mammalian metabolism) were fed throughout pregnancy and lactation with otherwise-complete isocaloric diets sufficient (20% whey protein, control (C)) or insufficient (5% whey protein, low-protein (LP)) in protein. From weaning, all offspring ate diet C. Weight gain of LP mothers during gestation was less than C mothers (C: 117 g vs. LP: 78 g, SED = 9, P

In vitro production of volatile fatty acids from forages - Burke JL; Waghorn GC; Brookes IM; Chaves AV; Attwood GT (Proceedings of the New Zealand Society of Animal Production, 2006)
Volatile fatty acid (VFA) production from a range of fresh forages was measured in vitro over 24 hours (h). The forages comprised temperate and tropical grasses, legumes (including some containing condensed tannins; CT), herbs and silages, all of which were minced to resemble chewed forage and incubated in buffered media. Volatile fatty acid concentrations were measured in triplicate for each feed at 0, 6, 12 and 24 h. On average, VFA yields were 131, 226 and 311 mg/g dry matter (DM) between 0 - 6, 0 - 12 and 0 - 24 h, and the highest yields were from legumes (384 mg/g DM) and lowest from plantain (176 mg/g DM) after 24 h. Legumes containing CT produced 28% less VFA than other legumes. The acetate + butyrate:propionate (A+B:P) ratio showed a substantial difference between forage types, ranging from an average of 2.5 (legumes) to 3.5 (tropical grasses) after 6 h, but differences between forage types diminished after 24 h. Multiple regression analysis showed a weak inverse relationship with NDF (neutral detergent fibre) after 6 h, but there was no clear relationship with particle size, chemical composition or digestion rates at 12 and 24 h.

Increased hepatic skatole exposure via rumen infusion increases skatole concentration in peripheral circulation and inter-muscular fat in sheep - Deighton MH; Pacheco D; Tavendale MH; Schreurs NM; Peters JS; McNabb WC; Roy NC (Proceedings of the New Zealand Society of Animal Production, 2006)
Skatole meat taint is unique to pastoral systems where high forage digestibility results in tryptophanderived skatole production at rates that exceed the clearance capacity of the liver. We hypothesise that under conditions of minimal endogenous skatole production (diet low in rumen degradable protein) a continuous rumen infusion of skatole will elevate hepatic exposure and modify tissue skatole metabolism. A 72 hour rumen infusion of skatole (140 mg/h; n = 6) dissolved in propane-1,2-diol (PD) or PD media alone (n = 6) was performed. Samples of rumen fluid and blood were collected at 0, 2, 4, 6, 8, 12, 16, 24, 48 and 72 hours for determination of skatole concentration. Infusion of skatole increased (P < 0.01) levels of skatole in rumen fluid (21 µg/g), peripheral plasma (154 ng/ml) and inter-muscular fat (4240 ng/g). A two-compartment model was fitted to the rumen and plasma skatole concentration of treated sheep to estimate the rate of transfer from rumen to peripheral plasma (k = 0.23 ± 0.03/h) and the rate of elimination from peripheral circulation (k = 2.10 ± 0.56/h). A negative correlation (P < 0.05) between the rate of elimination and level of skatole deposition in inter-muscular fat was also found.

The influence of red deer genotype on conception pattern : Eastern vs Western subspecies - Scott IC; Asher GW; Lach JE; Littlejohn RP (Proceedings of the New Zealand Society of Animal Production, 2006)
Advancing the calving pattern of red deer from November/December to October/November would better align the nutritional demands of lactation to pasture quality and availability. This study investigated the hypothesis that red deer of ‘Eastern’ (E) genotype (Cervus elaphus hippelaphus) have advanced reproductive seasonality traits compared to those of ‘Western’ (W) genotype (C. e. scoticus). Hinds of E (135) or F1 (E x W; 165) genotype were single sire mated to one of 6 E stags, while W (506) hinds were single sire mated to one of 11 W stags. Reproductive seasonality traits measured were stag roaring and body condition score (BCS), and conception date as estimated by fetal aging. Peak roaring frequency occurred earlier in E than W stags (mean March total roars observed 144 vs. 68 for E and W stags respectively; SED 33.4; P

Lessons from the national anthelmintic resistance surveys - Pomroy WE (Proceedings of the New Zealand Society of Animal Production, 2006)
Dexcel's Whole Farm Model (WFM) is a computer model of a dairy farm that simulates individual cows and paddocks, with pasture growth driven by observed climate data and with management policies guiding decisions on a daily basis. The aim of the study was to design a farm system to produce 1750 kg milksolids (MS)/ha/yr from feed grown on-farm. An average predicted pasture growth curve was derived by initialising the WFM for a typical all-pasture Waikato farm (3 cows/ha) with "best practice" management policies and running the simulation for 29 years of Ruakura climate data. The model was then used with this average growth curve to design the high producing system. Pasture growth alone (17.3 t DM/ha) did not fulfil the feed requirement for the 1750 kg MS/ha scenario, with an overall feed deficit of 3.1 t DM pasture/ha. Improvements in ryegrass cultivars and N-fertilisers could be expected to increase pasture production by around 10%, reducing the overall feed deficit to 1.6 t DM pasture/ha. These improvements together with irrigation at 2 mm/day over the three summer months (Dec - Feb) reduced the feed deficit to zero. Irrigation could be replaced by cropping between 11%and 20% of the farm in a rotation of annual ryegrass yielding 7 t DM/ha and maize yielding 22 to 28 t DM/ha respectively.

Management and reproductive performance in herds that differed in their induction policies - Compton CWR; McDougall S (Proceedings of the New Zealand Society of Animal Production, 2006)
A large scale retrospective study was undertaken in 2005 on the impact of the policies for induction of early calving (either undertaken during study period, stopped in previous 2 seasons, or continuing to induce) and other factors on herd reproductive performance. Data was gathered from whole-herd pregnancy testing data and farm visit records, and electronic records from the LIC database. Data analysed included records from 3 consecutive seasons from 82 herds, and included 34,729 cows, 72,593 calvings, 237,884 individual herd test records and summary pregnancy test results for each herd for 3 seasons. Factors that significantly influenced herd reproductive performance were herd induction policy, season, herd predominant breed, 4 week submission rate, average milk protein percent at herd test within 60 days following the start of the breeding programme, and length of breeding programme (all P< 0.01). Induction usage was found to be declining over time, implemented at a later stage of the calving programme and unlikely to meet Code of Practice requirements, and under-reported to the LIC database. This large-scale epidemiologic study provides important information for herd owners, their advisors, and other scientists on herd reproductive performance.

Mastitis in cows milked in an automated or conventional milking system in New Zealand - Lopez-Benavides MG; Williamson JH; McGowan JE; Lacy-Hulbert SJ; Jago JG; Davis KL; Woolford MW (Proceedings of the New Zealand Society of Animal Production, 2006)
The viability of automated milking systems (AMS) for pasture-based dairying has been studied in New Zealand in the past four years. Automatic milking differs from conventional milk harvesting systems (CMS) in a number of ways, which may impact on udder health. These include fewer machines/cow, distributed vs. batch milking, variable milking intervals, automatic udder health monitoring systems, and pre and post-milking teat sanitation procedures. Three seasons of data from two pasture-based research farms that milked cows with either a two unit AMS or a 30 bail rotary CMS were compared. Quarter milk samples were collected routinely from all cows for bacteriological analysis during the 2002-03, 2003-04 and 2004-05 seasons, with sampling occurring throughout lactation and at detection of clinical mastitis (CM) cases. The number of cows in the AMS herd ranged from 94 to 196 and in the CMS herd, from 289 to 324 across the seasons. Clinical mastitis affected 7, 11, and 15 cows/100 cows/season in the AMS herd and 24, 23 and 14 cows/100 cows/season in the CMS across the three seasons, with Streptococcus uberis isolated from approximately 50% of CM cases from both herds. Prevalence of S. uberis post-calving averaged 8% of cows for the AMS and 16% for the CMS across the three seasons. We compared several indicators of udder health between an AMS and a CMS herd managed under pastoral conditions.

Metabolomics for animal production : An introduction - Koulman A; Roy NC (Proceedings of the New Zealand Society of Animal Production, 2006)
Metabolomics will be one of the most important tools in the exploitation of the bovine genome sequencing project. The results of metabolomics will play important roles in many facets of animal production. This paper will give an introduction of metabolomics and its application in the field of animal production. It serves as the start of the metabolomics session at the 2006 conference of New Zealand Society of Animal Production covering the origin, analytical chemistry and ongoing research in metabolomics with a special focus on this research within New Zealand.

Methane emissions from growing beef cattle grazing hill country pasture - Molano G; Clark H; Knight TW; Cavanagh A (Proceedings of the New Zealand Society of Animal Production, 2006)
Methane (CH4) emissions from 12 Hereford x Friesian steers grazing hill country were measured on six occasions (6, 11, 13, 15, 23, and 26 months of age) during the months of February, July, September, November 2003, and October and November 2004 using the sulphur hexafluoride (SF6) tracer gas technique. These data are the first serial measurements of CH4/kg DMI on growing dairy beef cattle in New Zealand. Average daily methane (± s.d.) emissions increased from 89 (10) g/head/d for 6 month old steers to 222 (46) g/head/d for 26 month old steers. The corresponding dry matter intake (DMI), predicted from energy requirements using the Feeding Standards for Australian Livestock, also increased from 3.6 kg/head/d to 12.0 kg/head/d for 6 and 26 month old steers, respectively. In contrast to the increasing DMI and daily methane emissions with age of the steers, the mean methane emission per unit of estimated intake was relatively constant at 17.3 (3.7) to 19.0 (5.6) g CH4/kg DMI from 11 to 26 months of age with a higher value of to 26.1 (7.0) g CH4/kg DMI for the 6 month old steers. The overall mean value of 19.5 (± 5.2) g CH4/kg DMI is lower than that used in the current national inventory calculations.

Micro-arrays as a discovery tool for wool genomics - Yu Z-D; Bawden CS; Henderson HV; Nixon AJ; Gordon SW; Pearson AJ (Proceedings of the New Zealand Society of Animal Production, 2006)
Wool follicle development and growth is a highly ordered and complex process involving the sequential expression of numerous genes within diverse cell populations. The aim of present studies using microarray analysis is to identify genes and pathways involved in the growth of wool follicles which could be utilised to increase farm productivity and improve the characteristics of Australasian wools. An ovine cDNA array was developed including sequences derived from sheep skin containing wool follicles in different growth stages encompassing many structural and regulatory genes necessary for follicular growth. Initial comparison of stages of wool follicle regression show marked changes in the expression levels of numerous genes including wool keratins. Two parallel research projects in Australia and New Zealand supported by SheepGenomics are currently utilising microarray technology to profile gene expression during key stages of wool follicle development in the foetus and follicular cycling associated with fleece shedding.

Microbial metabolomics towards fibre digestibility in the rumen - Villas-Boas SG; Noel S; Lane G; Attwood G; Cookson A (Proceedings of the New Zealand Society of Animal Production, 2006)
Milking cows for two consecutive years, with calving and mating occurring every second year, may exploit the superior lactation persistency of high yielding cows while improving reproductive performance. This study tested the feasibility of extended lactations in pastoral systems using divergent dairy cow genotypes (New Zealand [NZ] or Overseas [OS] Holstein-Friesian [HF]) and levels ofnutrition (0, 3, or 6 kg concentrate DM/cow/day). Cows calved on 28 July 2003 and remaining cows were dried off by 6 May 2005. Of the 56 cows enrolled, 93% were milking at 500 daysin milk (DIM) and 18% were milking at 650 DIM. Dietary treatments did not affect DIM (605 ± 8.3; Mean± SEM), but there was a trend (P=0.09) for OS HF to have longer lactations than NZ HF. Genotype x diet interactions were detected for the total yield of milk and milksolids per cow, and as a percentage of liveweight. Differences between genotypes were greatest at the highest level of supplementation. Compared to NZHF, OS HF produced 35% more milk, 24% more milk fat, 25% more milk protein, and at drying off had 1.9 units less body condition. Annualised milksolids production from NZ HF was 79% of a normal season’s production, compared to OS HF that produced 94%. Compared to NZ cows, OS cows had a similar 21-day submission rate (85%), a lower 42-day pregnancy rate (56% vs. 79%), and a higher final empty rate (30 vs. 3%) when mated at 451 days after calving. These results indicate that productive extended lactations up to 650 days are biologically possible on a range of pasture diets, and with appropriate cow genetics and feedmanagement may ameliorate poor reproductiveperformance in high yielding dairy cows without sacrificing milksolids production

Milk production in Romney ewes lambing out of season - Peterson SW; Morel PCH; Kenyon PR; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2006)
Milk yield (MY) of groups of Romney ewes lambing at 3 times of the year: January (n=9), March (n=14) and June (n=13)) was measured on alternate days in the first week postpartum and at weekly intervals for nine weeks. Twin-bearing ewes produced significantly more milk than single-bearing ewes during the first week and during the whole of lactation (63 days) (P<0.05), except in the January-lambing group, in which ewes with single lambs produced more milk then those with twins during the first week. The shape of the lactation curve for ewes with singles or twins differed significantly (P<0.01) between lambing groups, reflecting that single- and twin-bearing ewes responded differently in January, but the number of twinbearing ewes was small (n=4) in that month. MY differed significantly (P<0.01) among groups lambing in January (single MY ± SEM: twins MY ± SEM) (1605 ± 57: 1402 ± 71 g/d), March (1425 ± 38; 1802 ± 46) and June (1520 ± 43: 1951 ± 54). Despite having the lowest (P<0.05) mean pre-lambing live weight (62 ± 3 kg), ewes lambing in June produced the highest overall mean MY (1735 ± 48 g/d), whilst ewes lambing in March and January had mean pre-weaning live weights of 70 ± 2 kg (in both groups) and produced 1613 ± 42 g/d and 1504 ± 64 g/d respectively. The June–lambing ewes gained weight (1.38 ± 1.19 kg) and condition score (0.39 ± 0.16 /d) whilst weight loss was significant (P<0.05) in the March (-9.82 ± 1.15 kg) and January (-7.78 ± 1.44 kg) groups between pre-lambing and weaning, as was change in condition score (March: -0.49 ± 0.16; January: -0.63 ± 0.19). Lamb birth weights did not differ between seasons but ADG (g/d ± SEM) was highest (P<0.01) in June (0.262 ± 0.008), followed by March (0.238 ± 0.008) and January (0.202 ± 0.009).

Mycotoxin poisoning in grazing livestock in New Zealand - Towers NR (Proceedings of the New Zealand Society of Animal Production, 2006)
A number of mycotoxicoses including facial eczema, ryegrass staggers, paspalum staggers and zearalenone infertility affect grazing livestock, causing death and reducing productivity. While production losses associated with clinical disease are well recognised, losses associated with subclinical disease are not recognised and most farmers take few or no precautions against the diseases and consequently accept lower productivity levels as `normal`. For most mycotoxicoses there are no antidotes. Long-term research projects, some lasting decades, have led to the development of a number of control measures for particular diseases, especially facial eczema and ryegrass staggers. These measures depend primarily on identifying and avoiding toxic pastures, or reducing their impact. Under the current funding regimes, where funders seek quick returns, it is unlikely that many of these now widely used control methods would have come to fruition.

Mycotoxins in New Zealand livestock production - Morris CA (Proceedings of the New Zealand Society of Animal Production, 2006)
An extended period of reproductive inactivity (anoestrus)is part of the normal recovery process in dairy cows, following calving. Low body condition at calving and long periods of negative energy balance affects the length of the post-partum anoestrous interval (PPAI). This study examined the effect of feeding two different supplementary feeds through early lactation, on the length of the post-partum anoestrous period. Forty-five mature dairy cows were allocated to either pasture (P; pasture allowance of 35 kg DM/cow/day), pasture plus a cereal (P+C; 3.0 kg/cow/day maize & barley; 50%: 50%) or pasture plus a lipid supplement (P+L; 1.8 kg/cow/day lipid-based supplement, plus 180 ml/cow/day oil drench 33% fish oil: 67% linseed oil), starting in the first week post-calving and continuing for at least 7 weeks (range 7 to 15 weeks). The length of the anoestrous period was measured using twice weekly milk progesterone analyses, ending on the 8th October, 2004. An animal was identified as having ovulated when milk progesterone concentrations reached a threshold (>3ng/ml), this event was categorised as the initial ovulatory event (IOE). There was no effecton the interval from calving to IOE (35.7±3.9 days, 32.8±2.9 days, and 35±3.9 days; mean±SEM) for P, P+C and P+L groups, respectively. There was no effect of supplementation on either live-weight and body condition changes through early lactation. This study showed that when mature cows are fed a generous allowance of pasture post-calving, providing a cereal or lipid-based supplement during early lactation did not reduce the length of the PPAI.

A nutrient-signalling effect of grain feeding on postpartum anovulatory intervals in mature dairy cows - Burke CR; Roche JR; Aspin PW; Lee JM (Proceedings of the New Zealand Society of Animal Production, 2006)
Our previous study with mature dairy cows found that increased pasture intakes in early lactation resulted in more milk being produced but with no change in postpartum anovulatory intervals (PPAI). The present study used a 2 x 2 factorial to determine PPAI in 68 cows with pre- and post-calving diets that were iso-energetic, but varying in the ratio of structural to non-structural carbohydrate. At 36 ± 8.7 days prepartum, cows were assigned iso-energetic diets (114 MJ ME/cow/day) of either pasture/pasture silage (n=34) or the same diet supplemented with 3 kg DM/cow/d barley-maize concentrate (n=34). After calving, cows within each prepartum diet were assigned iso-energetic diets (179 MJ ME/cow/d) of either pasture/pasture silage (n=34) or the same diet supplemented with 5 kg DM/cow/d concentrate (n=34). Postpartum grain feeding reduced (P < 0.05) PPAI (28.4 ± 1.8 day) compared to the pasture/pasture silage only diet (36.4 ± 2.5 day). Prepartum diet did not affect PPAI. Body condition score was inversely related to PPAI at all time points (P < 0.05), but explained little (5-12%) of the variability in PPAI. Significant relationships to PPAI were also found for blood non-esterified fatty acids, urea and magnesium, but again, r2-values were ≤ 0.1. None of the milk characteristics measured were significantly related to PPAI. This study supports the premise that discrete or specific nutritional cues unrelated to general energy status can favourably target physiological functions in reproductive tissues at the brain and/or ovarian levels.

Options for change within the wool supply chain - McDermott AK; Sumner RMW; Scobie DR (Proceedings of the New Zealand Society of Animal Production, 2006)
Supply chains are the channels along which products flow from producer to processors and manufacturers, distributors and retailers until final consumers purchase them. The businesses along the chain are linked through the transactions between them and the information that they share. Wool is an inherently variable product that cannot be adapted quickly to changes in processor’s requirements. As such it is a weak competitor in a section of the global textile marketplace dominated by synthetic textiles derived from petrochemicals. Nevertheless, wool has unique functional advantages over most synthetic fibres. Efficient supply chains are dependent on effective relationships between stakeholders. Reduction of costs incurred along the supply chain requires investment in horizontal and/or vertical relationships to improve information transfer between stakeholders, or to benefit from economies of scale and/or scope. Improved information transfer strengthens stakeholder confidence enabling the development of innovative business initiatives.

Plasma insulin, growth hormone, and IGF-1 concentrations of Holstein - Friesian cows of divergent genotype offered varying levels of concentrate in early lactation - Kolver ES; Roche JR; Aspin PW (Proceedings of the New Zealand Society of Animal Production, 2006)
This study of insulin and key hormones of the somatotropic axis was made to help explain the milksolids and body condition responses obtained from cows of divergent Holstein-Friesian (HF) genotypes fed differing levels of concentrate. Weekly plasma concentrations of insulin, insulin-like growth factor-1 (IGF-1) and growth hormone (GH) were measured from 57 North American (overseas; OS) and New Zealand (NZ) cows in the first 10 weeks of lactation during the 2002/03 and 2003/04 seasons. Cows of similar breeding worth grazed at a high pasture allowance and were individually fed 0, 3 or 6 kg concentrate DM/cow/day. Compared to NZ HF, OS HF had similar insulin concentrations, lower IGF-1 concentrations, and higher GH concentrations. Feeding 3 or 6 kg concentrate DM/day increased insulin and IGF-1 concentrations to a similar extent, with GH concentrations being reduced at the highest level of supplementation. These results are consistent with the previously reported greater loss of body condition in OS HF, and suggest genotype differences in insulin resistance and rate of recoupling of the somatotropic axis after calving. The reported gain in body condition when concentrates were fed is probably a result of the increased insulin production and a positive effect on liver GH receptor 1A, with the consequent increase in IGF-1 and reduction in GH. Diet only began to affect GH concentrations, and therefore body condition loss, after approximately week 4-6 of lactation. These results have implications for feed management and breeding.

Plasma protein loss in lambs during a mixed infection of Trichostrongylus colubriformis and Teladorsagia circumcincta - a consequence of the immune response? - Vaughan AL; Greer AW; McAnulty RW; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 2006)
Modelling is being used to compare and contrast farm management strategies. A Whole Farm Model (WFM) has been developed that links models for cow metabolism (‘Molly’) and pasture growth driven by climate, with management policies. It has been evaluated against trial data and the challenge is to now use it for prediction. This requires that cows be initializedso that their production is determined by their environment and genotype. Livestock Improvement Corporation has developed a system of quantifying genotype through production values (or PV's). The aim of this study was to assess the ability of the WFM to predict Strain Trial cow production using PVmilk. The relationship between PVmilk and milk yield and composition was determined by allowing a parameter within ‘Molly’ to adjust so that predicted matched actual production for 3 Strain herds and one Jersey herd. WFM was then initialized using observed PVmilk to set genotype of each cow in 8 other Strain herds and farmlets were simulated for 2003/04 season. Predictions were considered useful if the prediction errors for milk yield and milksolids (629 L and 61 kg MS respectively) were lower than the observed standarddeviations (825 L and 66 kg MS respectively) i.e. meaning model predictions of observed values were more accurate than simply using the mean as an estimate of observed values. The consistent under-prediction of milk yield and milksolids require further adjustments to the initialization of the model. PVmilk has the potential to set genotype in ‘Molly’, within the WFM.

Predicting cow production based on an estimate of animal genotype within a whole farm model - Beukes PC; Palliser CC; Lancaster J; Leydon-Davis C; Levy G; Folkers C; Macdonald K; Thorrold BS; Montgomerie B; Wastney M (Proceedings of the New Zealand Society of Animal Production, 2006)
Body condition score (BCS) has been proposed for inclusion in the New Zealand national dairy index, Breeding Worth (BW), to account for replenishment of body tissue. Currently, the breeding objectives model positively accounts for body tissue mobilisation (through extra yield), but not the negative cost of replenishing body tissue. Two methods have been proposed: 1) Including BCS directly into BW by calculating and assigning an economic value to BCS and 2) Adjusting liveweight Breeding Values (BVs) for BCS, which would mean that liveweight BVs would beexpressed at a constant BCS (indirect method). Energy equations were used to calculate the direct economic value for BCS and included a sensitivity analysis. With an economic weight of $25, the percentage emphasis of BCS in BW would be 3.4%. Including BCS in BW, either directly or indirectly, had little impact on sire rankings (rank correlations with and without BCS within breed were >0.99) and would only have a small impact on the economic response of BW ($0.02 net /cow/annum) and the improvement in BCS(0.006 BCS units/cow/annum). It is concluded that there would be little benefit to including BCS as an independent trait in BW. Body condition score is already included as a predictor in the genetic evaluation of fertility and breeding values for BCS will be estimated routinely from the fertility model.

Preliminary survey of congenital and reproductive disorders in the New Zealand miniature horse population - Rogers CW; Gee EK; Hangoor E; Firth EC (Proceedings of the New Zealand Society of Animal Production, 2006)
The Miniature horse population is a rapidly expanding sector of the New Zealand (NZ) equine population. It is estimated that there have been 6,052 Miniature horses registered in NZ, with 677 new registrations in 2004. The lay literature implies that the Miniature horse breed has a high level of reproductive and congenital defects. To obtain reference data on the reproductive and congenital disorders of the NZ Miniature horse breed a face-to-face survey was conducted with 22 breeders located in the lower North Island of NZ. The 22 breeders were the owners of 421 horses (246 mares, 52 stallions, 88 foals and 35 geldings). The mean number of Miniature horses on the property was 19 horses (range 4-60), 11 broodmares (range 2-30) and 2 stallions (range 0 ¨C 8). Most horses (75%) were registered with the NZ Miniature horse Association or the American Miniature Horse Society (23%). Most Miniature horses were type A, being ≤86cm in height at the withers (72%). The average foal crop per breeder was 7 foals, which were conceived with hand serving (61.4%) or a combination of hand serving and having the stallion run with the mare (31.8%).Confirmation of pregnancy was by blood test (49.2%), ultrasound verification (19%), combination of blood test and ultrasound (6%), or non return to oestrus (23.4%). Seventeen breeders had mares that were covered by the stallion during the season but did not return a positive pregnancy (23.4% of mares covered in the season). There was a lower percentage of apparent fetal loss on farms that used blood tests or ultrasound to verify pregnancy compared to farm relying on non return to oestrus(10.38% ± 2.49% vs. 20.79% ± 4.59%, p=0.06).The incidence of fetal abortion (<300 days gestation) was 1.75% (CI 0.5-3.03), and 5.2% (CI 2.6 -7.8%) of mares suffered from dystocia. The incidence for premature placental separation was 0.82% (CI 0.26-1.39%) and the incidence of retained placenta was 1.4% (CI 0 -3.6%). The incidence of dwarfism was 0.7% (CI 0.11-1.28%), with 11 breeders reporting foals that had excluded from the studbook due to dwarfism. The incidence of parrot and sow mouth was 1.22% (CI 0 -2.43%) and 0.45% (CI 0- 0.84%), respectively. The incidence of respiratory disorders (including signs indicative of collapsed trachea and cleft palate) was 2.2% (CI 0.7 -3.7%). The data collected indicate that the incidence of reproductive and congenital disorders in the New Zealand Miniature horse population is lower than expected.

Presidential Address 2005: Animal production - the bridge between animals on the farm and the consumer - Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 2006)
The development of man from caveman to the sophisticated being that he is today has been dependent on us using the animals and plants surrounding us as a source of food, warmth and shelter. As we have developed so we have mastered the management of these resources to make life more comfortable. In managing these resources we have developed ways and means of manipulating animals and plants in various ways to produce special products.

Prevalence of mastitis for cows of different genotypes milked for two consecutive seasons - Lacy-Hulbert SJ; Summers EL; Williamson JH; Aspin PW; Kolver ES (Proceedings of the New Zealand Society of Animal Production, 2006)
Extending the calving interval from the traditional 12-month to a 24-month calving interval has been suggested as a practical solution for maximizing lactation yield per calving. Somatic cell count (SCC) and the incidence of mastitis were examined in New Zealand (NZ) and overseas (OS) Holstein-Friesian cows fed on pasture alone or supplemented with 3 or 6 kg DM maize/barley concentrates/cow/day during an extended lactation of up to 21 months. Average cow SCC was three-fold higher (P<0.001) in the extended or second season of the lactation compared with the first season, with NZ cows having a slightly higher SCC (P<0.01) in the second season compared to OS cows (191,000 and 115,000 cells/ml respectively). The SCC elevations occurred regardless of infection status of the udder. Although OS cows tended to have twice as many cases of clinical mastitis (P=0.01) in the first season compared to the NZ cows, affecting 59% and 27% of cows respectively, there was no difference in infection status between genotypes in the second season (20% and 18% respectively). Results showed that although cows experienced less mastitis during the second spring of the lactation, the average cow SCC was higher during the extended part of the lactation.

A profile of anthelmintic resistance and parasite control practices in New Zealand - results from a 2005 survey - Rhodes AP; Leathwick DM; Pomroy WE; West DM; Jackson R; Lawrence K; Moffat J; Waghorn TS (Proceedings of the New Zealand Society of Animal Production, 2006)
Anthelmintic (drench) resistance in New Zealand’s ruminant livestock is arguably the biggest single threat to sustainable future pastoral production. Clinical and sub-clinical parasitism impacts not only on animal health, but on animal welfare, and hence the image of pastoral production systems, total production and production efficiency and has a marked impact on the economic bottom line for both farmers and the country as a whole. In 2001 it was estimated for the relatively small NZ deer industry alone (worth $311 million in export earnings) that parasitism cost $12.8 million per annum in production losses due to parasitism and parasite control (Mackintosh and Wilson, 2002).

Protein fractionation prototype to extract minor proteins on-farm - Chand A; Fee CJ (Proceedings of the New Zealand Society of Animal Production, 2006)
The aim of this study was to investigate factors affecting, and estimate variance components of, stillbirth using data collected as part of Livestock Improvement’s Sire Proving Scheme. Only calves that reached full-term of gestation were considered (i.e. abortions and inductions were excluded). After editing there were 773,904 records on calf-fatecollected from 1987 to 2004. The mean incidence of stillbirth was 7.2%. The fixed effect model fitted tothe data included the effects of contemporary group, birth assistance code, the sex of the calf, the gestation length of the dam, whether the dam was primiparous or multiparous and mating type e.g. a Jersey cow mated to a Holstein-Friesian sire etc. Breed proportions of New Zealand (NZHF) and North American (OSHF) origin Holstein-Friesian and Jersey were also fitted in addition to the proportion of heterosis expected in the calf. Data wereanalysed by considering stillbirth as a binomial trait using the logit transformation in ASReml that included a sire-maternal-grandsire pedigree. The direct heritability of stillbirth was estimated to be 0.010 (s.e. 0.009). It was notpossible to estimate the maternal heritability using this dataset. Estimates of fixed effects were obtained from ASReml by analysing stillbirth as a continuous trait, as back-transformed fixed effect estimates obtained using a binomial model are unreliable when the incidence is small. The largest effect on the probability of stillbirth was calving difficulty. Compared to no assistance at calving, the two categories of greatest calving difficulty resulted in 22% and 41% mortality. The next largest effect on stillbirth was gestation length, with longer gestations being associated with more stillbirths. Males were 1% more likely to be stillborn than females. OSHF were most likely to be stillborn, followed by Jerseys and then NZHF. Heterosis effects were significant and favourable, except between the two strains of Holstein-Friesians where there was no significant heterosis. The largest heterosis estimate was between NZHFand Jerseys. Unlike some overseas programmes, genetically selecting for reduced stillbirths would notbe effective in New Zealand, crossbreeding and devising strategies to manage calving assistance and gestation length appear to be more worthwhile.

Quantitative genetic selection for twinning rate in ewes - Amer PR; Bodin L (Proceedings of the New Zealand Society of Animal Production, 2006)
Data from 19 recorded sheep flocks were included in this study involving 324 thousand lambings from the 1970’s up until the 2004 lambing season. The genetic correlation between number of lambs born, and a triplet trait coded as 1 for ewes lambing triplets or higher multiples, and 0 for ewes lambing singles or twins was estimated separately over 13 data sets. Genetic correlation estimates ranged between 0.78 and 0.95 with all but two dataset estimates differing from 1.00 by two or more standard error intervals. Flock differences in the relationship between mean NLB and the proportion of ewes lambing twins were also investigated through an analysis of sire mean results. Strong evidence was found for within flock genetic variation in twinning incidence that is independent of mean NLB. This is different to the clear relationship that exists between mean litter size of a group of ewes and the proportion that lamb twins. There were also meaningful differences across-flocks in the proportions of ewes lambing twins after accounting for the effects on twinning percent of flock mean litter size. Our analyses suggest that simple selection strategies such as screening in twin lambing ewes from a commercial flock, and/or, only using twin-born rams in the breeding flock, will be relatively ineffective for improving twinning rates. A recommendation arising from the study is that genetic evaluation tools for twinning be made available to New Zealand sheep breeders. These tools would allow breeders to select for decreased triplets without compromising genetic progress in other traits including mean number of lambs born.

Responses and factors affecting intramammary infection rates resulting from infusion of a Streptococcus uberis strain in Friesian - Jersey crossbred cows - Sanders KM; McDougall S; Stanley GE; Johnson DL; Spelman RJ; Harcourt SJ (Proceedings of the New Zealand Society of Animal Production, 2006)
The objective of this study was to investigate responses to an intramammary infusion of a Streptococcus uberis strain in 264 Friesian-Jersey cows, and identify factors contributing to clinical mastitis risk in the week following infusion. Factors examined for their contribution to risk include sire, days in milk at the time of infusion, SCC on the morning of infusion, previous mastitis treatment history, and the presence of any major pathogens at the time of infusion. Prior to infusion, milk samples were collected from all glands for bacteriology assessment, and antibiotic treatments were administered to clear infections. A single gland from each cow was infused with an average 104 colony-forming units (sd=22) of Streptococcus uberis, and milk samples were collected at each milking for the subsequent 13 milkings, or until diagnosis of clinical mastitis. Logistic regression and survival analysis were used to determine risk factors. Findings showed that cows with a somatic cell count at infusion of ≥100,000 cells/ml had a lower incidence of clinical mastitis (18.3% vs. 81.5%; p<0.0001). Results also indicated that the presence of Staphylococcus aureus at infusion for cows that had no pre-infusion mastitis treatment(s) was associated with a lower incidence of clinical mastitis (29.0% vs. 82.8%; p<0.0001).

Review of zearalenone studies with sheep in New Zealand - Smith JF; Morris CA (Proceedings of the New Zealand Society of Animal Production, 2006)
Zearalenone is a naturally occurring mycotoxin from the Fusarium fungus which grows on pastures in New Zealand in autumn, and it has been found on farms in some years from Northland to Southland. The toxin may interfere with oestrogen-related functions in sheep during reproduction, reducing ovulation rates and fertility and thus lambing percentages, because its chemical structure is similar to that of reproductive steroids. Forty four per cent of over 6000 New Zealand pasture samples, collected in autumn and tested for zearalenone, were found to have high enough levels for ewe fertility to be either depressed (9% of samples), or `at risk` (35%). Control of zearalenone toxin production or of Fusarium growth on pasture on a large scale is currently not feasible. Attempts to mitigate its effects by immunisation have failed or even exacerbated the problem. Provision of alternative zearalenone-free feed crops is costly and generally uneconomic. Selection of sheep for genetic resistance would seem to be the most beneficial approach. Resistance to zearalenone is inherited in sheep (heritability estimate = 0.32 ± 0.10), and a test could be set up in ram-breeding flocks to select for resistance.

Sensitivity analysis of weaner lamb production in New Zealand - Morel PCH; Kenyon PR (Proceedings of the New Zealand Society of Animal Production, 2006)
Many factors contribute to the profitability of sheep farms. A sensitivity analysis, using a simulation model, was conducted to investigate the impact of changes in pasture growth, ewe live weight, conception rate, ewe prolificacy (EP), lamb survival, lamb growth rate and lamb price on farm gross margin (FGM). The model simulated herbage growth and flock energy requirement on a daily basis over a one-year period starting on the 1st January and calculated gross margins for a 500 ha farm, using average Manawatu herbage growth rates. Ewe energy requirements were calculated as a function of live weight, lambing percentage, week of pregnancy or lactation and milk production and lamb energy requirements as a function of live weight, growth rate and body composition. The pre-weaning survival rate and lamb daily growth rate were adjusted for litter size. For each simulation, stocking rates were adjusted so that the pasture cover at the beginning and the end of the year was 1200 kgDM/ha. Simulations were conducted for different farm productivity levels (‘Low’, ‘Medium’ and ‘High’). Results of the simulations show that, over all farm productivity levels, lamb price and growth rate had the largest impact on FGM followed by ewe liveweight, EP, conception rate and herbage growth. However, the ranking and the effect of these parameters on FGM varied across farm types. For example in "Low productivity farms" a 1 % increase in lamb growth rate has the same impact on FGM as a 1 % increase in EP (+$5.4 / ha vs +$5.9 / ha) and in "High productivity farms" a 1 % increase in lamb growth rate is equivalent to a 3 % increase in EP (+$11.2 / ha vs +$11.1 / ha). This illustrates that for each specific farm production level there are different management strategies to optimize FGM. It was also found that the relationship between EP and FGM was not linear. Across the liveweight ranges a one percent increase in EP between 140% and 160% increases FGM by $3.95 /ha, between 160% and 180% by $2.51 /ha, between 180% and 200 % by $1.33 /ha, between 200% and 220% by $2.83/ha, and between 220% and 240% by $2.33/ha. Simulation models can be useful tools when considering farm management decisions as they help identify optimal management systems and identify areas that may require further research.

Sheep and deer grazing of pasture close to cattle dung pats - Trotter CG; Nicol AM; Ridgway MJ (Proceedings of the New Zealand Society of Animal Production, 2006)
An experiment compared the grazing of deer and sheep on pasture with or without contamination by cattle dung pats. Sheep (35 ewes) and deer (24 hinds) separately grazed 0.4 ha plots of a ryegrass/white clover pasture. Half of the area (4 subplots) was contaminated with artificially applied cattle dung pats (DP), 30 cm in diameter, using fresh cattle dung at an application rate of 1 dung pat per 4 m2. The remaining four subplots were left uncontaminated (NDP). Mean pasture mass was estimated daily (rising plate meter) on DP and NDP plots. In addition, pasture height (sward stick) was recorded daily at 10 cm intervals from 0 to 100 cm from pre-marked dung pats and from pegged point sources in NDP plots. The experiment lasted 10-11 days and mean pasture mass declined from 2850 to 1500 kg DM/ha. Grazing pressure was controlled by altering numbers of livestock to maintain < 250 kg DM/ha difference between each species plot. There was no difference in the mean pasture mass of the sheep or deer grazed plots at any stage of the experiment. However both species grazed pasture near pegs (NDP plots) to a lower mean height (P<0.001) than near dung pats although the difference was greater for deer (7.4 and 9.0 cm near pegs and near dung pats respectively) than sheep (8.0 and 8.3 cm near pegs and dung pats respectively). Sward height of pasture at 10-20 cm from dung pats grazed by deer was higher than sheep grazed pasture for days 1, and 3-7 of the trial (P<0.001). The results from this experiment indicate that although deer graze pasture around cattle dung pats, they show more of a preference for grazing further away from dung pats than do sheep. This finding should help to establish the potential for deer to substitute for sheep under mixed grazing situations involving cattle.

Sheep genomics - a trans-Tasman collaboration - Forage RG; Hynd PI (Proceedings of the New Zealand Society of Animal Production, 2006)
SheepGenomics is a major A$30 million initiative of Meat and Livestock Australia and Australian Wool Innovation Limited supported by 10 leading research organisations in Australia and New Zealand. It aims to discover genes that influence economically important traits in sheep. By using discoveries made within SheepGenomics’ research program, sheep producers will be able to start breeding for a wide range of economically important traits with greater confidence than is currently possible. One of the themes in the programme is to improve key aspects of wool quality and focus on genes that regulate follicle formation in the skin of foetal lambs. This paper describes key aspects of the management structure of SheepGenomics, an overview of three of the Subprograms (Muscle, Parasites and Coretech) and a more detailed description of the Wool Subprogram.

The sheep sustainability strategy : Project introduction and preliminary results - Bates J; Mirams G; Hickford J; Hill S (Proceedings of the New Zealand Society of Animal Production, 2006)
From the preliminary results in Table 2 a number of tentative conclusions can be drawn. It can be seen that a Levamisole drench is an effective option on many of the properties. A Combination (BZ & Lev) drench is effective on many properties also probably as a result of the Levamisole active efficacy. There is a high percentage of Ivermectin (Full dose) failure across the properties – one possible reason for this could be the high volume of Ivermectin used within the merino and mid micron sectors over recent years. It has been speculated that this high level of Ivermectin (full dose) usage was a result of early BZ drench failure (undiagnosed) in the mid micron and merino sectors.

A simple HPLC method for measuring sulfate in ultra filtered sheep plasma - Sinclair BR; Tavendale MH; Bermingham EN; Burke JL; McNabb WC; Roy NC (Proceedings of the New Zealand Society of Animal Production, 2006)
Plasma sulfate concentration is a useful indicator of sulfur amino acid oxidation. Measurement of sulfate in water and other fluids has been made by turbidimetric, ultra-violet (UV) absorption or ion chromatography HPLC methods. The turbidimetric method is variable and suffers from interferences and both turbidimetric and UV methods are less sensitive than ion chromatography. We describe a quick and simple HPLC method, where sample preparation is a centrifugal filtration and the sulfate measurement is by single column HPLC using one buffer at a constant flow rate. Recoveries from spiked samples were 99.5 % (RSD 1.8 %) and the RSD of repeated standards over 6 weeks was 0.7 %. Using this method, we measured plasma sulfate levels in both growing lambs with intestinal parasites and in sheep fed fresh Lotus corniculatus containing condensed tannins (CT) or other fresh forages. The CT in Lotus corniculatus decreased (P < 0.05) plasma sulfate concentration while parasite infection did not (P > 0.05). Our method provided quick and reliable data that could be transferable for measuring sulfate in blood, serum and other biological fluids and could be used as a biomarker of whole body sulfate status under various physiological conditions in farm animals.

Sources of dark fibre contamination in some lines of mid-micron fleece wools - Brief Communication - Reid TC; Urquhart RA (Proceedings of the New Zealand Society of Animal Production, 2006)
High-throughput technologies in the era of post-genomics provide new opportunities to investigate complex biological systems. Data can be collected for a system of interest at the level of gene expression, protein expression and metabolite concentration changes and then used for the assessment of interactions of molecules. However, the vast amount of information also poses challenges for data management, analysis, and interpretation. This paper aims to outline the technical complexity and the sources of variation in the technologies involved in molecular systems biology and computational strategies for data integration.

Stage of lactation affects the milking performance and behaviour of cows in a pasture-based automated milking system - Jago JG; Davis KL; Woolford MW (Proceedings of the New Zealand Society of Animal Production, 2006)
The successful implementation of automatic milking (AM) technology in pastoral dairy systems is dependent on the regular voluntary passage of cows from the grazing area to the dairy. A herd of 94 cows at the Dexcel Greenfield research farm was observed during a 31-day period to determine the effect of stage of lactation on milking performance and behaviour. Sixty-five cows were spring calved (late lactation, average 266 days in milk) and 29 were autumn calved (early lactation, average 19 days in milk). Cows were grazed as one herd in a rotational grazing management system with a fresh area of pasture available twice daily. Early lactation cows had a shorter average milking interval (14.6 vs 20.4 hours, p < 0.001) and a higher average daily production (20.0 vs 7.0 kg milk/cow/day, p < 0.001). They visited the selection units (from which they could gain access to water, fresh pasture and the raceway to the dairy housing the AM units) more often than cows late in lactation (2.8 vs 1.8 visits/cow/day, p < 0.001) and had a quicker transit time between pasture and the AM units (2.2 vs 2.7 hours/cow/milking, p = 0.026). Fewer early lactation cows needed to be manually moved from the grazing area for milking. The data indicates that stage of lactation will be a significant factor to consider when developing management systems for combining grazing with automatic milking.

A study of pelt and growth traits in Zandi sheep - Khojasteh KM; Emam Jome NK; Torshizy RV (Proceedings of the New Zealand Society of Animal Production, 2006)
The combination of metabolic profiling by a combination of broad-spectrum analytical methods and multivariate statistics offers new opportunities for obtaining a global over-view of metabolism. It also facilitates the discovery of metabolites which can serve as useful markers of biological processes or states (“biomarkers”). Fast liquid chromatography and electrospray ionisation mass spectrometry with collisioninduced dissociation in an ion-trap (fast LC-ESI-MS/MS) has been applied to determine metabolic profiles of bovine urine samples. The samples were collected twice daily from groups of five lactating dairy cows grazing in four different forage management systems comprising different spatial and temporal allocations of ryegrass (Lolium perenne) and white clover (Trifolium repens). The data have been analysed by different multivariate statistical methods, and a number of candidate biomarkers of forage feed and diurnal processes have been identified.

Supplemental fumarate did not influence milksolids or methane production from dairy cows fed high quality pasture - Kolver ES; Aspin PW (Proceedings of the New Zealand Society of Animal Production, 2006)
This experiment tested the hypothesis that methane emissions from dairy cows would be reduced, and milk production increased, when sodium fumarate was added to a diet of fresh pasture at a rate of 5% of dry matter (DM) intake. Sixteen ruminally fistulated dairy cows (100 ± 20.7 days in milk; 548 ± 47.8 kg liveweight; mean ± SD) received either a control (water) or fumarate treatment (10.3 ± 1.18 L/cow/day of solution providing 931 ± 126 g sodium fumarate/cow/day) over a 7-day adjustment period while grazing ryegrass pasture, followed by an 8-day experimental period fed pasture in metabolism stalls. During the experimental period cows on both treatments consumed 18.8 ± 1.83 kg DM/day, produced 1.81 ± 0.25 kg milksolids/day, and emitted 350 ± 44.9 g methane/day (5.9 ± 0.71% of gross energy). Total tract DM digestibility was high (78.8 ± 0.84%), and ruminal pH was 6.10 ± 0.15. Fumarate supplementation did not change ruminal fermentation, in vivo digestibility, methane emissions, milk production or composition, or selected plasma metabolites. The opportunity for reducing methane emissions from dairy cows by supplementing with fumarate or breeding high fumarate grasses may be limited for diets of high quality pasture. The limited reports of in vivo response to supplemental fumarate suggest that mitigation opportunities may be greater for pasture diets of low digestibility.

Supplementation with concentrates either pre- or post-partum does not affect milk production when diets are iso-energetic - Roche JR; Lee JM; Aspin PW; Sheahan AJ; Burke CR; Kolver ES; Sugar B; Napper AR (Proceedings of the New Zealand Society of Animal Production, 2006)
Dairy cow glucose requirements increase dramatically during the weeks preceding calving, suggesting that supplements that increase glucose supply (rapidly fermentable carbohydrates) would reduce precalving mobilisation of body tissue and improve subsequent milk production. Sixty-eight multiparous dairy cows were randomly allocated to one of two diets for 36 ± 8.7 days precalving. All cows were fed pasture and pasture-silage precalving, with one group also receiving 3kg DM of a barley-maize concentrate. Precalving diets were iso-energetic (114 MJ/cow/day). At calving, cows within each precalving feeding treatments were randomly allocated to two dietary treatments for 35 days in a 2x2 factorial arrangement. Postcalving, all cows received pasture and pasture silage with one group also receiving 5.0 kg DM of a barley-maize concentrate. Postcalving diets were also iso-energetic (179 MJ/cow/day). Milk yield and composition, and liveweight (LW) and body condition score (BCS) were assessed weekly for five weeks. Blood was sampled on day -21, -14, -7, 0, 1, 2, 3, 4, 7, 14, 21, 28 and 35 relative to calving, and plasma samples were analysed for indicators of energy status. Average milksolids yield (1.9 kg/cow/d) during the five weeks postcalving was not affected by either pre- or postcalving concentrate supplementation, although protein to fat ratio was higher in supplemented cows. Similarly, concentrate supplementation pre- or postcalving did not affect either LW or BCS change before or after calving. Cows receiving concentrates precalving had higher (P<0.001) plasma non-esterified fatty acid (NEFA) concentrations, but otherwise were not different to those receiving an equivalent energy intake from pasture and pasture silage. Postcalving concentrate supplementation increased (P<0.01) plasma glucose and NEFA and decreased (P<0.001) plasma B-OH butyrate. Results suggests little effect on milk production by replacing energy from structural carbohydrates in high quality pasture with energy from non-structural carbohydrate during the transition period.

Supplementing dairy cows with oils to improve performance and reduce methane ? does it work? - Woodward SL; Waghorn GC; Thomson NA (Proceedings of the New Zealand Society of Animal Production, 2006)
Oil supplements can be used in dairy rations to increase dietary energy density (and energy intake) and reduce methane (CH4) emissions from rumen fermentation. Trials at Dexcel measured effects of oil supplementation on dry matter intake (DMI), milk yield and methane production after lactating dairy cows were fed pasture-based diets for short (14-day) and long (12-week) periods. In the short-term trial, 32 cows received either no oil or three mixtures of sunflower and fish oil at 500g/d. In the long-term trial 20 cows grazed pasture and received either no oil or 300g linseed and fish oil for 11 weeks prior to methane measurements. The type of oil in the short-term trial did not affect methane production and oils had no effect on DMI or milk yield but reduced total methane emissions by 27% (176 vs. 242g CH4/cow/d, sed=10.6) and CH4/kg DM (13.5 vs. 18.5g CH4/kg DM, sed=0.88). In the long-term trial, oil had no effect on methane emissions (353 (oil) vs. 323g CH4/cow/d (control), sed=17.0 and 21.7 vs. 23.0g CH4/kg DM, sed=1.01). These trials did not show benefits of oils for milk production and emphasize the need for longterm studies when developing on-farm strategies for methane mitigation.

Supplementing mature cows with either cereal or lipid-based supplements had no effect on the post-partum anoestrous interval - Meier S; Gore P; Minnee E; Thomson N (Proceedings of the New Zealand Society of Animal Production, 2006)
A large scale retrospective study was undertaken in2005 on the impact of the policies for induction of early calving (either undertaken during study period, stopped in previous 2 seasons, or continuing to induce) and other factors on herd reproductive performance. Data was gathered from whole-herd pregnancy testing data and farm visit records, and electronic records from the LIC database. Data analysed included records from 3 consecutive seasons from 82 herds, and included 34,729 cows, 72,593 calvings, 237,884 individual herd test records and summary pregnancy test results for each herd for 3 seasons. Factors that significantly influenced herd reproductive performance were herd induction policy, season, herd predominant breed, 4 week submission rate, average milk protein percent at herd test within 60 days following the start of the breeding programme, and length of breeding programme (all P< 0.01). Induction usage was found to be declining over time, implemented at a later stage of the calving programme and unlikely to meet Code of Practice requirements, and under-reported to the LIC database. This large-scale epidemiologic study provides important information for herd owners, their advisors, and other scientists on herd reproductive performance.

Systems biology and metabolomics : Experimental and computational challenges - Cao M; Koulman A; Pacheco D; Lane GA; Rasmussen S (Proceedings of the New Zealand Society of Animal Production, 2006)
High-throughput technologies in the era of post-genomics provide new opportunities to investigate complex biological systems. Data can be collected for a system of interest at the level of gene expression, protein expression and metabolite concentration changes and then used for the assessment of interactions of molecules. However, the vast amount of information also poses challenges for data management, analysis, and interpretation. This paper aims to outline the technical complexity and the sources of variation in the technologies involved in molecular systems biology and computational strategies for data integration.

Teat spraying prior to calving may reduce the risk of heifer mastitis caused by Streptococcus uberis - Lopez-Benavides MG; Williamson JH; Lacy-Hulbert SJ; Cursons RT (Proceedings of the New Zealand Society of Animal Production, 2006)
Heifer mastitis caused by Streptococcus uberis is a significant problem for New Zealand dairy farmers. The mechanisms of infection in the pre-partum period have not been fully elucidated but prior research has established that the teats of dairy cows are contaminated with significantly higher numbers of S. uberis during the dry period as compared to during lactation. It is hypothesised that gross teat-end contamination by these bacteria before calving is a significant risk factor for the entry of bacteria through the teat canal and establishment of infection. Regular disinfection of the teats in the dry period was evaluated as a means to reduce teat-end contamination and consequently to decrease the likelihood of glands developing an infection. Two groups of 27 heifers were assigned to either a ‘sprayed’ or ‘not-sprayed’ treatment. The sprayed heifers were teat-sprayed with a commercial iodine-based post-milking teat sanitizer three times a week for the last three weeks before calving. Before commencement of the experiment, teat-ends were swabbed to determine pre-existing contamination with S. uberis, which averaged 610 colony-forming units (cfu). Prior to calving, S. uberis counts on teat-ends were 560 cfu for the sprayed group and 1775 cfu for the non-sprayed group (p = 0.06). Bacteriology of milk from each gland at the first milking showed that 4% of glands of the sprayed heifers were infected with S. uberis compared with 11% for the non-sprayed heifers (p < 0.05). At the first herd test, heifers in the sprayed group had a lower SCC (380,000 cells/ml) compared to the non-sprayed group (790,000 cells/ml), although due to the small size of the study, this difference was not significant. It was concluded that teat-spraying in the dry period could reduce teat-end contamination and consequently the proportion of glands infected by S. uberis at calving.

To induce or not to induce? Insights into important influences on dairy farmer decision making over induced calving - Blackett P; Compton CWR; Glassey C (Proceedings of the New Zealand Society of Animal Production, 2006)
Between 1998 and 2004 a sire progeny test was run atthe Poukawa Research Farm in Hawke’s Bay. Four ewe genotypes were used (Romney, East Friesian x Romney, Finn x Romney and Poll Dorset x Romney) with up to 900 ewes mated each year. Datawas collected on 4614 lambs born to 74 rams (an average of 62 progeny per ram). Rams used represented 13 different terminal sire and dual purpose breeds. Ewes were mated using AI or single-sire mated in the paddock for one cycle. Lambs were tagged and weighed within 24 hours of birth. At 12 weeks ofage, lambs were weighed and scanned for eye muscle dimensions from which eye muscle area was estimated. Data were analysed using a REML animal model taking account of repeat matings among parents, genetic relationships among animals and incorporating adjustments for fixed effects associated with year, ewe genotype and litter size. At a mean lambing percentage of 165%, the mean birth weight across all sires was 4.91 kg and ranged between 4.21 and 5.46 kg for individual sires. The mean 12 week liveweightwas 29.8 kg and ranged from 26.5 to 33.1 kg for progeny from individual rams. There was a wide range in GR fat depth (mean 8.9 mm, sire range 6.9 to 12.3 mm) when corrected to a constant carcass weight of 18.3 kg. The top rams for liveweight were not necessarily top for other characteristics. Significant numbers of lambs are sold store at weaning on a liveweight basis and this makes it possible to place a value on pre-weaning growth. At $2/kgliveweight, the average lamb sired by the top ram for growth would be worth $66.20 and the progeny from the bottom ranked sire would be worth $53 - a difference of $13.20 per lamb. Assuming these rams had an active lifespan of 4 years and mated 80 ewes rearing 125% per year, each ram would leave 400 progeny. At $13.20 per lamb the difference in value between the top and bottom ranked rams would be $5280. These results show the differences between rams and highlight the importance of using breeding values in the ram selection process.

Urinary biomarkers of forage feeding from ESI-MS/MS fingerprinting: exploratory studies - Lane GA; Fraser K; Cao M; Koulman A; Cosgrove GP; Death A (Proceedings of the New Zealand Society of Animal Production, 2006)
The combination of metabolic profiling by a combination of broad-spectrum analytical methods and multivariate statistics offers new opportunities for obtaining a global over-view of metabolism. It also facilitates the discovery of metabolites which can serve as useful markers of biological processes or states ("biomarkers"). Fast liquid chromatography and electrospray ionisation mass spectrometry with collision-induced dissociation in an ion-trap (fast LC-ESI-MS/MS) has been applied to determine metabolic profiles of bovine urine samples. The samples were collected twice daily from groups of five lactating dairy cows grazing in four different forage management systems comprising different spatial and temporal allocations of ryegrass (Lolium perenne) and white clover (Trifolium repens). The data have been analysed by different multivariate statistical methods, and a number of candidate biomarkers of forage feed and diurnal processes have been identified.

The use of alternative therapies in racing thoroughbreds - Coleman HJ; Rogers CW; Gee EK (Proceedings of the New Zealand Society of Animal Production, 2006)
The use of alternative therapies (physiotherapy, chiropractic, etc) in the New Zealand (NZ) Thoroughbred appears to be common practice, despite the lack of scientific evidence to support their use in the species. It is unknown what treatments are being offered to these athletes, the types of problems alternative therapies are used for, if the ‘therapists’ providing the treatments are qualified, and if the horses seen by therapists are also under veterinary care. To obtain preliminary data on the use of alternative therapies in the NZ Thoroughbred horse a face to face survey was conducted with 23 trainers located in the Auckland and Manawatu regions of the North Island of NZ. The data collected represented 906 racehorses in training during the 2004/2005 racing season. Stables were categorized as small (less than 10 horses, n=8), medium (11-25 horses, n=8) and large (greater than 26 horses in training, n=7). The proportion of horses injured within each stable category was 21%, 28% and 33% respectively. Nineteen trainers out of the 23 surveyed used at least one type of alternative therapy during the racing season, and 296 horses (33%) had at least one exposure to alternative therapy. On average trainers spent $25,026 per year on veterinary treatments and $43,112 on alternative therapies. Eleven different types of alternative therapy were identified by trainers, with physiotherapy being the most commonly used (10 trainers), particularly by large (71%) and small (63%) stables. Eight stables used some form of alternative therapy on a monthly basis to treat 33% of their horses in training, 4 on a weekly basis to treat 47% of their horses and 3 on a daily basis to treat 44% of their horses. Sixteen different alternative therapists were identified in this study, 7 had formal qualifications. The data collected indicated that the use of alternative therapies in the NZ Thoroughbred industry was widespread.

Using a whole farm model to explore options for feed grown on-farm to achieve 1750 kg milksolids per hectare in the Waikato - Beukes PC; Clark CEF; Wastney ME; Palliser CC; Levy G; Folkers C; Lancaster JAS; Leydon-Davis C; Thorrold BS (Proceedings of the New Zealand Society of Animal Production, 2006)
Dexcel`s Whole Farm Model (WFM) is a computer model of a dairy farm that simulates individual cows and paddocks, with pasture growth driven by observed climate data and with management policies guiding decisions on a daily basis. The aim of the study was to design a farm system to produce 1750 kg milksolids (MS)/ha/yr from feed grown on-farm. An average predicted pasture growth curve was derived by initialising the WFM for a typical all-pasture Waikato farm (3 cows/ha) with "best practice" management policies and running the simulation for 29 years of Ruakura climate data. The model was then used with this average growth curve to design the high producing system. Pasture growth alone (17.3 t DM/ha) did not fulfil the feed requirement for the 1750 kg MS/ha scenario, with an overall feed deficit of 3.1 t DM pasture/ha. Improvements in ryegrass cultivars and N-fertilisers could be expected to increase pasture production by around 10%, reducing the overall feed deficit to 1.6 t DM pasture/ha. These improvements together with irrigation at 2 mm/day over the three summer months (Dec - Feb) reduced the feed deficit to zero. Irrigation could be replaced by cropping between 11% and 20% of the farm in a rotation of annual ryegrass yielding 7 t DM/ha and maize yielding 22 to 28 t DM/ha respectively.

Variation in the New Zealand ram breeding industry ? results from the Poukawa progeny test - Muir PD; Thomson BC; Smith NB; Clarke JN (Proceedings of the New Zealand Society of Animal Production, 2006)
Between 1998 and 2004 a sire progeny test was run at the Poukawa Research Farm in Hawke’s Bay. Four ewe genotypes were used (Romney, East Friesian x Romney, Finn x Romney and Poll Dorset x Romney) with up to 900 ewes mated each year. Data was collected on 4614 lambs born to 74 rams (an average of 62 progeny per ram). Rams used represented 13 different terminal sire and dual purpose breeds. Ewes were mated using AI or single-sire mated in the paddock for one cycle. Lambs were tagged and weighed within 24 hours of birth. At 12 weeks of age, lambs were weighed and scanned for eye muscle dimensions from which eye muscle area was estimated. Data were analysed using a REML animal model taking account of repeat matings among parents, genetic relationships among animals and incorporating adjustments for fixed effects associated with year, ewe genotype and litter size. At a mean lambing percentage of 165%, the mean birth weight across all sires was 4.91 kg and ranged between 4.21 and 5.46 kg for individual sires. The mean 12 week liveweight was 29.8 kg and ranged from 26.5 to 33.1 kg for progeny from individual rams. There was a wide range in GR fat depth (mean 8.9 mm, sire range 6.9 to 12.3 mm) when corrected to a constant carcass weight of 18.3 kg. The top rams for liveweight were not necessarily top for other characteristics. Significant numbers of lambs are sold store at weaning on a liveweight basis and this makes it possible to place a value on pre-weaning growth. At $2/kg liveweight, the average lamb sired by the top ram for growth would be worth $66.20 and the progeny from the bottom ranked sire would be worth $53 - a difference of $13.20 per lamb. Assuming these rams had an active lifespan of 4 years and mated 80 ewes rearing 125% per year, each ram would leave 400 progeny. At $13.20 per lamb the difference in value between the top and bottom ranked rams would be $5280. These results show the differences between rams and highlight the importance of using breeding values in the ram selection process.

Variation in the New Zealand ram breeding industry û results from the Poukawa progeny test - Muir PD; Thomson BC; Smith NB; Clarke JN (Proceedings of the New Zealand Society of Animal Production, 2006)
Between 1998 and 2004 a sire progeny test was run at the Poukawa Research Farm in Hawke’s Bay. Four ewe genotypes were used (Romney, East Friesian x Romney, Finn x Romney and Poll Dorset x Romney) with up to 900 ewes mated each year. Data was collected on 4614 lambs born to 74 rams (an average of 62 progeny per ram). Rams used represented 13 different terminal sire and dual purpose breeds. Ewes were mated using AI or single-sire mated in the paddock for one cycle. Lambs were tagged and weighed within 24 hours of birth. At 12 weeks of age, lambs were weighed and scanned for eye muscle dimensions from which eye muscle area was estimated. Data were analysed using a REML animal model taking account of repeat matings among parents, genetic relationships among animals and incorporating adjustments for fixed effects associated with year, ewe genotype and litter size. At a mean lambing percentage of 165%, the mean birth weight across all sires was 4.91 kg and ranged between 4.21 and 5.46 kg for individual sires. The mean 12 week liveweight was 29.8 kg and ranged from 26.5 to 33.1 kg for progeny from individual rams. There was a wide range in GR fat depth (mean 8.9 mm, sire range 6.9 to 12.3 mm) when corrected to a constant carcass weight of 18.3 kg. The top rams for liveweight were not necessarily top for other characteristics. Significant numbers of lambs are sold store at weaning on a liveweight basis and this makes it possible to place a value on pre-weaning growth. At $2/kg liveweight, the average lamb sired by the top ram for growth would be worth $66.20 and the progeny from the bottom ranked sire would be worth $53 - a difference of $13.20 per lamb. Assuming these rams had an active lifespan of 4 years and mated 80 ewes rearing 125% per year, each ram would leave 400 progeny. At $13.20 per lamb the difference in value between the top and bottom ranked rams would be $5280. These results show the differences between rams and highlight the importance of using breeding values in the ram selection process.

Variation in yields of milk and milk solids in Holstein cows induced to calve prematurely - Jaques SA; Macmillan KL; Anderson GA; Morton JM (Proceedings of the New Zealand Society of Animal Production, 2006)
Milk production was compared between multiparous Holstein cows that were induced to calve and herdmates that calved spontaneously at approximately the same time in 88 dairy herds from Victoria and Tasmania. Yield averages for each herd were calculated for induced and spontaneously calving cows for milk volume, milkfat and protein during the first 120 days of lactation and for 305 days. Associations between induced and spontaneously calving groups for 305-day yields were described using linear equations. Slopes ranged from 0.82 (for milk yield) to 0.87 (for protein yield) and R2 values ranged from 0.84 to 0.88 (P<0.001). The average reduction in milk yield over the 88 herds was 366 litres (7%). The estimated milk yield reduction for induced groups in herds where spontaneously calving contemporaries averaged only 3500 litres per 305 days was 40 litres (1.1%) compared to an average estimated reduction of 915 litres (11%) in herds averaging 8500 litres. Similar proportional reductions were calculated for 305-day yields of milkfat and protein. Collectively these results show that yield reductions following induced premature parturition are substantially higher in absolute as well as proportional terms in herds with higher milk yields.

Whole-body protein turnover in Merino sheep selected for wool and body growth - Li L; Oddy VH; Godwin I; Hegarty J; Nolan JV (Proceedings of the New Zealand Society of Animal Production, 2006)
The objective of this research was to identify metabolites produced by commensal bacteria that enhance the integrity of the gastrointestinal barrier (GIB). The integrity of the GIB is mainly determined by the complexity of interactions between tight junctions of opposing epithelial cells of the GI wall. This was measured using an in vitrobioassay, consisting of a monolayer of intestinal epithelial cells grown on a membrane. The trans-epithelial electrical resistance (TEER) across this monolayer was measured to determine the strength of the tight junctions. Preliminary results showed that a commercial probiotic product caused an increase in TEER across non-differentiated and differentiated monolayers by 178 ± 61% and 40 ± 9%, respectively. The maximum increases in TEER obtained with conditioned media fractions (media fractions containing components secreted by the probioticproduct) was between 23 ± 6% and 43 ± 4%. The conditioned media fraction containing components less than 3 kDa accounted for the total activity of the whole conditioned media. Metabolite profiling ofactive conditioned media compared to inactive conditioned media using fast-LCMSMS identified numerousmetabolites that may be responsible for this positive effect. Future work will isolate the candidate metabolites and screen them for GIB enhancing activity both in vitroand in vivo.

Wool keratins - the challenge ahead - Plowman JE; Bryson WG; Yu Z-D; Gordon SW; Pearson AJ; Kelly RJ (Proceedings of the New Zealand Society of Animal Production, 2006)
Sheep wool is predominantly composed of keratin proteins. These comprise keratin intermediate filament proteins embedded in a matrix of smaller keratin associated proteins. As a result of polymorphisms and post-translational modifications, these proteins display many more family members than there are genes. Recent studies using improved gene expression, electron tomography and proteomic techniques have provided useful preliminary data on the association of keratins with certain fibre properties. Current research is quantifying keratin gene expression in the skin and the consequent wool protein compositional differences between breeds of divergent fibre and fleece characteristics. A detailed understanding of the control of keratin gene expression and fibre protein composition arising from these and other studies will provide the foundation for the development of novel high-value wool types, solubilised keratins for specialised cosmetic applications and reconstituted keratin polymers for biomedical applications.

The AgriBaseÖ farm location database - Sanson RL (Proceedings of the New Zealand Society of Animal Production, 2005)
AgriBase™ is a national spatial farms database. It was launched in 1993 and now holds information on approximately 105,000 live (current) farms. Each distinct farm has a unique farm identifier - the Farm_ID. AgriBase holds key contact details for the farm, predominant farm type, overall size, animal numbers by stock class, planted areas for different orchard or crop types (including forestry), and the spatial coordinates of the farm usable within a geographic information system. Both government and private sector groups use AgriBase™ as a master index for all rural land holdings involved in some form of primary production. It has been used in exotic disease and pest investigations and responses, rescue helicopter missions, epidemiological research into human and animal health issues, development of environmental indicators, within-farm fertiliser planning, among others. AgriBase™ was extensively used during the February 2004 floods in the lower North Island to locate and contact affected farmers and survey the levels of damage. It is proposed that AgriBase™ has a central role to play in the development and delivery of food safety traceability and verification systems for New Zealand. Key Words: farm; database; Geographic Information System (GIS); food safety; traceability.

Animal welfare in large dairy herds: a survey of current practices - Tucker CB; Verkerk GA; Small BH; Tarbotton IS; Webster JR (Proceedings of the New Zealand Society of Animal Production, 2005)
To gain insight into the farm practices and animal welfare issues on large dairy herds, we conducted a postal survey (n = 132). The questionnaire covered four areas: demographics, stand-off practices, management during extreme weather, and races. Respondents managed 910 ± 466 (mean ± SD) milking cows during the 2003 season. When asked to identify the most important animal welfare problem on their farm, 73% of the respondents named one of the following: lameness, disease, or nutrition/growth. Fifty-one percent of respondents used some form of stand-off area during periods of inclement weather. There are several management practices used with stand-off areas that are relevant to animal welfare including: provision of feed, shelter, space allowance, and surface type. During extreme winter and summer weather, a range of practices was used to manage cows, including changes in grazing patterns. For example, 61% of respondents used paddocks closer to the milking shed and 40% used sprinklers at the shed during hot weather. Finally, on average, cows walked 1.9 ± 0.8 km to the milking shed, and walking distance increased with the number of cows/farm. Farmers demonstrated awareness of animal welfare issues and implemented management practices that likely improve the well-being of their stock. KEYWORDS: animal welfare; dairy cattle; herd size; management practices.

Applying traceability across an industry - Purcell C (Proceedings of the New Zealand Society of Animal Production, 2005)
Livestock Improvement Corporation (LIC) has a world leading capability in individual animal recording of which MINDA is the product that is most often associated with traceability. MINDA annually handles many millions of transactions that relate to individual animals, herds, farms, and the people who are associated with them. Currently, it is primarily a dairy application but other species are represented. MINDA already captures data that are required for traceability (lifetime ID, birth, death, movements, health records) on a central database, and does so using a variety of tools that suit all customer profiles. LIC systems include a trace forward/back functionality, integrated with existing internal GIS systems.

Associations between Streptococcus uberis populations on farm races and climatic changes during a twelve-month period - Lopez-Benavides MG; Williamson JH; Cursons RT (Proceedings of the New Zealand Society of Animal Production, 2005)
Streptococcus uberis is an important mastitis-causing pathogen in cows managed under pastoral conditions. The influence of environmental conditions on S. uberis ecology in dairy farms is unknown. To evaluate associations between climatic parameters and population levels of the bacterium on the farm, farm races were monitored for S. uberis levels on a fortnightly basis from November 2003 to November 2004 at the Dexcel Lye research farm. Higher S. uberis contamination was observed in races where cow traffic was frequent and lower in areas where usage was minimal. Highest S. uberis contamination occurred in the month of August (630 cfu/g) and lowest in January (2 cfu/g). Significant associations were observed between S. uberis levels and relative humidity (r = 0.6), soil temperature at a depth of 10 cm (r = -0.8), solar radiation (r = -0.7) and maximum air temperature (r = -0.7). Around 70% of S. uberis clinical mastitis cases occurred in the non-lactating and calving periods, when S. uberis levels in races were above 100 cfu/g and solar radiation levels were low. It is suggested that weather conditions have a significant impact on the survival of S. uberis in the dairy farm environment.

Comparing feed allowances to inferred energy intake using data from a dairy grazing farm trial - Pryce JE; Harris BL; Montgomerie WA; Jackson R; MacDonald KA; Glassey CB; Thorrold BS; Holmes CW (Proceedings of the New Zealand Society of Animal Production, 2005)
The main objective of this research was to investigate whether calculating intake of dairy cows using equations to predict energy requirements provides a good alternative to conventional ways of estimating intake. The method was applied to data from the Dexcel Holstein-Friesian strain trial over three seasons. Feed intake per cow was calculated as the sum of the energy requirements for maintenance, milk production, pregnancy, growth and body tissue mobilisation using measured yields of milk, fat, protein and lactose, live weight and body condition score of cows and calf live weights. In order to compare the estimates of feed intake to the amount of feed offered, linear regressions of calculated (ME) intake (grouped by farmlet) on the amount ME offered per farmlet were performed by season. The relationship between ME intake and ME offered was weak in the first year, with a limited response to increasing the amount of feed offered. This was because all the cows were two-year-olds with lower live weights and milk yields and consequently lower feed intakes. In the subsequent two years of the trial, the relationship between ME intake calculated using the energy equations were 67% and 72%. The modern strains of dairy cows responded well to higher levels of feed offered, while the 1970s strain of New Zealand dairy cows failed to increase intake when offered diets of higher total ME. Our results show that energy prediction equations offer a viable and cheap alternative of estimating ME intake of lactating dairy cows. KEYWORDS: dairy cows; energy intake; strain comparison; efficiency.

Condensed tannins in birdsfoot trefoil (Lotus corniculatus) affect the detailed composition of milk from dairy cows - Turner S-A; Waghorn GC; Woodward SL; Thomson NA (Proceedings of the New Zealand Society of Animal Production, 2005)
Feeding birdsfoot trefoil (lotus, Lotus corniculatus) to dairy cows increases milk solids production and reduces methane production relative to ryegrass pasture. This study has measured the affect of lotus and lotus condensed tannins (CT) on milk protein and lipid composition. The trial involved 32 Friesian dairy cows offered either good quality perennial ryegrass pasture or lotus. Half of the cows given each diet were drenched with polyethylene glycol (PEG) to inactivate the CT. A daily milk sample was collected from all cows prior to and towards the end of the treatment period. Gross milk fat and milk protein concentrations were similar for cows fed lotus or ryegrass. Neither feed, nor CT affected individual proteins in the milk with the exception of lactoferrin (Lf) where the CT in lotus increased concentrations (138 vs 76 mg/l; P < 0.01). Forage type affected the composition of fatty acids (FA) in the milk with cows gazing lotus having higher concentrations of de novo synthesised (C4:0-C15:0; 28.3% vs 26.7%; P < 0.01) and lower concentrations of pre-formed (C17:0 and longer; 34.5% vs 39.0%; P < 0.05) FA than those grazing ryegrass. The CT in lotus appeared to affect ruminal biohydrogenation of FA, decreasing the concentration of saturated FA in the milk fat, and increasing in the concentrations of the omega-3 FA (1.5% vs 1.1%; P < 0.01). Changes in the saturation and proportions of FA may affect processing characteristics and functionality of milk from cows fed lotus. CT in lotus may also provide potential new avenues for increasing milk value on-farm. KEYWORDS: detailed milk composition; Lotus corniculatus; condensed tannins.

Corticosteroid treatment prevents the reduction in food intake and growth in lambs infected with the abomasal parasite Teladorsagia circumcincta - Greer AW; McAnulty RW; Stankiewicz M; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 2005)
Recent studies with Trichostrongylus colubriformis have provided some direct evidence to support the view that the major contributor to reduced production in gastrointestinal nematode infections is the host immune response, rather than damage from the parasite per se. However, it is unknown if this is also true for abomasal infections. Parasite naïve lambs were either trickle infected with Teladorsagia circumcincta L3 larvae; similarly infected and concurrently immuno-suppressed with the corticosteroid methylprednisolone acetate; immuno-suppressed only; or remained as controls. Immuno-suppression abrogated the reduction in intake and subsequent production losses and reduction in feed conversion efficiency associated with infection suggesting the damage caused by this abomasal parasite per se may have little detrimental effect on lamb productivity. These findings add weight to the view that components of the developing immune response are generally the cause of reduced productivity in infected lambs. They may have ramifications for the genetic selection of animals that are predisposed to mount a strong immune response. KEYWORDS: immuno-suppression; nematodes; intake; feed conversion efficiency; sheep.

The cost of alleviating the pain caused by the castration of beef calves - Stafford KJ; Mellor DJ; Dooley AE; Smeaton D; McDermott A (Proceedings of the New Zealand Society of Animal Production, 2005)
The pain caused by husbandry procedures such as dehorning or castration is of concern to those with an interest in animal welfare. In the future farmers will be encouraged and perhaps obliged to provide analgesia for animals subjected to these procedures. In New Zealand in the last decade veterinarians have developed a service for disbudding dairy calves using the sedative xylazine and local anaesthesia and this has become popular with some dairy farmers. This paper reports a financial analysis of the impact to the individual farmer and nationally of using different forms of analgesia when castrating calves. Four scenarios and their costs were analysed: (1) the status quo ($0.28/calf); (2) the use of local anaesthesia with increased labour costs ($1.56/calf); (3) the use of local anaesthesia plus systemic analgesia with increased labour costs ($5.45/calf); and (4) the employment of a veterinarian to do the castration ($9.39/calf). National costs ranged from $160,000 to $5,368,700 ($10 to $351 per farm) for the four scenarios. The proposed scenarios were more expensive than the status quo but were still small relative to average total farm costs, i.e. $170,974 on New Zealand sheep and beef farms in 2001-02. These figures do not include any allowance for the cost of the inconvenience of having to organise husbandry activities around veterinary visits. Farmers may resist the imposition any of these 3 scenarios. In future the use of analgesics may become standard farm practice.

Development of an experimental approach to measure vitamin B12 production and utilisation in sheep - Ludemann MR; Sedcole JR; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 2005)
Cobalt (Co) is required by ruminants to enable synthesis of vitamin B12 by rumen micro-organisms. Lack of quantitative information on the synthesis, absorption or utilisation of the vitamin has made determining nutrient requirement difficult. Two trials with sheep previously depleted of vitamin B12 and offered low Co diet (0.08 mg/kg DM) are described which attempt to overcome these problems. In the first, ewes were dosed with Co intra-ruminally at rates between 0–1 mg Co/day. Responses in plasma vitamin B12 were proportional (P < 0.001) to the amount of Co infused. In the second trial, vitamin B12 was infused into the bloodstream via the jugular vein at rates between 0–2500 nmol/day. Plasma vitamin B B12 plateau values were directly proportional (P < 0.001) to infusion rate. The rate of vitamin B12 infusion needed to sustain the critical plasma concentration of 370 pmol B12 /l was 5.02 nmol B12 /day, which together with estimated absorption from the basal diet gives a total requirement for absorption of 8.12 nmol B12 /day. This value is in agreement with data in the literature. The model approach, therefore, seems quantitatively robust. This approach, together with estimates of vitamin B12 flow from the rumen, will enable study of dietary factors that predispose to poor vitamin B12 production in the rumen and its absorption from the alimentary tract, and therefore to low animal vitamin B12 status. KEYWORDS: Co/vitamin B12; infusion; sheep; rumen; modelling.

Differences in grazing behaviour and herbage intake between genotypes of Holstein-Friesian dairy cows grazing short or long swards - Rossi JL; MacDonald KA; Thorrold BS; Hodgson J; Holmes CW (Proceedings of the New Zealand Society of Animal Production, 2005)
The objective of this work was to compare dry matter intake and grazing behaviour of different strains (S) of Holstein-Friesian dairy cows during early lactation. Three strains of different origin [two 1990’s genotypes of Holstein- Friesian from Overseas (OS90) or New Zealand (NZ90) origin and a 1970’s NZ Friesian (NZ70)] were offered low or high pre-grazing herbage mass (HM) (2100 vs 2800 kg DM/ha) at a common daily allowance (35 kg DM/cow) between September and November 2004. Pasture dry matter intake (IT) and digestibility (D) were determined using the n-alkanes methodology. Time spent grazing (GT) and ruminating (RT) were observed for 24 hours. Intake per empty body live weight unit (ILW) and rate of intake (IRATE) were calculated. There was a significant SxHM interaction (P < 0.001) for IT and ILW. IT was similar at low HM across strains, whereas at high HM, a lower IT was recorded for the NZ70 while it was higher for the OS90. At low HM, ILW was slighter lower in the OS90 than in the NZ90 (P = 0.06) while at high HM both NZ90 and OS90 showed a higher ILW. In vivo digestibility was similar across strains but was higher at high HM (P < 0.001). There was a significant SxHM interaction for GT (P < 0.01) with both NZ strains spending more time grazing at low HM, in contrast, GT was similar across strains at high HM. RT was higher for the OS90 strain than for both NZ strains (P < 0.05) and greater at high HM (P < 0.001). There was a significant SxHM interaction for IRATE (P < 0.05) with the NZ90 and OS90 strains showing similar IRATE at low HM but different at high HM. Results indicate a difference in the ability of the strains to adjust their grazing behaviour to different pre-grazing herbage mass. KEYWORDS: Holstein-Friesian; high-merit dairy cow; intake; grazing behaviour, herbage mass.

Digestion kinetics of New Zealand native flax - Litherland AJ; Layton DL; Burke JL; Corson DC; Peters JS (Proceedings of the New Zealand Society of Animal Production, 2005)
This experiment compares the nutritive value of New Zealand native flax, Phormium tenax, by-products i.e. leaves (L), butts (B), thrash-stripped fibre (F) and green matter (G), with white clover (WC) via digestion kinetics derived from in vitro and in sacco incubations. The WC had a high nutritive quality (11.1 MJME/kg DM, CP 28% DM), G a moderate (10.1 MJME/kg DM, CP 9% DM), and L, B, F were of very low nutritive quality (< 8 MJME/kg DM, CP < 6 % DM). After 24 hours, 96, 76, 47, 47, and 30 % of the DM was degraded for WC, G, L, B and F, respectively (P < 0.001). The degradation rates (%/h) of digestible DM were faster (P < 0.001) for WC (13) and G (11) than B (3.8), L (4.6) and F (2.7). Flax by-products had a net loss of ammonia after 2 (B), 4 (F and L) and 8 hours (G). The proportion of DM converted to VFA by 8 hours was 21 %, and 14 % for WC and G respectively, but only 9-10 % for the other flax by-products (P < 0.001). The feeding model BestFeed™ predicted that G could grow a 500 kg bull at 0.8 kg/day and had potential as a supplement for pasture-fed animals. KEYWORDS: flax; Phormium tenax; in sacco; in vitro; digestion kinetics; nutritive value; forage ration, BestFeed.

Does ewe nutrition during pregnancy affect the metabolism of twin-born lambs? - Corner RA; Kenyon PR; Stafford KJ; West DM; Oliver MH; Morris ST; Blair HT (Proceedings of the New Zealand Society of Animal Production, 2005)
An insulin tolerance test was conducted on twin-born ewes born to dams offered sward heights of either 2 or 6 cm between day 64 and 132 of pregnancy in order to identify any alterations in the lamb’s metabolism. Lambs were also categorised into groups according to birth weight (< 4.0 kg, light and > 4.0 kg, heavy). Changes in metabolism may have long term effects on growth and productivity. An insulin challenge (0.2 U/kg) was administered to ewe lambs at 8 months of age and their plasma insulin, glucose and cortisol responses were monitored. The plasma cortisol concentration of ewe lambs born to ewes offered 2cm sward height was significantly (P < 0.05) higher than ewe lambs born to ewes offered 6 cm sward height 50 minutes after the insulin challenge. No difference was found in the insulin or glucose response to the insulin challenge between dam sward height group (2 vs 6 cm). Birth weight had no effect on the insulin, glucose or cortisol response of the ewe lambs to the insulin challenge. These results show that both dam nutrition and lamb birth weight had little to no effect on the metabolic responses measured. These results suggest that lambs born to ewes offered a herbage sward height of only 2 cm or lambs with low birth weights may not show altered metabolism. KEYWORDS: lamb; insulin tolerance test; twins; ewe nutrition; metabolism.

Does the ewe nutrition during pregnancy affect the behaviour of ewe lambs at 1 and 2 years of age? - Corner RA; Kenyon PR; Stafford KJ; West DM; Morris ST; Blair HT (Proceedings of the New Zealand Society of Animal Production, 2005)
The effects of the dam’s nutrition during pregnancy on her lambs’ behaviour in the days after birth has been examined but the longer term effects on lamb behaviour and mothering ability are not known. The behaviour of twin and triplet ewes born to ewes offered herbage with an average sward height of 2 or 6 cm from day 64 to 132 of pregnancy was recorded at 1 year of age in an arena test and at 2 years of age post lambing. A significantly (P < 0.05) greater proportion of the progeny born to dams offered 6 cm sward heights bleated in a high pitch during a 5 minute arena test. However there were no differences in minimum, median and maximum distance of the ewe from the observer or on the frequency of low- and high-pitched bleats. In addition there was no difference in the behaviour of twin- and triplet-born ewes in the arena test. At 2 years of age twin-born ewes had a significantly greater maternal behaviour score than their triplet-born counterparts. Ewe nutrition during pregnancy did not affect the maternal behaviour score of their ewe lambs after lambing at 2 years of age. These results suggest that feeding levels during pregnancy are less important than the birth rank in terms of the intergenerational effects on behaviour. KEYWORDS: ewe nutrition; lamb; behaviour; twin; triplet.

The drinking behaviour of dairy cows in late lactation - Jago JG; Roche JR; Kolver ES; Woolford MW (Proceedings of the New Zealand Society of Animal Production, 2005)
The drinking behaviour of grazing cows was investigated in two studies with the purpose of determining the suitability of using water intake as a motivator for voluntary movement of cows within a pasture-based automatic milking system (AMS). In the first study 100 mixed-age Jersey cows in late lactation were observed for 48 h. Cows drank on average 2.4 times/24 h (range: 1-6) and usually alone or with one or two other animals. Although every cow drank at least twice during the 48 h, 31% of cows recorded an interval between drinks > 24 h. Less than 1% of drinking occurred between 2000 h and 0700 h. The second study compared the drinking behaviour of Overseas (OS) and New Zealand (NZ) Holstein Friesian cows that were either grazing pasture (GRASS) or fed a Total Mixed Ration (TMR). TMR cows drank more often (5.2 times/24 h) than GRASS cows (3.5 times/24 h, P < 0.001). Feed type altered the distribution of drinking with 76.8 % of TMR cows drinking between 2000 h and 0700 h compared with only 24.5% for GRASS. Water intake was also higher for TMR (73.0 L/cow/day) compared with GRASS (53.7 L/cow/day) animals. The studies showed that the individual nature of drinking behaviour would be aligned with the AMS objectives of distributed rather than batch milking. However, the small number of cows drinking during darkness when grazing indicates that water intake would need to be used in combination with other motivators to ensure a continuous flow of cows to the dairy. KEYWORDS: drinking behaviour; grazing; dairy cows; automatic milking.

Economic comparison of Holstein-Friesian strains - Pryce JE; Harris BL; Glassey CB; Montgomerie WA; Jackson R; MacDonald KA; Thorrold BS; Holmes CW (Proceedings of the New Zealand Society of Animal Production, 2005)
The objective of this research was to identify major determinants of net profit per cow. Data were from the Dexcel strain trial over three seasons, in which Holstein-Friesian cows were managed in groups of 12 to 20 cows in eleven farmlets. Milk returns were calculated from lactation yields of milk, fat and protein. Net profit per cow was calculated as the net return from milk sales plus sales of calves minus feed, fertility, health, shed and working expense costs. Annualised present values were derived using asset replacement theory and discounting to account for different numbers of years of data according to the year in which an animal entered the herd. Net replacement costs and average replacement returns were included where animals were replaced before the end of the trial. Partition analysis was used to identify indicators of cow profitability. Partition analysis recursively sub-divides data creating a tree of partitions. Each split is chosen to maximise the difference in profitability between branches of the split. Variables on which data could be partitioned included breeding values, Breeding Worth and traits measured in first parity. The key determinants of profitability were lactation yield of protein and fat, percentage of fat and Breeding Worth. When these variables were fitted to a multiple regression model where the response was annualised present value, the adjusted R2 was 52%. KEYWORDS: asset replacement model; economics; dairy cattle.

The effect of condensed tannins in sulla (Hedysarum coronarium) on 4-methylphenol metabolism in the ovine gastrointestinal tract during late lactation - Roy NC; Fraser K; Lane GA; Sinclair BR; McNabb WC (Proceedings of the New Zealand Society of Animal Production, 2005)
Twelve lactating ewes were surgically prepared with permanent arterio-venous catheters across the gastrointestinal tract at 1 week post partum. From week 3 to 6 of lactation, all sheep were fed fresh sulla (1500 g dry matter/day; condensed tannins (CT) 4.4 g per 100 g dry matter). Half the ewes were orally drenched (4 times/day) with polyethylene glycol (PEG) (160 g/day in water) to remove the effects of the CT whilst the remaining ewes received a water drench. At week 6, para-aminohippurate was infused for 7 h into the cranial mesenteric vein for measuring mesenteric and portal plasma flow and 4-methylphenol concentrations. The mesenteric and portal plasma flows were not affected (P > 0.05) by the treatments. The concentration of 4-methylphenol in the mesenteric artery (Control: 2.8 vs PEG: 9.0 ± 1.2 μg/ml) was lower (P < 0.01) in the control ewes. The net portal appearance of 4-methylphenol was higher (P < 0.01) in the PEG ewes (Control: -663 vs PEG: -1430 ± 159 μg/minute). These results establish that sulla CT reduced the portal flux and peripheral concentration of 4-methylphenol and it is likely that this was a consequence of reduced formation of that metabolite in the rumen due to lowered ruminal protein degradation in the CT-treated ewes. KEYWORDS: plasma net fluxes; gastrointestinal tract; 4-methylphenol; lactation; sheep.

The effect of genotype on milk composition, milk value and dairy farm profitability - Thomson NA; Turner S-A; Glassey CB; Lopez-Villalobos N (Proceedings of the New Zealand Society of Animal Production, 2005)
This study was conducted to determine the effect of genotype on milk composition, milk value and economic farm surplus (EFS). The trial included two high breeding worth ($BW) strains of either North American (OS90) or New Zealand (NZ) (NZ90) genetics, and one low $BW strain of NZ genetics (NZ70). Each strain was farmed under systems designed to provide total feed allowances of 4.5 to 7.0 t DM/cow/year. For two years (2001/2002 & 2002/2003) monthly average milk yield and composition were determined for each of the 11 herds. A simulation model was used to calculate milk value using three product mixes. Using either the simulated values or actual values (paid by Fonterra 2002/2003) for milk and its components, milk value ($/litre and $/kg milksolids (MS)) and an EFS for each herd was determined. The OS90 strain produced milk with lower concentrations of fat and protein and higher protein:fat ratio than NZ70 or NZ90 strains. The effect of strain on milk price was unaffected by product mix. Milk value differed between strains irrespective of method of determination. Milk value expressed as $/kg MS was lowest for the NZ70 and highest (P < 0.001) for the OS90 strain. When expressed as $/litre milk value was highest (P < 0.001) for the NZ90 strain. Milk value expressed as $/kg MS was positively associated with protein:fat ratio whereas milk value expressed as $/litre was positively associated with MS concentration. Average EFS was greater for the NZ90 than the NZ70 strain and was least for the OS90 strain. The factors associated with EFS were MS production; milk value and milk composition had minimal impact. New Zealand’s dairy cattle breeding programme has produced a strain of Holstein- Friesian with increased milk fat and protein concentration, an increased protein:fat ratio, and an associated increased milk value and increased EFS. In comparison, the OS90 strain which the current $BW index ranks as high as the NZ90, produced milk with higher value ($/kg MS) but resulted in lower EFS. Key words: milk price; milk value; milk composition; economic farm surplus.

Effect of pre- and postpartum pasture feeding intakes on postpartum anoestrous intervals in dairy cows - Burke CR; Roche JR; Aspin PW; Lee JM; Taufa VK (Proceedings of the New Zealand Society of Animal Production, 2005)
Extended postpartum anoestrous intervals (PPAI) are the predominant source of infertility on New Zealand dairy farms. A 2 x 2 factorial design was used to investigate pre- and postpartum pasture feeding levels on PPAI. Sixty-eight multiparous Holstein-Friesian dairy cows due to calve in the first three weeks of the calving period were randomly assigned to a high (11.9 kg DM/cow/day) or low (4.8 kg DM/cow/day) pasture feeding intake for 29 ± 7.7 days pre partum. After calving, cows within each prepartum feeding level were assigned to a high (13.5 kg DM/cow/day) or low (8.6 kg DM/cow/day) pasture feeding intake for 35 days. At 35 days post partum, cows were grazed as a single group with pasture silage supplementation. Concentrations of progesterone were determined in milk samples collected on Mondays and Thursdays until cows were confirmed to have resumed oestrous cycles or until one week before planned start of mating. High intakes pre-calving increased (P < 0.05) the proportion of cows cycling by the third week postpartum (38 ± 8%) compared with a low pre-calving intake (13 ± 6%). There was a tendency (P = 0.07) for a reduced mean PPAI in the high (29.7 ± 2.6 days) versus low (33.4 ± 2.3 days) pre-calving intake treatments, among cows that initiated oestrous cycles during the experimental period. Post-calving intake did not affect PPAI (P = 0.4), nor was an interaction detected. Body condition score (BCS) at all time points in this study, including before treatments were initiated, was negatively correlated with PPAI (P < 0.05). In contrast, PPAI was not associated (P > 0.1) with changes in BCS during the pre- or post-calving periods, or with milk production characteristics. In this study, resumption of oestrous cycling post partum was strongly linked to pre-existing differences in BCS, and modified by pre-calving pasture intake, but not influenced by feeding intakes or milk production characteristics in early lactation. KEYWORDS: anoestrus; nutrition; dairy cow.

The effect of SF6 release rate, animal species and feeding conditions on estimates of methane emissions from ruminants - Vlaming JB; Clark H; Lopez-Villalobos N (Proceedings of the New Zealand Society of Animal Production, 2005)
In New Zealand methane (CH4) emissions are estimated using the sulphur hexafluoride (SF6) tracer technique. This involves inserting a calibrated source of SF6 gas into the rumen. The technique does not measure CH4 directly but estimates emissions from the ratio of CH4 to SF6 in breath samples collected continuously from above the nose of each animal. Methane estimates obtained using this method tend to be more variable than measurements obtained using respiration calorimetry. The absolute release rate of SF6 from the rumen could contribute to this variation. Data were extracted from a database containing details of 22 separate New Zealand experiments where the SF6 technique was used to estimate CH4. Experiments were divided into four groups according to species and feeding situation, with each group analysed separately. Data were analysed using a linear mixed model with a fixed effect of SF6 release rate, and random effect of experiment. In indoor fed cattle and sheep daily CH4 production was positively related to SF6 release rate (P < 0.05) but there was no relationship between SF6 release rate and daily CH4 production in grazing animals. In grazing sheep and cattle there was no significant effect of SF6 release on CH4 emitted per kg DMI. In cattle kept indoors CH4/kg DMI was positively related to permeation tube flow rate (P < 0.05) but there was no significant effect of SF6 release on CH4 emitted per kg DMI in indoor fed sheep. KEYWORDS: methane; SF6 tracer technique; ruminants.

Effect of slaughter group and sire on carcass composition and meat quality characteristics of Texel-sired lambs - PL Johnson; Purchas RW; Blair HT (Proceedings of the New Zealand Society of Animal Production, 2005)
New Zealand meat companies are investigating lamb payment systems based on lean-meat yield and meat quality. Factors that affect these traits need to be determined. Carcass composition and meat quality data from 450 Texel-cross lambs (ewe and ram) were used to evaluate the effect of sire (two sires Property One, three sires Property Two) and slaughter group. Lambs reaching target slaughter weight first (38 kg and 35 kg for ram and ewe lambs respectively) were allocated to slaughter group one, with the remainder allocated to slaughter group two and slaughtered approximately 40 days later. The average carcass weight for both groups was 17.9 ± 1.51 kg. Carcass composition traits were adjusted for carcass weight, and meat quality traits were adjusted for pH. Carcass width at the thorax and gigot was narrower in slaughter group two (P < 0.001). Trimmed leg weight and total leg muscle weight were lower (P < 0.001), whereas total leg fat weight and muscle to bone ratios were higher (P < 0.001), for slaughter group two. Femur muscularity was higher in slaughter group two (P < 0.001) for Property One only. Warner-Bratzler shear values and measures of colour (L*, a* and b*) were higher (P < 0.001), whereas cooking loss was lower (P < 0.001), for the longissimus muscle in slaughter group two. In addition, sire within property was a source of variation (P < 0.001) for all carcass composition traits and meat quality traits, with the exception of pH. These results demonstrate that both slaughter group and sire (within a breed and property) are significant sources of variation in carcass composition and meat quality traits. As a result, these need to be taken into account when making management and breeding decisions for the supply of lambs to meat companies under any future payment systems based on yield and meat quality. KEYWORDS: lamb; carcass traits; sire.

The effect of sward height during pregnancy on the wool follicle and fibre characteristics of twin and triplet born lambs - Sherlock RG; Kenyon PR; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2005)
Previous work estimating the impact of differential feeding of ewes during pregnancy, on lamb wool follicle development, has been done primarily with single- and twin-bearing ewes. The aim of this study was to compare the follicle development and fibre characteristics of twin- or triplet-born/reared lambs, born to ewes offered different sward height allowances during pregnancy and lactation. After pregnancy scanning, 186 twin- and triplet-bearing Romney ewes with 6 weeks wool growth, were randomly allocated to four different sward heights (2, 4, 6 and 8 cm). Within the first 24 hours of parturition ewes were transferred to one of two sward heights (4 and 8 cm). The wool and follicle characteristics of twin- (n = 65) and triplet-born (n = 63) ewe lambs were compared. Fleeces from triplet-born lambs were lighter (1.59 kg vs 1.82 kg, P < 0.05) and finer (32.7 μm vs 33.4 μm, P < 0.05) than those from their twin-born counterparts. Lambs born to ewes offered higher sward heights during pregnancy had increased loose wool bulk (P < 0.01). Although increasing sward height during pregnancy increased fibre diameter in twin-born lambs, there was no similar relationship for triplet-born lambs (P < 0.05). Sward height during pregnancy had no effect on secondary follicle number in twin-born lambs but, triplet-born lambs born to ewes grazed on the 4 cm sward tended to have significantly higher numbers of secondary follicles than those grazed on 6 cm (89.2 vs 66.0, P < 0.05). More work is necessary to determine whether this interaction has practical implications for breeding replacements. Nutritional treatments during lactation had no significant effects on lamb wool characteristics. KEYWORDS: feeding; nutrition; follicle development; wool bulk; wool characteristics.

Effects of feeding level for four weeks precalving on milk production is small and dependent on level of feeding in early lactation - Roche JR; Kolver ES; Lee JM; Aspin PW; Burke CR; Taylor P; Napper AR (Proceedings of the New Zealand Society of Animal Production, 2005)
The aim was to quantify the relationship between pre- and postcalving level of feeding and their effect on milk production. Sixty-eight multiparous dairy cows were randomly allocated to two levels of pasture feeding (Low and High; 4.8 and 11.9 kg DM/day) for 29 ± 7.7 days precalving. At calving, cows were randomly allocated (within precalving levels) to two levels of pasture feeding (Low and High; 8.6 and 13.5 kg DM/day) for 35 days postcalving. Daily milk yields were recorded and fat, protein and lactose concentrations determined on 2 days each week for 5 weeks postcalving, and once weekly for an additional 10 weeks post treatment. Body condition score (BCS) at calving was 4.2 and 4.7 for precalving Low and High treatment groups, respectively. Precalving restriction reduced milk fat production by 8.4% during the first five weeks postcalving, but these differences were not evident subsequently. Postcalving feed restriction reduced yields of milk, fat and protein by 25, 21 and 28%, respectively, during the first five weeks postcalving. Decreased (P < 0.05) yields of milk, fat and protein (12, 10 and 9%, respectively) were also evident for ten weeks after the feed restriction finished. There was a trend towards a treatment interaction (P = 0.13) in milksolids (MS) production during the first five weeks of lactation between pre- and postcalving level of feeding. High- High cows produced 7.1 kg more MS than Low-High cows, but there was no effect of precalving level of feeding in cows that were restricted postcalving. Results confirm that level of feeding postcalving influences the milk production effect of precalving feeding. Nevertheless the effect of precalving energy intake on postcalving milk production is small. KEYWORDS: transition cow; pasture; dry matter intake.

Effects of level of current during lamb carcase electrical stimulation on post-mortem muscle changes and meat quality - Hopkins DL; Shaw FD; Baud S; Walker PJ (Proceedings of the New Zealand Society of Animal Production, 2005)
A study was conducted using 60 lamb carcases to examine the effectiveness of a new type of stimulation system for improving meat quality of lamb carcases. There were 3 treatment groups – control (no current), low current (400 mA) and high current (800 mA). The duration of stimulation was 35 seconds, 20 minutes after death. The stimulation treatments both significantly increased the rate of pH decline and caused an increase in the redness of the longissimus thoracis et lumborum muscle. There was no significant reduction in shear force due to stimulation, but ageing for 4 vs 2 days significantly (P < 0.001) decreased shear force by on average 12.6 N. There were no significant effects of stimulation on sensory traits, but, as for shear force, ageing significantly (P < 0.001) improved tenderness (60 vs 65 on a 0-100 scale). The lack of effect of stimulation may have been due to the high initial tenderness and liking scores of the control samples. These high values occurred in spite of a chilling rate under which cold-induced toughness, and, hence, low tenderness and liking scores, would have been expected. KEYWORDS: lamb; electrical stimulation; eating quality.

The effects of once a day milking on mastitis and somatic cell count - Lacy-Hulbert SJ; Dalley DE; Clark DA (Proceedings of the New Zealand Society of Animal Production, 2005)
A four-year study examined the effect of once a day (OAD) milking for complete lactations on mastitis and milk quality. The study comprised two herds of Jersey cows and two of Friesian cows, milked either OAD or twice a day (TAD) for a total of 4 lactations. Prevalence of intramammary infection (IMI) was determined by isolation of mastitis pathogens from quarter foremilk samples, collected aseptically at calving, mid lactation and at drying off. In the second and third years of the study, at drying off, cows milked OAD had three times as many (P < 0.01) quarters with IMI by major mastitis pathogens compared with TAD cows. Across all pathogens and years however, prevalence of IMI was not significantly or consistently higher for cows milked OAD compared with TAD. The somatic cell count (SCC) for uninfected cows milked OAD was approximately double that for TAD milked cows although this difference was only significant (P < 0.05) after the first 1-2 months of lactation had elapsed. Cows with minor or major pathogen infections also showed an approximate doubling of the SCC if milked OAD. Results suggest that milking OAD consistently increases the individual cow SCC but does not significantly increase prevalence of mastitis. KEYWORDS: once daily milking; mastitis; SCC; milk quality; milking frequency.

Estimation of lactation persistency in crossbred grazing dairy cattle - Lopez-Villalobos N; Spelman RJ; Harris BL; Stanley G; Harcourt S (Proceedings of the New Zealand Society of Animal Production, 2005)
Lactation persistency is commonly referred to as the rate of decline in daily yield after the peak of lactation and can be measured in different ways. The objective of this study was to calculate different measures of persistency for milk traits and estimate the correlations between parameters of the lactation curve in crossbred cattle. Herd test records of milk, fat, protein and lactose from 810 first lactation cows were used to obtain individual lactation curves using a mixed model fitting six knots splines. The model included the fixed effects of contemporary group (year-calving week), sire, age at calving (linear and quadratic) and an average spline and the random effect of cow-spline interaction. All cows were in their first lactation, second cross Friesian x Jersey from a crossbreeding experiment established for quantitative trait loci identification. Persistency was measured in three different ways: P1, slope of the line fitted using linear regression of daily yield on day of lactation from day 60 to day 220; P2, the area under the lactation curve from day 121 to 180 divided by the area under the curve from day 1 to 60; and P3, the 240-day lactation yield divided by peak yield multiplied by 240. Correlations between measurements of persistency ranged from 0.24 to 0.81 and were significantly different to zero (P < 0.001). Correlations between lactation yield and measurements of persistency ranged from -0.43 to +0.33 and were significantly different to zero (P < 0.01). These results indicate that measurements of persistency are not invariant and highlight the need to calculate persistency in a more consistent way. When cows were classified for persistency P2 of fat plus protein, cows of high persistency (top 25%), compared with cows of low persistency (bottom 25%), had significantly (P < 0.05) more days in milk, higher total yields of milk and its components, lower peak yields, later day of peak yield and lower rate of decline in daily yield from day 60 to day 220 (P1), but similar 240-day total yield of fat and protein. Farming cows of high persistency may be an alternative to reduce farm investments in peak notes and risks of metabolic problems and reproductive failures. KEYWORDS: lactation persistency; milk yield.

Exploiting cow genotype to increase milk value through production of minor milk components - Back PJ; Thomson NA (Proceedings of the New Zealand Society of Animal Production, 2005)
Milk value could be increased on-farm by supplying milk with enhanced concentrations of minor compounds that have bioactive properties. Compounds of interest in this study were the whey proteins lactoferrin (Lf) and lactoperioxidase (LP), and milk fatty acids; particularly conjugated linoleic acid (CLA) and omega-3 fatty acids. Mixed genotype cows (20 Friesian, 20 Jersey and 20 crossbred) were sampled to determine the effect of cow genotype and age on Lf concentration, Lf yield and LP activity at 4 times during the season. In milk fat, concentration of CLA and omega-3 fatty acids were determined twice during the season. Cow genotype had no effect on Lf concentration but age did (P < 0.002), with 4-year and older cows producing greater concentrations in milk than 3 year old cows. For harvesting Lf, Friesian cows would be the most profitable, with the greatest Lf yields, particularly in mid-late lactation. The highest LP activity levels throughout lactation were demonstrated in Jersey milk. In milk fat, Friesian cows produced milk of a putatively healthier profile, with greater concentrations of unsaturated fatty acids, CLA and omega-3 fatty acids. Key words: milk value; cow genotype; lactoferrin; lactoperoxidase; conjugated linoleic acid; omega-3 fatty acids.

Factors affecting methane production in Friesian x Jersey dairy cattle - McNaughton LR; Berry DP; Clark H; PinaresPatino C; Harcourt S; Spelman RJ (Proceedings of the New Zealand Society of Animal Production, 2005)
Methane production was measured in 301, 3-year-old Friesian x Jersey dairy cows, during summer 2004 in stage one of a project to define phenotypes for quantitative trait loci (QTL) mapping and to investigate the relationships between CH4 and milk production. Animals were allocated into four groups and their methane production was measured during four days. Feed intake was estimated by the alkane technique and by prediction equations. Correlations between the alkane technique and prediction equations were all less than 0.37, but correlations amongst the prediction equations were greater than 0.61. Daily CH4 output varied from 210 to 498 g and averaged 332 g. Dry matter intake averaged 19.3 g/kg DM. Milk production and live weight gain were negatively related to CH4 production per kg dry matter intake. Sire was not found to have a significant effect on CH4 output per kg of dry matter; however, only six sires are represented in the trial. The CH4 output recorded in the current study was within the ranges observed in other studies and was repeatable between days. High quality data were generated for the QTL study. KEYWORDS: methane; herbage intake; alkanes; dairy cows.

Factors influencing milk harvesting efficiency in an automatic milking system - Davis KL; Jago JG; Wieliczko R; Copeman PJA; Bright K; Woolford MW (Proceedings of the New Zealand Society of Animal Production, 2005)
Maximising milk harvested per robot is an important goal of pasture-based automatic milking systems (AMS). Results are presented from an analysis of 2937 cow milkings in a year-round milking system during January 2003 at the Dexcel Automatic farm (average herd size = 75 cows). Each cow milking was classified as OK (yield > 80% of expected yield, EY), Yield Carry Over (YCO, 20% < yield < 80% EY), or Failed (F, yield < 20% EY). The time and duration (from entry to exit from crate) of each cow milking was determined, as well as milk yield, and from these milk harvesting rate was calculated. There were an average of 95.8 cow milkings/day, average milking frequency was 1.13 milkings/cow/day (range 0.9 – 1.9 milkings/cow/day). Eighty-four percent of milkings were classified as OK, 8.9% as YCO and 7.1% as F (after which the cow was returned to the yard for another attempt). Milking times ± SD (F = 3.76 ± 2.57, YCO = 7.63 ± 3.31, OK = 10.07 ± 4.09 minutes/event) and milk harvesting rate (F = 0.09, YCO = 0.76 and OK = 1.37 kg/minute) suggest that failed milkings were costly in terms of time. The data show potential for improving the 24 h milk harvest per AMS through cow selection, a more consistent flow of cows through the AMS and technological improvements. KEYWORDS: milk harvesting efficiency; automatic milking systems; grazing; dairy cows.

Feeding maize silage to dairy cows : implications for methane emissions - Waugh CD; Clark DA; Waghorn GC; Woodward SL (Proceedings of the New Zealand Society of Animal Production, 2005)
Maize silage was used on 25% of New Zealand dairy farms in 2003/2004, with 26% of these farms feeding 2 t DM/ha as maize silage. The nutritional value and animal responses to maize silage fed with pasture are well defined, but its impact on rumen methane emissions is not. In an 11-day indoor feeding trial, 32 Friesian dairy cows in mid lactation were fed ad libitum pasture with 0, 12, 24 and 36% of the dry matter (DM) intake supplied by maize silage. Pasture and maize silage intakes, milk production and methane emissions were measured. Half of the cows in each treatment group were given intra-ruminal slow release monensin capsules. Total DM intakes were similar for all feed treatments. As maize silage intake increased, milksolids (MS) production decreased linearly from 1.73 (pasture only) to 1.46 kg/day (P = 0.0043, SED = 0.09) and methane emissions increased from 16.3 to 19.0 g/kg DMI (P = 0.0061, SED = 1.03). Increasing proportions of maize silage in a pasture-based diet increased methane emissions from lactating dairy cows. These effects were alleviated by monensin. KEYWORDS: dairy cows; methane emissions; milk production; perennial ryegrass; maize silage.

Further testing of the effect of a calpain-1 variant on meat tenderness in cattle - Cullen NG; Morris CA; Veenvliet BA; Hickey SM; Dobbie PM; Wilson T (Proceedings of the New Zealand Society of Animal Production, 2005)
We have previously reported that a single-nucleotide polymorphism (SNP) on the large subunit of micro-calpain (the calcium-activated neutral protease-1 gene) is associated with differences in tenderness, as measured in cooked steaks from the longissimus dorsi of animals from the AgResearch Jersey-Limousin Beef DNA-marker trial. The effect was significant at the intermediate stages of the tenderising process and had little effect on initial or ultimate tenderness, so that tenderising was accelerated in animals having one or two copies of the favourable variant. We have now analysed tenderness and genotype data from 310 additional animals, comprising Hereford-cross and pure Angus breeds slaughtered under varying conditions of electrical stimulation and aged at a range of temperatures. Results in all cases support the original finding: animals with two copies of the `C` allele (the SNP on Exon-9 encoding alanine at amino acid number 316) have more tender meat (decreased shear force) at the intermediate stages than animals with two copies of the `G` allele (encoding glycine). Combining measurements from three intermediate cook times, mean shear forces from `CG` were less than from `GG` genotypes by 0.80 ± 0.29 kg (P < 0.01), and mean shear forces from `CC` were less than from `CG` genotypes by 1.19 ± 0.36 kg (P < 0.001). These results show that a genotype substitution from `GG` to `CC` is associated with a difference in shear force in longissimus dorsi steaks of approximately 20% at intermediate aging times. KEYWORDS: cattle; meat; tenderness; micro-calpain; SNP.

Generating value from differentiated milk products - South C (Proceedings of the New Zealand Society of Animal Production, 2005)
There is an identified consumer demand for foods that promote health and wellness. To address this need Fonterra is developing products with proof of efficacy for a range of clinical indications, providing health and wellness to customers through novel customer solutions derived from milk. Novel approaches to generating and processing these foods are necessary to manufacture products with this proven efficacy. These health benefits…

Is goat meat acceptable to Japanese youth? The first goat meat taste survey in Japan - Ozawa T; Lopez-Villalobos N; Blair HT (Proceedings of the New Zealand Society of Animal Production, 2005)
Two sensory evaluations of goat meat were carried out to examine the acceptance of goat meat by Japanese youth. The first test used 172 university students to examine the preference between loin and hind leg of domestic goat. The second test employed 35 university students to rate taste differences between loin and fillet. The sensory analysis between loin and hind leg showed that ‘chewiness’ in goat meat was highly rated. Also loin meat was relatively highly evaluated in comparison with hind leg meat. Fillet meat obtained slightly higher evaluation in comparison with loin meat. Due to the expense of goat meat at retail outlets in Japan, New Zealand could have an advantage of shipping loin and fillet goat meat to meet the future demand by Japanese youth. KEYWORDS: goat; meat: sensory test; Japan.

How can we make better use of traceability? - Nortje GL (Proceedings of the New Zealand Society of Animal Production, 2005)
Traceability is rapidly becoming a way of doing business in the food industry. Companies have a choice of regarding it as a compliance requirement or to utilise the newly available technologies to capture data regarding full supply chain and product attributes. By having the relevant data available it can be analysed to unlock previously unavailable information regarding business processes and attributes while providing compliance traceability by default. Depending on this choice, traceability can either be a compliance cost or it can add value to an enterprise. KEYWORDS: value traceability; attribute traceability; compliance.

Identification of cattle and deer as a movement traceability aid in the eradication of bovine tuberculosis - Hancox N (Proceedings of the New Zealand Society of Animal Production, 2005)
The Biosecurity (Animal Identifications Systems) Regulations 1999 oblige the owners of cattle and deer to use an identification (ID) system, that has been approved under those regulations, when moving cattle or deer aged over 30 days of age. The use of such an identification system is required for the purposes of the National Bovine Tuberculosis Pest Management Strategy (NBTPMS). It involves the permanent unique identification of cattle and deer to the herd from which they are first moved after 30 days of age. The ID technology currently employed consists of optically read ear-tags. Two approved ID systems are currently in place. One is operated by the Animal Health Board (AHB system) and is mostly used by beef and deer farmers. The Livestock Improvement Corporation provides a system (the LIC MINDA system) that has many additional identification functions required within the dairy industry. KEYWORDS: deer; cattle; identification; movement; disease control.

Identifying opportunities to add value to the New Zealand beef industry : a modelling approach - McDermott A; Dooley AE; Smeaton DC (Proceedings of the New Zealand Society of Animal Production, 2005)
A model of the New Zealand beef value chain, from conception to export, was constructed. The model is parameterised at the national level so that issues and opportunities within the beef industry can be examined at a high level by researchers and industry participants. Working with numerous key informants from throughout the beef industry, the researchers developed a conceptual model of the beef value chain and then constructed the model in a spreadsheet. The model is capable of modelling changes in farm practice, market situations and the industry structure. This model and a range of scenarios have been demonstrated to a range of beef industry participants facilitating considerable debate. To illustrate the power and value of the model in evaluating change and facilitating debate within the beef sector, three scenarios are presented and compared with the status quo. KEYWORDS: value chain; scenario evaluation; beef; model.

Immunity in pregnant ewes following a live-dead vaccination and infection with Salmonella Brandenburg - Li H; McFarlane RG; Amoafo OY; Zhang XZ (Proceedings of the New Zealand Society of Animal Production, 2005)
The aim of this study was to investigate the efficacy of a combined live–dead vaccination protocol to protect sheep against Salmonella Brandenburg infection. Thirty ewes were randomly divided into two groups, one of which was vaccinated and the other acted as a control. The vaccinated group received a live modified Salmonella Typhimurium vaccine (given by eye-drop) followed 4 weeks later by a sub-unit preparation derived from S. Brandenburg (given subcutaneously with the adjuvant Quil A). Following challenge with wild type S. Brandenburg (4 weeks after the booster), 43% of the ewes aborted in the vaccine group as compared with 53% of the controls. However, a higher mortality rate was found in the vaccine group (43% vs 20%). Using an enrichment/selection procedure, S. Brandenburg was detected in the faeces of all challenged animals until 3 weeks post challenge. By 6 weeks and 9 weeks post challenge approximately 50% and 30% of animals respectively were shedding, irrespective of treatment. Following administration of the live primary and subunit (secondary) vaccines, levels of total IgG, IgG1 and IgM antibody (measured with an indirect ELISA) were significantly increased in comparison with the control group (P < 0.01). The cell-mediated immune response (interferon gamma from whole blood cultures) was also enhanced following use of the live attenuated vaccine (P < 0.01), but was much less pronounced after boosting with the subunit vaccine and following challenge. In summary, vaccination evoked immune responses but did not give protection to experimental infection with S. Brandenburg.

Impact of farm management decision rules on the production and profit of different strains of Holstein-Friesian dairy cows - MacDonald KA; Thorrold BS; Glassey CB; Holmes CW; Pryce JE (Proceedings of the New Zealand Society of Animal Production, 2005)
Management decision rules (‘old’ rules) have been used at the Dexcel No. 2 Dairy Farm to remove subjectivity from the management of farm systems research and have also been promoted to the dairy industry. A trial involving these rules where three strains of Holstein-Friesian (HF) cows were compared has completed its third season. The trial included two high breeding worth (BW) strains of either North American (OS90) or New Zealand (NZ90) genetics, and one low BW strain of NZ genetics (NZ70). Under the ‘old’ rules the OS90 cows had fewer days in milk than the other two strains, mainly because they were dried off earlier due to their lower body condition score (BCS). In the third lactation ‘new’ rules were applied that allowed cows at the higher feed allowances to be dried off later (but at the same BCS) than would have been allowed under the ‘old’ rules. For the herds receiving the higher feed allowances, this change resulted in increased days in milk (NZ90 + 2 days; OS90 + 17 days) more milksolids (MS) per cow (NZ90 +2 kg; OS90 +21 kg), and more feed required (NZ90 + 10 kg; OS90 + 157 kg DM/cow) with all herds reaching target BCS by their next calving. It is calculated that this reduced the difference in economic farm surplus (EFS) per ha between the NZ90 and OS90 from $488 to $219. These results indicate the need to alter management rules to get the best performance from North American HF genetics. KEYWORDS: Holstein-Friesian; body condition score; drying-off decision rules.

Impact of monensin on methane production and performance of cows fed forage diets - Van Vugt SJ; Waghorn GC; Clark DA; Woodward SL (Proceedings of the New Zealand Society of Animal Production, 2005)
Monensin is an ionophore used to increase the efficiency of feed utilisation when grain-based rations are fed to beef cattle, but it can also lower energy losses to methane. A series of feeding experiments has been undertaken to measure the impact of monensin on methane production by dairy cows fed ryegrass-dominant pastures alone or with white clover, or maize silage. Methane production measured from 15 sets of identical twin cows fed indoors was reduced by 9%, from 16.9 to 15.3 g/kg dry matter (DM; P < 0.01), and remained 10% lower (P < 0.05) than Controls 72 days after the monensin capsule was given. When pasture was substituted with maize silage at 12, 24 and 36% of DM intake, monensin reduced methane (g/kg DM) by 1, 6.5 and 10.5 % respectively (P = 0.05). However, methane emissions were not affected in cows fed pasture with white clover at 15, 30 or 60% of DM intake. Although monensin provides an important opportunity for methane reduction, the data demonstrate a need to understand reasons for variable responses to treatments under differing nutritional regimes. The added benefits of improved feed efficiency and reduced bloat suggest further investigation of monensin for forage fed ruminants is warranted. Keywords: monensin; dairy cows; methane; pasture; white clover; maize silage.

Influence of dairy cow genotype on milksolids, body condition and reproduction response to concentrate supplementation - Kolver ES; Roche JR; Burke CR; Aspin PW (Proceedings of the New Zealand Society of Animal Production, 2005)
Responses to supplementary feeding overseas (OS) and New Zealand (NZ) Holstein-Friesian (HF) cows were investigated over two years using 57 cows receiving a high pasture allowance and 0, 3 or 6 kg concentrate DM/cow/day. Cows of similar Breeding Worth ($BW) grazed as a single herd and were individually fed a grain-based supplement. Important production genotype x diet interactions of a scaling nature were detected. Across all supplementation levels, OS cows gave a greater (P < 0.05) linear production response than NZ cows (74 vs 37 g MS/kg concentrate DM; 1.22 vs 0.67 kg milk/kg concentrate DM consumed, respectively), but gave a similar response in live weight and condition score gain during lactation per kg of concentrate DM consumed. However, because OS HF appeared to have a larger relative feed deficit than NZ HF when fed ad libitum on pasture, OS HF maintained a lower body condition score throughout lactation and produced less milksolids (as a % of live weight). Current supplementary feeding decision rules which recommend reducing supplementary feed use when abundant pasture is available remain appropriate for high $BW NZ HF cows. However, reasonable responses to high-energy supplements will continue to be obtained from high $BW OS HF cows, even when pasture supply appears adequate to meet cow requirements. Use of indicators of relative feed deficit such as milksolids as a % of live weight and body condition score, may be a better guide to predicting the production response to supplementation, rather than decision rules based on genotype. KEYWORDS: Holstein-Friesian; genotype; supplements.

Lamb survival: a new examination of an old problem - Kerslake JI; Everett-Hincks JM; Campbell AW (Proceedings of the New Zealand Society of Animal Production, 2005)
The overall aim of this project is to identify genetic markers for lamb survival. This paper reports the results from the first stage of the investigation aimed to identify the primary causes of lamb death from parturition to three days of age for highly fecund flocks. Flocks in the study consisted of 9 breeds and 12,000 breeding ewes and were located in New Zealand regions; Southland, Otago and Manawatu. All lambs were tagged and identified to their dam and sire. Lambs dead at birth and up to three days of age were collected (n = 1529), weighed, measured and examined by post mortem to determine cause and time of death. Primary causes of lamb death included: dystocia, starvation/exposure, amnion over nose, organ rupture, disease, and unknown. The mean mortality rate from birth to weaning for the 20 flocks studied was 14 ± 0.6% (SEM) in singles, 16 ± 0.3% in twins and 29 ± 0.6% in triplets. The study showed that the predominant primary cause of lamb deaths from parturition to three days of age was dystocia (difficult births). The dystocia rate was highest for dead single lambs (57 ± 4.2% SEM) (P < 0.05), where there was an unexpectedly high incidence for dystocia for dead twin (46 ± 1.7% SEM) and triplet lambs (48 ± 2.3% SEM). This suggests that dystocia as a primary cause of lamb death may be underestimated within highly fecund sheep flocks. The high death rate from dystocia in twin and triplet lambs has not been previously reported and is currently under further investigation. KEYWORDS: lamb survival; dystocia; post-mortem; cause of death; mortality; genetic; phenotypic.

Mathematical modelling of anoestrus in dairy cows and the linkage to nutrition - Smith JF; Soboleva TK; Peterson AJ; Pleasants AB; Chagas LM; Burke CR (Proceedings of the New Zealand Society of Animal Production, 2005)
Postpartum anoestrus is a major reproductive problem in New Zealand dairy cows and its duration is related to the nutrition levels both pre and post calving. However, the mechanistic details of this relationship are largely unknown. A better understanding of the interactions between nutritional status, and the levels of the reproductive hormones controlling follicle development and ovulation is needed. A mathematical model consisting of a set of interactive nonlinear differential equations and describing the dynamics of the interactions among luteinising hormone (LH), follicle stimulating hormone (FSH) and oestradiol was developed. The model depicts oestradiol profiles generated by individual follicles from the first follicular wave after calving until ovulation, and changes in LH pulsatility leading to the first pre-ovulatory surge are also produced. The robustness of the model was ascertained from iterative processes, and it was also checked against existing experimental data so as to mimic observed changes in hormone levels. It was shown that two mathematical parameters which control: i) the speed of changes in the feedback of LH activity to oestradiol; and, ii) the sensitivity of the ovarian response to LH, have the greatest effect on duration of anoestrus. KEYWORDS: mathematical model; anoestrus; dairy cows; nutrition; oestradiol; LH; FSH.

Meat industry by-products : a cunningly disguised opportunity - Rogerson A (Proceedings of the New Zealand Society of Animal Production, 2005)
A pharmaceuticals division was first established in a New Zealand (NZ) meat company by Richmond Limited in mid 2001. This new division was a first in Australasia and had the stated objective of adding value to a range of relatively low-value by-products. At that time the supply of by-products throughout the meat industry in NZ was generally characterised by: • low prices; • low level of attention; • low levels of enthusiasm; • lack of market knowledge. This presentation will attempt to: • describe, in general terms, the establishment of a pharmaceuticals division as an integral part of a meat company; • describe the process of establishing relationships between suppliers and customers; • highlight areas of particular strengths and weakness in the pharmaceuticals arena for the NZ meat industry; • make some observations about the medium and longer term prognosis for the industry, in its widest sense.

Milk production in East Friesian-cross ewes lambing year round - Peterson SW; Kenyon PR; Morris ST; Lopez-Villalobos N; Morel PCH (Proceedings of the New Zealand Society of Animal Production, 2005)
Milk production of groups of East Friesian cross ewes lambing at intervals of 73 days (i.e., five times per year: August (n = 21), November (n = 29), January (n = 13), March (n = 14) and June (n = 14)) was measured on alternate days in the first week post partum and at weekly intervals for nine weeks. Ewes with single and twin lambs were enrolled if they safely delivered the appropriate number of lambs indicated by previous scanning. Ewes and lambs were separated in the morning and ewes milked by machine following i.v. oxytocin (1 i.u.) and stripped by hand until empty. Ewes returned to pasture whilst lambs were housed and bottle-fed. At afternoon milking (after a precisely measured interval of about 6 h) milk yields were recorded. From that yield and the time interval, daily milk yields were calculated. Data were analysed using a mixed linear model for repeated measures. Twin-bearing ewes produced significantly more milk than single-bearing ewes (P < 0.001). Lactogenesis differed significantly (P < 0.001) between the lambing groups. Over the whole lactation, milk yield differed significantly (P < 0.001) between different lambing groups. Milk yields were highest following June lambing (2223 ± 35 g/day), followed by November (2107 ± 24 g/d), August (1932 ± 36 g/day), January (1826 ± 31 g/day) and March (1742 ± 30 g/day). A significant lambing group by rearing rank interaction (P < 0.001) indicated that single- and twin-bearing ewes responded differently to seasonal differences; ewes with twins increased milk yield proportionately more than ewes with singles in June, November and January. KEYWORDS: milk yields; sheep; STAR system.

A model system to investigate the regulation of lactoferrin production by the bovine mammary gland - Turner S-A; Thomson NA (Proceedings of the New Zealand Society of Animal Production, 2005)
Lactoferrin (Lf) is a high value, low concentration protein found in milk. Lf concentrations are found to increase during mastitis. This study was instigated to investigate if the effect of inducing sterile inflammation of the mammary gland, using lipopolysaccharide (LPS), a component of bacterial cell walls, would be a useful physiological model to study the production of Lf. Ten multiparous Friesian-Jersey cross-bred (FxJ) cows (approximately 200 days in milk) with no recent history of mastitis were utilised. All cows were milked on an individual quarter basis, and milk samples were collected one week prior to the treatment date to provide covariate data. Eight cows were infused via the teat canal with 10 ml saline and 10 μg LPS in 10 ml saline into 2 random quarters on each cow. The other two quarters on each cow were not treated. Two cows were untreated controls. All cows were milked twice daily with milk samples collected individually from all 4 quarters for 7 days with additional samples collected at 14 and 21 days. All milk samples were analysed for gross composition (fat, protein, lactose), somatic cell count (SCC), conductivity and Lf concentration. At the first milking after treatment, LPS treatment showed a significant effect on all milk components measured. By the 4th milking after treatment Lf concentrations were approximately 3.5 fold higher in LPS treated quarters compared with saline infused quarters, and remained elevated until 7 days after treatment. SCC remained elevated (P < 0.01) in the LPS treated quarters until day 7 also. These results show that LPS can be used to induce the production of Lf in lactating cows and therefore provides a model with which to further investigate the mechanisms that control Lf production. KEYWORDS: lactoferrin; lipopolysaccharide; endotoxin; somatic cell count; conductivity; milk composition.

Modelling dairy system efficiencies - Jensen RN; Beukes PC; Clark DA; MacDonald KA (Proceedings of the New Zealand Society of Animal Production, 2005)
The Dexcel Whole Farm Model (WFM) is being developed to simulate dairy systems based on the interaction of system components. The WFM was fitted against observed data from the Resource Efficient Dairying (RED) trial, Scott Farm, Hamilton (Treatment A, 2002/2003 season) and used to explore the effects of different stocking rates on measures of system efficiency, i.e. feed utilisation (FU) and feed conversion efficiency (FCE). At the same stocking rate as RED treatment A (3 cows/ha), and with the observed ‘bestpractice’ management principles in place, the WFM predicted a FU 7% higher compared with the observed (73% vs 66%). Increasing stocking rate in the WFM resulted in an increase in FU, but the predicted FCE did not decrease as was expected. The model showed the importance of adhering to proven management principles to reduce feed wastage and thereby improve system efficiencies. Key words: stocking rate; simulation modelling; pasture utilisation; dairy farm.

Modelling the effects of zero-inductions on profitability in dairy systems - Beukes PC; Thorrold BS; Wastney ME; Glassey CB; Burke CR; Van Bysterveldt AM (Proceedings of the New Zealand Society of Animal Production, 2005)
Inductions are an animal welfare issue and regulations aim to achieve < 2% inductions on a national basis by 2010. There is a need to assess the longer-term impacts of alternative reproduction management strategies on farm economics and their success in solving the problem of poor reproductive performance. Dexcel’s Whole Farm Model was calibrated against observed data from Lincoln University Dairy Farm where 11% of the herd was subjected to inductions in the 2002/03 season, but a zero-induction policy has since been adopted. Results from one-year simulations over five different climate years showed a significant decrease in farm profit ($105/ha, P < 0.05) from the benchmark farm with 11% inductions (following ‘best practice’ guidelines) to a farm where the late-calvers were culled and replaced by bought-in early-calving heifers and where stocking rate was raised moderately (< 10%) to compensate for the higher proportion of heifers in the herd. Multiple-year simulations reflecting carry-over effects showed that a strategy with a 10-week mating period, annual culling of 25% of the herd including all empties and replacement with synchronized heifers mated to start calving one week before planned start of calving can match the farm profitability of the ‘Induction’ strategy if implemented consistently for 5-8 years. Key words: calving spread; modelling; synchrony; mating; replacement.

National genetic evaluation for somatic cell score - Harris BL; Winkelman AM; Montgomerie WA (Proceedings of the New Zealand Society of Animal Production, 2005)
The method for the national genetic evaluation of somatic cell score (SCS) in New Zealand is described. Evaluation was done using a multiple-trait random regression test day animal model. Trait one was the first-lactation SCS record and trait two was the records from the second and third lactations. Third-order Legendre polynomials of days in milk were fitted to the genetic and cow effects. The evaluation was done across breed. In the first national evaluation, the pedigree contained 15.9 million animals. There were 22.7 million first lactation test day records and 35.4 million second/third lactation test day records. Solutions were obtained using a preconditioned conjugate gradient solver and iteration on data. The resulting breeding values (BVs) indicate a small annual increase (0.01 to 0.03 genetic standard deviation units) in SCS. The range in sire BVs indicate the potential to select for decreased SCS. KEYWORDS: somatic cell score; genetic evaluation; test day model; dairy cows.

New versions and uses for wool - Kelly RJ; Foulds BK; Sigurjonsson F; Roddick-Lanzilotta A (Proceedings of the New Zealand Society of Animal Production, 2005)
Based on a strong understanding of wool and its components, and strong support for the science behind those components and their application, Keratec Limited has created new versions and uses of wool, as keratin protein products in a range of markets, including personal care, medical devices and consumer health. The scientific approach taken by Keratec Limited, and recent developments in each of the target product areas will be discussed.

Novel versions and uses for animal products - Nicol AM (Proceedings of the New Zealand Society of Animal Production, 2005)
The genesis of this contract session was a perceived need for an update on the progress being made in the well-documented objective of those involved in the processing and marketing of animal products to move at least a proportion of what was historically a commodity into more valuable market niches. The potential of entry into the apparently lucrative markets of functional foods, pharma- and nutraceuticals, human medicine, and health and wellness has spawned new areas of research and development…

Predicting next oestrous date and drafting automatically milked cows for focused attention on oestrous detection - Burke CR; Davis KL; Jago JG (Proceedings of the New Zealand Society of Animal Production, 2005)
The autumn-calving herd at the Dexcel Automatic milking farm was used to test a system of predicting next oestrous date for individual cows and automatically drafting them for focused observation of behavioural oestrus. During the first 21 days of artificial inseminations (AI), the automatic milking system was programmed to draft cows into a holding paddock on each of three days either side of the due date for next oestrus, which was predicted from oestrous dates and milk progesterone concentrations collected prior to the planned start of mating. Cows drafted into the holding paddock were visually checked in the morning, released if not in oestrus or retained if in oestrus for AI later in the morning. The remainder of the herd was also visually checked for oestrus in the morning and afternoon. During the first 21 days of mating, 29 of the 37 cows (78%) were inseminated, and 22 (76%) of these were inseminated within the predicted ‘six-day separation window’. Of these 22 cows, 15 (68%) were detected as being in oestrus after being drafted into the holding paddock. A system for drafting cows due to be in oestrus for focused observation is achievable in practice, although improved performance will be necessary to reach the desired level of reliability. KEYWORDS: oestrous detection; automation; dairy cattle.

Preliminary examination of the New Zealand event horse production system - Rogers CW; Firth EC (Proceedings of the New Zealand Society of Animal Production, 2005)
Three day eventing is a sport that places large physical demands on the equine athlete and is a considerable export earner. However there are no published data concerning the size or scope of the New Zealand event horse production system. Quantification of the current production system is important for development of animal breeding programmes and the minimisation of wastage. Retrospective data were obtained from the Equestrian Sports New Zealand horse and rider databases for the 1994/95 to 2000/2001 competition seasons. Basic descriptive statistics were used to describe the horse population. The competitive life of horses registered for the sport of eventing was tested using survival analysis (Kaplan-Meier). Log rank test was used to test the effects of age, sex, breed, horse grade and rider level on survival. In the 1994/95 season 1612 horses were registered for eventing (5% in advanced, 15% intermediate and 81% in novice grades). Mean horse age was 9.7 ± 3 years and 75% of the horses were geldings. Thirteen breed categories were identified, most horses being either Thoroughbred (46.2%) or unrecorded (43%). Only 56% of the horses registered in the 1994/95 season were still registered six years later. There was no effect of sex, breed, or rider level on survival. Advanced and novice horses had poorer cumulative survival than intermediate horses (40%, 55%, and 64% respectively; log rank 12.06, P < 0.001). Not unexpectedly, survival was related to age with horses aged >10 years in the 1994/95 season having a lower cumulative survival (47%) than horses aged < 6 years (60%) or aged 7-10 years (63%) (log rank 25.15, P < 0.01). It appears that novice horses leave the system because of sale or lack of talent. The greater relative loss of advanced horses may reflect either the age of the horses once they reach advanced grade, or possibly the relentless work associated with training and competition. Further prospective study is required to quantify the reasons for loss in the various age and grade categories. KEYWORDS: horse; event horse; wastage; industry structure.

Presidential Address 2004: The changing face of animal science in society - Jopson NB (Proceedings of the New Zealand Society of Animal Production, 2005)
It is a very interesting exercise to go back to the first few editions of our own proceedings and examine the areas of research that occupied the attentions of our members around 60 years ago. While the tools we use today are far superior to the techniques of their day, many of the questions asked have changed little over that time. Our research is still mostly related to how we can make better or more efficient use of our animal and land resources to produce a range of products to suit the markets of the day. However, what has changed significantly over that period is what society considers to be acceptable use of our animal and land resources…

The productivity of pasture-based dairy farms in New Zealand with different levels of extra feed input - Silva-Villacorta D; Holmes CW; Shadbolt NM; Lopez-Villalobos N; Prewer W; Glassey CB; Blackwell M (Proceedings of the New Zealand Society of Animal Production, 2005)
The objective of this research was to study the physical and financial performance of commercial dairy farms in New Zealand that differed in the amount of extra feed used. Data from Dexcel’s ProfitWatch corresponding to 626 owner-operated dairy farms between 1998/1999 and 2001/2002 were analysed. The data were classified according to each of the four dairy seasons and the extra feed used per cow. Extra feed comprised supplements imported (hay, pasture silage, maize silage, concentrates and other feeds), winter grazing and maize silage grown on the farm. The statistical analyses were done in SAS and comprised analyses of variance and regression analyses. High feed input farms (H farms, 740-940 kg extra DM /cow/year) had higher stocking rates (2.7-2.8 vs 2.4-2.5 cows/ha), lower comparative stocking rate (83-86 vs 83-92 kg live weight/t DM), and higher milksolids (MS) production per cow (293-341 vs 249-295 kg MS/cow) and per hectare (826-921 vs 616-744 kg/ha) than low feed input farms (L farms, 20 kg DM extra feed/cow/year). The use of nitrogen fertiliser was also higher in the H farms than in L farms (85-116 vs 53-67 kg N/ha/year). There were no significant differences in farm size, herd breeding worth, reproductive characteristics of the herds and estimated pasture consumed per hectare. On average, extra feed was significantly associated with extra cows (0.17 extra cows/ha for 1 t extra DM) and extra milk solids (50 g extra MS/cow for 1 kg extra DM/cow and 96 g extra MS/ha for 1 kg extra DM/ha), but the wide variability is shown by the low values for R2 (0.13 to 0.16 for the three relations above). The H farms produced higher gross farm incomes per hectare (by $0.47 to $0.49/kg extra DM offered) but had higher farm working expenses per hectare (by $0.36 to $0.37/kg extra DM offered), so that Economic Farm Surplus per hectare was not higher for these farms in any year. High management skills and control of costs are necessary for profit to be increased by the use of extra feeds. KEYWORDS: low-input; high-input; extra feed.

Puberty in red deer hinds : (1) Onset of luteal and mating activity - Scott IC; Asher GW; O'Neill KT; Littlejohn RP (Proceedings of the New Zealand Society of Animal Production, 2005)
Pregnancy rate of yearling (15-18 months) red deer hinds may be influenced by time that puberty is attained, especially if stags are removed before all hinds have had a chance to conceive. This paper reports on two studies that investigated onset of puberty in red deer hinds. In Study 1, ovarian follicle populations and luteal activity of pubertal and adult red deer hinds were monitored for three months during their transition into the breeding season. Yearling (n = 5) and adult (n = 5) hinds were grazed in one group and weighed monthly. A fertile stag was run with them from 20 March until 11 May. Yearling hinds were significantly lighter than adults in March (85.8 vs 91.3 kg, SED = 2.1). There were no significant differences between yearling and adult hinds in mean day of first (14 April vs 8 April, SED = 3.5) or second (23 April vs 16 April, SED = 3.7) ovulations, or interval between ovulations (9 vs 8 days, SED = 0.7). First ovulation was invariably followed by a transient rise in plasma progesterone concentration and then a second ovulation preceded by oestrus. All hinds conceived to their first mating, demonstrating the ability of red deer hinds to exhibit high conception rates. In Study 2, daily observations for mating activity of yearling (n = 80) and adult (n = 80) hinds were carried out continuously from dawn until dusk for the period 25 March-27 April. Hinds were grazed on pasture in one of five single sire mating groups: Gp1, adults only (n = 40); Gp2, yearlings only (n = 40); Gp3, adults (n = 20) + yearlings (n = 20); Gp4, adults (n = 10) + yearlings (n = 10); Gp5, adults (n = 10) + yearlings (n = 10). Hinds were scanned by rectal ultrasonography to determine pregnancy status and estimate fetal age. Yearling hinds were significantly lighter than adults in March (101 vs 119 kg, SED = 1.3). The stag in Gp3 was replaced due to exhaustion and consequently, mean conception date of yearlings in that group was 16 days later than that of the yearlings in Gps 2,4 & 5, which had a mean conception date 12 days later than that of the adults (1 May vs 15 April vs 3 April, SED = 1.1; P < 0.001). There was no significant difference between age groups in the number of non-pregnant hinds. These data indicate that yearling red deer hinds reach puberty and are mated in mid-April, about two weeks later than adult hinds. Conception failure was not a limiting factor to yearling reproductive performance; therefore, under standard farming conditions, it is unlikely that stags will be removed from the mating mob before yearling hinds have had a chance to conceive. KEYWORDS: red deer hinds; puberty; reproduction.

Puberty in red deer hinds : (2) Effects of introducing spiker stags in early January - Scott IC; Ward JF; O'Neill KT; Littlejohn RP (Proceedings of the New Zealand Society of Animal Production, 2005)
Calving date of yearling red deer hinds is, on average, two weeks later than that of adult hinds, further misaligning feed quality with nutritional requirements. The hypothesis that early joining of spiker stags with yearling red deer hinds would increase pregnancy rate and advance date of conception was studied. Yearling hinds (n = 309) were grazed in one group at least 500 m from any stags from the first week in November until 14 January when hinds were weighed, wapiti scored and randomly allocated to either an early stag joining (ES) or control (C) treatment. ES hinds were grazed as one group with 20 spiker stags and C hinds were kept in paddocks well removed from stags. On 2 March, all hinds were weighed again and 20 spiker stags joined with the C hinds. ES and C groups were grazed separately until being combined in mid-April. The stags were removed on 18 May, and hinds ultrasound pregnancy scanned on 1 June. There were no significant differences (P > 0.05) between ES and C treatments in mean wapiti score (1.8 vs 1.8, SED = 0.08), live weight (January: 79.8 vs 79.0 kg, SED = 0.86; March: 86.4 vs 85.8 kg, SED = 0.85), fetal age (48.5 vs 46.8 days, SED = 1.0) or percent hinds pregnant (85.7 vs 88.7 %, SED = 3.5). The probability of hind pregnancy increased significantly with live weight within wapiti score classes and decreased with increasing wapiti score (P<0.01), such that, with mean class live weights of 75, 81, 88 and 95 kg, the expected percentage of pregnant hinds was 95, 91, 88 and 73 % for wapiti scores of 1, 2, 3 and 4+, respectively. Fetal age increased by 0.11 (SEM 0.054) day for every 1 kg increase in January live weight (P < 0.05), but showed no significant relationship with wapiti score. These data indicate that early joining of spiker stags did not significantly improve the pregnancy rate or advance conception date of yearling red deer hinds. KEYWORDS: red deer hinds; puberty; early stag joining.

Re: Relation between sweating and wool yellowing in Merino and Romney sheep - Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 2005)
In the original printed version of this paper, incorrect labelling of some of the axes occurred in two of the figures. Corrected versions are shown below. The authors regret this error.

Regulating milk fat synthesis: potential on-farm applications of basic science - Baumgard LH; Kay JK; Moore CE; Roche JR; Vanbaale MJ; Rhoads RP (Proceedings of the New Zealand Society of Animal Production, 2005)
This review covers results from numerous trials evaluating conjugated linoleic acid (CLA) effects on milk fat synthesis and its potential as an on-farm management tool to improve dairy cow performance. Supplemental CLA reduces milk fat synthesis in numerous animal models, and in grazing dairy cows can improve energy balance as well as increase milk and milk protein yield. Mammary lipid metabolism effects are thus far specific to trans-10, cis-12 CLA, and we demonstrated trans-10, cis-12 CLA reduces mRNA expression of enzymes required for de novo fatty acid synthesis, fatty acid uptake and intracellular transport, and triglyceride formation. The amount of CLA required to reduce milk fat synthesis in lactating cows has little or no effect on circulating basal bioenergetic metabolites and hormones or stimulated responses to homeostatic signals. We hypothesized CLA can be utilized to stimulate milk fat depression when milk synthesis and other physiological processes are limited by energy availability, as is the case in early lactation, during heat stress and occasionally in pasture based dairying. Our research focuses on identifying the mechanisms of action and potential use of CLA as an on-farm management tool to increase farm profit via increased milk production, improved reproduction and decreased metabolic disorders.

Relation between skin structure and wool yellowing in Merino and Romney sheep - Sumner RMW; Craven AJ (Proceedings of the New Zealand Society of Animal Production, 2005)
Five adult Merino and five adult Romney ewes were skin sampled on the back, midside and belly regions of the body following a study measuring the relationship between rate of sweat secretion and wool yellowing under various controlled environmental conditions. Densities of primary follicles, secondary follicles, sweat (sudoriferous) glands and sebaceous glands, as well as dimensions of the sweat and the sebaceous glands were measured. The density of secondary follicles was negatively related to wool yellowing and there was a weaker positive relationship between the density of primary follicles and wool yellowing. Underlying these relationships were associations of measurements suggesting sebaceous gland output restricted wool yellowing while sweat gland output encouraged wool yellowing. In addition, large sweat glands were related to increased sweat secretion rate. The results of this study suggest there may be two potential avenues to minimise fleece discolouration while the wool is growing on the sheep; either increasing sebum production or reducing sweat production. KEYWORDS: Romney; Merino; wool yellowing; wool follicles; sweat glands; sweat; sebaceous glands.

Relationship of mean fibre diameter and time of shearing with wool yellowing in Merino sheep farmed under North Island conditions - Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 2005)
Approximately 200 adult Merino ewes at each of four sites in New Zealand, near Hamilton (Whatawhata), near Rotorua, near Havelock North (Poukawa) and near Wanganui were shorn once-yearly at five different times over two years. Groups of approximately 40 ewes in each flock were shorn pre mating (March), post mating (May), pre lambing (July) with lambs-at-foot (October) or at weaning (December/January). Midside fleece samples were collected before shearing for measurement of fibre diameter. At shearing each fleece was weighed and skirted. The skirted fleece and skirtings were weighed and core bored for measurement of wool yellowness. The between flock and between shearing time ranking for increasing wool yellowness was Wanganui, Poukawa, Rotorua, Whatawhata and lambs-at-foot, pre lambing, weaning and post mating, pre mating respectively for both the unskirted and skirted fleeces. There was a significant positive relationship between mean fibre diameter and wool yellowing with no difference in the slope of the relationship between flocks or between shearing time treatments. These trends align with finer-woolled Merino sheep having more sebaceous glands, the secretion from which appeared to protect growing wool fibres from the action of components in sweat secreted in response to warm moist atmospheric conditions. The optimal shearing time to produce the whitest wool was spring. KEYWORDS: Merino; wool yellowing; fibre diameter; shearing time.

Relationships among metabolic hormones, luteinising hormone and anoestrus in periparturient dairy heifers fed two nutritional levels prepartum - Pleasants AB; Chagas LM; Burke CR; Smith JF; Soboleva TK; Peterson AJ (Proceedings of the New Zealand Society of Animal Production, 2005)
A mathematical model that describes the dynamics of reproductive hormones was developed to estimate the duration of the postpartum anoestrus interval (PPAI) in cows. The model identified two relatively separate mechanisms: one influenced PPAI through luteinising hormone (LH) release; and it is suggested that another one controlled ovary sensitivity to LH. Examining the role played by these mechanisms in the relationships between nutrition and PPAI involved analysing the data from an experiment that measured the effects of prepartum nutrition on PPAI in which levels of insulin-like growth factor-I (IGF-I), insulin, glucose, leptin and growth hormone (GH) were recorded. Five months before calving, 30 Holstein-Friesian heifers were randomly allocated to a high (HP) or low plane (LP) of nutrition. Body condition scores at calving were 6.3 and 4.1 for the HP and LP treatments respectively. Both groups were fed ad libitum after calving. Secretion patterns of LH were measured at 2, 5 and 8 weeks after calving. PPAI differed between treatments (HP 62.0 ± 7.95 days; LP 83.1 ± 6.95 days; P < 0.05), as did the level of GH at calving (HP 5.8 ± 1.23 ng/ml; LP 10.3 ± 1.23 ng/ml; P < 0.001). The within treatment variation in PPAI was partitioned into that associated with LH frequency post calving and that orthogonal to LH pulse frequency. Within each treatment, GH was associated with the LH frequency and insulin was associated with the component orthogonal to LH frequency. These results link nutrition to the PPAI through the dynamics of insulin and GH. KEYWORDS: mathematical model; anoestrus; dairy cows; nutrition; metabolites; LH.

Relationships between milk yield, milk composition and electrical conductivity in dairy cattle - Yoshida T; Lopez-Villalobos N; Holmes CW (Proceedings of the New Zealand Society of Animal Production, 2005)
The purpose of this study was to investigate the relationships between electrical conductivity (EC) and milk yield and composition in Japanese dairy cattle. In total, 4380 quarters of 106 cows were used in this study. Individual cows were herd tested in the evening with a quarter-milker fortnightly on at least 6 occasions during the lactation. Herd test records were collected from 1990 to 1998. Each quarter was sampled for milk yield, concentrations of fat, protein, lactose and solids-not-fat (SNF) and EC. Each milk quarter sample was classified into one of 9 classes of EC value and one of 10 classes of quarter difference EC value (QdEC). The QdEC for each quarter was calculated as the difference between the EC value for that quarter and the EC value of the quarter with the lowest value within the same cow, on a given herd-test day. Statistical analyses were performed using a mixed linear model for repeated measures considering the fixed effects of quarter position, lactation stage and their interaction, parity, calving season and the EC or QdEC class, and random effects of cow and quarter within cow. Previous studies have recommended criteria for healthy quarters of < 6.3 mS/cm for EC and < 0.3 mS/cm for QdEC. In the present study, quarters with values above these criteria did have significantly lower milk yields (by 15 to 20%), but these decreases became apparent above values for EC and QdEC of 5.4 mS/cm and 0.2 mS/cm respectively, much lower than the suggested criteria. Milk yield was reduced by approximately 2% for every 0.1 mS/cm increase in the QdEC. The higher value classes for EC, and for QdEC both showed significantly lower concentrations of fat, lactose and SNF (P < 0.05). In the present study, decreases in milk yield and concentration of fat and lactose occurred in quarters that would have been considered to be normal by the previously accepted criteria for EC and QdEC. KEYWORDS: electrical conductivity; milk yield; milk composition.

Relationships between on-farm and pre-slaughter behaviour and growth and meat quality for bulls and steers - Burnham DL; Purchas RW; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2005)
Angus and Hereford-Angus cross bulls (n = 58) and steers (n = 59) were assessed for temperament 3 times during post-weaning growth and for behaviour during pre-slaughter holding in order to investigate relationships between these traits and measures of growth and meat quality including meat tenderness and meat colour. Composite on-farm temperament scores encompassed measures during weighing of stepping and unease on the scale, and speed of movement and level of agitation when released from the scale. Pre-slaughter assessments included counts of butting, pushing, fighting and mounting. Plasma levels of cortisol, glucose, lactate and fatty acids at slaughter were measured. On-farm temperament scores were significantly correlated (P < 0.0001) between the 3 times and between measures within a time. On-farm measures, however, were not related to pre-slaughter scores or to plasma cortisol or metabolite levels. Plasma cortisol levels were significantly higher for steers than bulls (43.8 vs 22.4 ng/ml; P < 0.001) as reported previously, and bulls had significantly higher pre-slaughter behaviour scores, but there were no castration effects on levels of plasma metabolites or on-farm temperament scores. Relationships between behavioural traits and measures of growth rate and meat quality based on treatment-adjusted residuals were low and non-significant. It is concluded that despite on-farm temperament scores being moderately repeatable, these measures were not associated with differences in pre-slaughter behaviour, and neither of these traits was associated with growth rate or measures of meat quality. KEYWORDS: animal behaviour; meat quality; meat pH; cortisol; growth rate; tenderness.

Repeatability of fatty acid composition in pm:am milk samples from cows - Morris CA; Hickey SM; Agnew MP (Proceedings of the New Zealand Society of Animal Production, 2005)
The present study was designed to estimate the repeatability of fatty acid composition in cows’ milk collected at a pm:am herd test. As part of a larger project, whole milk was collected during a routine herd test in March 2003 from 10 Friesian and 10 Jersey cows at Flock House, in the evening and again the following morning. Fat in the 40 samples was separated by centrifugation, fatty acids were converted to their methyl esters, and individual fatty acid percentages in each sample were assayed by gas chromatography. In general, the fatty acid composition of milk was very similar at the pm and am samplings. For the fatty acids making the largest contributions (10 to 29% of the total) to fatty acids present in milk (C14:0, C16:0, C18:0 and C18:1 cis-9 (oleic)) and for conjugated linoleic acid and the Mono- Unsaturated/Saturated ratio, pooled within-breed correlations of compositions between pm and am milk samples were high (0.76, 0.80, 0.88, 0.76, 0.75 and 0.74, respectively; standard errors 0.06 to 0.12). The pm:am correlation, averaged over the most abundant 15 fatty acids in milk, was 0.77 ± 0.10. It is concluded that a single milk sample or a pooled pm:am sample is adequate for estimating the composition of the predominant fatty acids. KEYWORDS: milk; fatty acid; cows; repeatability.

Research support for new uses and improved production of deer velvet - Suttie JM; Haines SR; Clark DE; Archer JA; O'Connor M; Broeder CE; Corson ID (Proceedings of the New Zealand Society of Animal Production, 2005)
Deer velvet is a novel agricultural product and has presented the New Zealand (NZ) agricultural and food sectors with a number of opportunities. When the velvet industry emerged in the early 1970s, almost the entire product was exported to the traditional oriental medicine markets, which remain the basis of the deer velvet industry in NZ. This market did not require scientific validation of efficacy as the health promoting effects of velvet were accepted. However, as this is a mature market there is interest in growing new business, notably the Western dietary supplement market. This requires new knowledge on health benefits as potential purchasers have no initial product knowledge. We have conducted research to investigate whether or not deer velvet will help promote health. We chose to look for a verifiable benefit to athletes as the athletic market would be less likely to be price sensitive than other sectors. We also investigated the application of specific velvet extracts as topical agents to promote healing of open wounds, based on their ability to promote the growth of blood vessels (angiogenesis). This paper discusses the research that set out to demonstrate velvet efficacy and quality and describes research on nutrition and breeding designed to increase velvet quality and quantity. KEYWORDS: deer; velvet; antlers; production; quality; wound healing; dietary supplement; health benefits.

The role of suckling on the parasite status of very young lambs infected with Teladorsagia circumcincta - Iposu SO; Greer AW; McAnulty RW; Stankiewicz M; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 2005)
This study investigated the importance of suckling for the resistance and/or resilience of very young lambs to Teladorsagia circumcincta nematode infection. Thirty, 6-week old twin-born lambs were allocated to four treatment groups in a 2 x 2 factorial design in which groups continued to suckle (S-) or were weaned (W-), and concurrently not infected (-N) or infected (-I) with 1000 L3 larvae of T. circumcincta per day while grazing ‘clean’ pasture for six weeks, and then slaughtered. There was a significant infection by time interaction on faecal egg counts (FEC; P < 0.001). Suckling/weaning had no effect on FEC. Worm burdens were similar in suckled-infected (SI) and weaned-infected (WI) lambs (8029 + 1502 vs 12228 + 1704 worms, SEM; P > 0.05), respectively. Eggs per utero were significantly greater (29 + 6 vs 15 + 1 eggs, SEM; P < 0.05) in SI than WI lambs, while length of female worms was similar in both groups (10.2 + 0.2 vs 9.7+0.3mm, SEM; P > 0.05), respectively. The two suckled groups progressively gained more weight (P<0.001), while uninfected lambs of both groups were heavier (P < 0.05) from day 28 onwards. Weight gain averaged 122, 282, 98, and 240g day-1 for the WN, SN, WI, and SI lambs, respectively. The study has not shown any advantage of suckling while grazing for lambs’ resistance or resilience to larval intake within the 12-week post lambing period. KEYWORDS: Teladorsagia circumcincta; suckled lambs; resistance; resilience.

Sire-line differences in lamb losses from starvation exposure - Gudex BW; Hickford JGH; Frampton CM (Proceedings of the New Zealand Society of Animal Production, 2005)
Sire-line differences in neonatal lamb mortality due to starvation-exposure (diagnosed using basic ‘on farm’ observations) were observed in five trials (1390 lambs in 15 sire-groups). After correcting for variations in lamb birth weight and in the cold challenge experienced by each lamb using logistic regression, sire-line differences in lamb mortality due to starvation-exposure were detected in flocks where the cold challenge and the number of progeny in each sire line was sufficient (P < 0.05). Although sire-line differences in lamb mortality due to starvation-exposure were detected independent of birth weight, the analyses revealed that birth weight is still the largest influence upon lamb mortality due to cold exposure (P < 0.05). These results confirm that due to the large and contradictory role that birth weight has in influencing lamb survival, it is extremely important to record and account for it in any attempt to breed for enhanced lamb survival. The detection of sire-line differences in lamb mortality due to starvation-exposure independent of birth weight could provide a basis to select for improving lamb survival, thus raising the efficiency of lamb production.

Software for evaluating sampling strategies and error rates in the identification of mixed meat products - Vetharaniam I; Shackell GH (Proceedings of the New Zealand Society of Animal Production, 2005)
DNA verification of the origin of meat within traceability systems involves the comparison of DNA samples taken at a reference stage with samples taken further down the supply chain. While such verification is well established when whole cuts of meat are involved, this is not the case for mixed-meat products made from an unknown number of contributing animals. Spreadsheet based software has been developed to analyse one DNA verification scheme for determining whether a returned product did indeed originate from a particular manufacturing batch. The scheme involves the comparison of k individual DNA samples (comprising an unknown number of individuals) from the product, with a set of s DNA samples (comprising an unknown number of individuals) taken randomly before manufacture of the batch in question. The software gives the error rate for correctly matching the product to the batch, for different sampling rate combinations of the product and at the factory. Key words: DNA verification; mixed meat; traceability; sampling.

A study of mastitis in two small experimental dairy herds managed either organically or conventionally during one year - Silva KE; Quinn AK; Morel PCH; Holmes CW; Thatcher A; Shadbolt NM; Kelly T (Proceedings of the New Zealand Society of Animal Production, 2005)
Mastitis infection status of two small herds located at the Dairy Cattle Research Unit of Massey University was assessed. Single quarter milk samples from 45 cows under organic production (first and second year of organic certification) and 50 cows under a conventional system were taken on four occasions: mid lactation (these samples were frozen); prior to the last milking before dry-off (season 2003/2004); before the first milking after calving and 14 days post calving (season 2004/2005). Milk samples were cultured for bacterial analysis. Somatic cell counts (SCC) from monthly herd tests, and clinical mastitis cases were recorded and analyzed. The percentages of quarters with positive bacterial growth, and SCC, were generally higher in the organic herd, but differences were only significant for Staphylococcus aureus in all four sample periods, and for Streptococcus spp. 14 days post calving. The results suggest that in organic herds Staphylococcus aureus infections could become an important concern, because of constraints on the use of antibiotic treatments. Effective prevention of infections by this organism will be essential, in order to prevent high culling rates. KEYWORDS: mastitis; organic dairy; New Zealand.

A survey of the control and financial impact of footrot in the New Zealand Merino industry - Hickford JGH; Davies S; Zhou H; Gudex BW (Proceedings of the New Zealand Society of Animal Production, 2005)
A survey was sent to 869 Merino farmers in New Zealand in August 2001 seeking information about the prevalence of footrot, treatment and control measures applied, their related costs, and estimated production losses attributable to the disease. There were 304 respondents to the survey and they farm approximately 43% of the Merino sheep in New Zealand. Footrot was reported to be present in 59% of the respondents’ flocks with 6.4% of the sheep infected by footrot at the time of surveying. Foot bathing, culling of affected sheep and breeding for footrot resistance in flocks were the preferred control measures. Footrot treatment was calculated to cost $1.67 per Merino sheep per year with an additional $1.77 per sheep attributed to losses in animal production. Assuming the respondents are representative of the New Zealand Merino industry, the total cost of footrot to this industry was estimated to be in excess of $11 million annually.

Traceability around the world - Nortje GL (Proceedings of the New Zealand Society of Animal Production, 2005)
With the business case for a national animal identification system due in July 2005, it is appropriate to take stock and to see where New Zealand (NZ) and other countries are at with animal and full supply chain traceability. The objective should be to learn and contribute to the outcome. Full supply chain traceability is on the horizon, NZ needs to be proactive and valuable lessons are available particularly from the United Kingdom (UK) and Canadian experiences. The preferred position seems to be one where government plays a leading role without burdening the industry with yet another set of legislative requirements. For this to work effectively, the industry has to commit to traceability, to go beyond ordinary compliance type applications and to use it as a differentiator in the market place. Traceability is not going to go away, and as the requirements will continue to increase around the world, the best option is to embrace it.

Traceability contract session: Introduction - Shackell GH (Proceedings of the New Zealand Society of Animal Production, 2005)
Food safety issues, especially those associated with animal disease (e.g. BSE in cattle), human health (e.g. salmonellosis), genetic modification and animal welfare are driving consumer pressure for traceability of animal-derived foodstuffs. Several of our trading partners already have in place, or have signalled, expected compliance dates for meat traceability requirements. This contract session addresses some of the background as to why, and when, New Zealand (NZ) can expect to be required to have traceability procedures in place to ensure continued access to the world`s meat and animal derived foodstuffs market. The following 10 papers will also describe examples of what is currently in place or projected to become available for tracing animals on the farm, during transport and through meat processing plants both in NZ and overseas. The mix of speakers has been chosen to encompass legislative, industry and scientific aspects of traceability of meat and meat products.

Traceability databases in the New Zealand sheep industry - Cruickshank CJ (Proceedings of the New Zealand Society of Animal Production, 2005)
Sheep traceability will become a necessity in New Zealand to cover consumer, biosecurity and international trade requirements. The requirement to track individual sheep from lamb processors to the farm of birth is a major logistical challenge but is considerably easier than in some of New Zealand’s trading partners. Definition of the requirements of a traceability system and implementation into an effective model are still under debate. A major requirement is the design and implementation of a central database to cater for present and future needs. A traceability system could be developed using databases and technology already used in the sheep industry.

Traceability systems in the meat industry - Shackell GH (Proceedings of the New Zealand Society of Animal Production, 2005)
New Zealand is reliant upon maintaining export markets for the sale of a significant proportion of its meat and dairy production. Any loss of key overseas markets has significant implications for the national economy. Therefore, we are obliged to meet or stay ahead of market drivers. Increasingly, one of those drivers is product traceability for reasons of consumer confidence. While traceability systems have a relatively short history, they have traditionally been paper and/or electronic based. They are generally managed by parties with a vested interest, and their integrity is difficult to monitor. Animal products have a unique identifier, DNA, that is tamper proof. There are a number of DNA-based traceability systems around the world that are being used in the meat industry. As well as direct tracing of a meat sample back to the animal, and ultimately to the property the animal was raised on, DNA technologies are also being used on-farm for testing meat quality traits and determining the animal’s pedigree. This paper describes some of the traceability options that are in use within the environment in which New Zealand is competing for trade. KEYWORDS: traceability; meat; DNA.