Water intake of red deer stags consuming dryland pasture or indoors on concentrated feeds - Barrell GK; Topp DF (Proceedings of the New Zealand Society of Animal Production, 1989)
Exogenous melatonin has been demonstrated to induce early winter furring in farmed mink and fox. In an exploratory trial implants containing either 0, 4, 8, 12 or 18 mg of melatonin (Regulin. Ltd, Melbourne) were inserted subcutaneously in nine groups of ferrets (farmed fitch). The treated groups each consisted of 12 male and 12 female fitch. Forty four untreated fitch comprised the controls. The implants were administered either in mid-January to 8-week old kits or in mid-February to 12-week old kits. At 14-day intervals, all animals were weighed and the 24 hour dry matter consumption of 3 groups (with 0, 8 and 18 mg melatonin implants) measured. All pelts were graded for size, clarity, quality and colour. The melatonin implants caused a significant increase in feed consumption two weeks after administration accompanied by an increase in weight gains. Appetite and weight gains subsequently increased in untreated fitch and weights at pelting were not significantly different between treated and untreated fitch. Melatonin administered in January caused an early, but limited, development of the winter fur pelage. Many of these animals subsequently developed a new winter coat and pelting time was later than for untreated controls. The February treatment caused an advancement in pelt prime by up to 6 weeks compared with control animals (19 April v 1 June). Quality and size attributes of pelts from treated fitch were comparable to control animals. Differences between the various experimental formulations in their ability to maintain high levels of plasma melatonin for long periods was associated with the occurrence of premature moult in some groups. These data indicate that an optimum melatonin treatment strategy has a role on fitch farms in inducing an early pelt prime with savings in feed and labour and increased management control over pelt processing but that suboptimum treatments are contraindicated for this application.

Advancement of the breeding season in Coopworth ewes - Smith JF; McGowan LT; Knight TW; MacLean KS (Proceedings of the New Zealand Society of Animal Production, 1988)
In 1986 the ovulation rates of 21 Romney ewes selected for facial eczema (FE) resistance (R) and 27 selected for FE susceptibility (S) were recorded on day 5 of the cycle following synchronisation of oestrus with controlled internal drug releasers (CIDR) at the end of April. The ewes were then all dosed daily with 10ml of slurry of a culture of Fasarium containing 6mg zearalenone for 10 d. The ewes were re-examined for post-treatment ovulation rate. The resistant ewes had a higher ovulation rate pre-treatment than did the susceptible ewes (R=1.90 and S=1.50). Both groups showed a decline in ovulation rate after zearalenone treatment (R=1.35 and S=1.22). In 1987 Romney ewes from 4 FE resistance selection flocks (Model resistant (MR) n=148; Model control (MC), n=105; Resistant (R), n=110 and Susceptible (S), n=73) were examined by laparoscopy at the beginning of April. The ovulation rates were higher in the resistant flocks (MR = 1.73; MC = 1.55; R = 1.55; R = 1.42 and S = 1.29). These data indicate that the higher reproductive performance of FE resistant ewes could in part be due to their higher ovulation rates but that resistance to FE confers no protection against the effects of zearalenone.

Animal productivity and the veterinarian: another perspective - Fielden ED (Proceedings of the New Zealand Society of Animal Production, 1988)
Two experiments, involving a total 78 Southdown rams from high- and low- backfat lines, were carried out to examine the relationship between subcutaneous fat percent of a rack cut and subcutaneous fat percent of the whole carcass side. A simple regression was as effective as multiple regressions for 30 carcasses (Group 1), but for each equation there was a significant selection-line effect on the intercept. When the usual direct regression coefficient was replaced by an inverse or a geometric co- efficient, the selection line effect was not significant. The 3 prediction equations were evaluated by comparing predicted side subcutaneous fat percent with actual values for a separate lot of 48 ram carcasses (Group 2). The correlation between predicted and actual values was high, but the selection-line effect was significant for all 3 equations. These results serve to emphasis that even within a breed and sex, and for relations with high correlations, there may be problems with the stability of the prediction equations. This could introduce a bias into conclusions.

Calf weaning and summer grazing strategies for efficient beef cow use on hill country - McCall DG; Scott ML; Dow BW (Proceedings of the New Zealand Society of Animal Production, 1988)
No abstract supplied

Carcass composition of exotic sheep breeds - Clarke JN; Parratt AC; Malthus IC; Amyes NC; Uljee AE; Woods EG (Proceedings of the New Zealand Society of Animal Production, 1988)

Cervical versus laparoscopic AI of goats after PMSG injection at or 48 hours before CIDR removal - Moore RW; Miller CM; Hall DRH; Dow BW (Proceedings of the New Zealand Society of Animal Production, 1988)
An experiment was conducted in which 1402 Romney ewes, aged 2 to 5 years, were treated with intravaginal controlled internal drug releasers (CIDR) followed by 1 of 2 pregnant mares serum gonadotrophin (PMSG) preparations (Pregnecol(r), 530 iu v Pharmochem(r), 460 iu) for mating on 1 of 3 dates (December 19, 28 or January 3). Of the 1402 ewes joined with the ram, 71% conceived to the first cycle. Conception rates, proportion of ewes conceiving multiples and foetuses per ewe joined were assessed by ultrasound pregnancy diagnosis at day 50 of pregnancy. Reproductive performance was highest in 2-year old ewes but not influenced by previous reproductive history (wet v wet/dry in the previous spring). All measures of reproductive performance declined at later mating dates compared with those at December 19. Substantial premiums were obtained for early-born lambs, and for their dams when slaughtered at weaning the following September. Out-of-season lambing systems appear to offer economic benefits in areas characterised by good winter and spring growth rates but dry summers.

Comparative performance and energy metabolism of Jerseys and Friesians in early-mid lactation - L'Huillier PJ; Parr CR; Bryant AM (Proceedings of the New Zealand Society of Animal Production, 1988)
The intake, apparent absorption, availability and retention of Se, Cu, Zn and Fe were measured in young lambs using nutritional balance and comparative slaughter techniques. Balances were carried out when the lambs were aged 5 to 11 d, 21 to 28 d, 63 to 70 d and 92 to 98 d. During the first and second balance periods the lambs were fed 175 and 300 g dry matter (DM)/d as milk replacer. In balance 3, 210 g DM/d as milk replacer was fed with fresh pasture ad libitum and during balance 4, only fresh pasture was fed ad libitum. The mean liveweight gain was 250 g/d. The fractions of the ingested mineral which were apparently absorbed on the milk replacer diet were Se 0.95, Cu 0.92, Zn 0.62 and Fe 0.50. These progressively decreased to Se 0.45, Cu 0.10, Zn 0.16 and Fe 0.20 for the all pasture diet. From the comparative slaughter study it was found that 44

A comparison of ultrasound backfat measurements on sheep - Nicol AM; Jay NP; Beatson PR (Proceedings of the New Zealand Society of Animal Production, 1988)
Mating records from Dairy Board files for 1984 were analysed. First inseminations with liquid semen were considered, and the effect of several factors on conception analysed. Conception was scored as 1 if a calving occurred 272 to 293d after insemination, and 0 if a calving occurred outside that interval. Only records from animals with a known calving date were included. The data were analysed by linear model techniques, with conception as a dependent variable. The factors contributing to variation in conception were (in order of declining importance): herd, technician, post-partum interval, service sire and age of cow. The R2 was 0.072 indicating that most of the variation is caused by binomial error.

Components of foam and liquor from the rumen of bloating and non-bloating cows - Waghorn GC (Proceedings of the New Zealand Society of Animal Production, 1988)
There is strong evidence that growth hormone (GH) does not enhance lactation through a direct effect on the udder but rather that the effect is mediated by insulin-like growth factors (IGF) -I an/or IGF-II produced by the liver. While plasma IGF-I concentrations rose following GH injection of dairy cows and goats, intravenous infusion of goats with IGF-I did not increase milk yield. However, GH treatment increased the relative binding of IGF-I to a high molecular weight binding protein in plasma. Plasma binding proteins may crucially affect the transport of IGF's from plasma to tissues. Plasma IGF-II concentrations doubled during GH treatment of lactating goats. In view of the increased presence of IGF-II receptors in mammary tissue during lactation it is possible that plasma IGF-II is involved in mediation of the GH effect on lactation. The increased partition of nutrients for milk synthesis achieved during GH treatment is facilitated by increased blood flow to the udder. There is little change in the plasma concentration of substrates for milk synthesis. It is likely that the increased blood flow occurs as a metabolic consequence of increased milk synthesis.

DairyMAN: A Massey University animal management program - McKay BJ (Proceedings of the New Zealand Society of Animal Production, 1988)
Most cows fed fresh forages containing clover or lucerne have a foamy rumen digesta. When the foam becomes persistent (stable), gasses from fermentation become trapped and the cow bloats. Samples of foam and rumen liquor from bloated and non-bloated cows fed freshly cut lucerne or red clover were analysed to determine differences that may account of foam stability. In a bloated cow the density of rumen digesta falls from about 950 to 600 or 700 g/l and the foam has a density of 200 to 300 g/l. Analysis of foams showed no difference between bloat and non-bloat samples in dry matter (DM)(7.8%) nitrogen (94 mg/g DM) or chlorophyll (7.4 mg/g DM), but bloat foams had a higher lipid concentration (57 mg/g DM) than non- bloat foams (40 x 10 7/gDM). The significance of these observations are discussed in relation to foam stability.

Detecting inherited variation in DNA sequences and its application in animal science - Montgomery GW; Hughes G; Hill DF (Proceedings of the New Zealand Society of Animal Production, 1988)
A high fleece weight Romney ewe flock was established by selecting the top 0.6% on greasy weight (GFW) from 32,000 hoggets (average selection differential 40%). These ewes were mated in 1985 and 1986 by Romney rams with high positive deviations for GFW (selection differentials 48% in 1985 and 57% in 1986). Relative to random progeny, the high fleece weight progeny born in 1985 and 1986 had 0.66 kg (28%) and 0.36 (12%) higher mean GFWs, respectively. Estimates of realised heritability were 0.45 and 0.22 for the 1985 and 1986 born hoggets, respectively. Two sires used in 1985 had progeny distributions for GFW consistent with their having 1 copy of a single gene for GFW with an additive effect of approximately 1 kg. The single gene hypothesis is being examined by further progeny testing. From birth to hogget shearing the high fleece weight hoggets had a significantly higher live weight than the control hoggets. Fleeces from the high fleece weight and control hoggets did not differ in yield or brightness. The high fleece weight hoggets had greater staple length, fibre diameter and staple strength with lower bulk and greater yellowness. Estimates of the heritability of live weight, fleece weight and wool characteristics agreed with published estimates, as did estimated genetic correlations between GFW and other characteristics. The heritability of brightness was low.

Development of a dried colostrum - Donnelly PE; Petch SF; McLaren RD; Oakley AP (Proceedings of the New Zealand Society of Animal Production, 1988)
Inherited protein variation in the blood of domestic species can provide the means to resolve cases of uncertain parentage. In red deer, protein variation has been described from natural populations in Europe, although the inheritance of this variation has not been verified using family data. This paper examines protein variation in the blood of New Zealand farmed red deer and tests the inheritance of each protein variant using family data from 46 matings. The 2 most variable proteins reported in European deer, transferrin and isocitrate dehydrogenase, were also variable in New Zealand farmed deer. The inheritance of variation in each of these proteins was consistent with co-dominant Mendelian inheritance at a single locus. In addition variation was found in plasma proteins in the postalbumins and the gamma-globulins. Variation in the postalbumins was consistent with co- dominant Mendelian inheritance at a single locus while variation in the gamma-globulins did not appear to be inherited. The inherited protein variants identified in red deer provide a blood test which detected 70% of the possible mismatches between parents and calves in the sample of 46 matings.

The development of an autumn lambing flock of Dorset x Romney ewes without the use of hormones - McQueen IPM; Reid TC (Proceedings of the New Zealand Society of Animal Production, 1988)
Aspects of seasonal physiology were monitored in red deer either untreated or treated with melatonin designed to advance the onset of the natural breeding season. Treated animals were implanted with melatonin at monthly intervals during December, January and February (adult stags and yearling hinds) or January and February (lactating hinds). Rutting behaviour, antler casting and velvet antler regrowth occurred up to 2 months earlier in melatonin-treated stags, while mean calving dates were advanced by 11 d in both groups of treated hinds. In yearling hinds, melatonin treatment advanced by about 1 month the phase of low growth which occurred in control hinds in autumn. However, treatment had little overall effect on live weight of yearling hinds or lactating hinds. Treated hinds moulted their red summer coats and grew lighter winter-like coats about 1 month earlier than untreated hinds. The growth rates of calves sucking melatonin-treated and untreated hinds were virtually identical. These results indicate that melatonin treatment can advance several aspects of seasonal physiology in deer.

Development of systems for out-of-season lambing at Limestone Downs - Lowe KI; Carter ML; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1988)
DairyMAN is a computerised dairy herd health and management program recently developed within the Department of Veterinary Clinical Services at Massey University. The program is designed to be a reproduction, health and production recording and analysis system for use on either annual or twice yearly seasonal calving dairy herds. It is intended that the program be used as a management aid for farmers, veterinarians and farm advisors. DairyMAN is able to accept data from a variety of different collection methods, for example the Livestock Improvement Division (LID) notebook, shed sheets, wall charts, mating wheels or formal diary systems. On most farms the current recording system needs minimal modification to accommodate the program. The type of information that may be entered into DairyMAN includes farm, herd and individual cow data. From these data the following reports may be generated: 1. Performance indicators 2. Diagnostic indicators 3. Management aids 4. Simple information collation The program is an example of the development of computer management aids which quickly and effectively analyse herd and farm performance and can target problem areas that need attention. The level of utilization of the program for a single farm will vary depending on the demands of the farmer, his advisor and his veterinarian. Their combined enthusiasm in the farm activities will encourage increased usage of this management aid.

Early growth and reproduction of exotic sheep breeds - a preliminary report - McMillan WH; Malthus IC; Clarke JN; Amyes NC (Proceedings of the New Zealand Society of Animal Production, 1988)

Effect of nutrition on the ovulatory response of Coopworth ewes to varying doses of two FSH preparations - Thompson JGE; Smith JF (Proceedings of the New Zealand Society of Animal Production, 1988)
The effects of Regulin melatonin implants and type G progesterone impregnated controlled internal drug releasers (CIDR) on the early breeding of F+ and ++ Booroola x Perendale and Waihora Romney ewes were compared in a 2 x 2 factorial trial, melatonin v no melatonin x progesterone. The melatonin plus progesterone and melatonin only groups were implanted with melatonin on 12 December and 23 December respectively. While CIDRs were inserted on 7 January and removed on 19 January, when fertile rams were joined with all treatments. Progesterone alone induced oestrus and ovulations 2 to 9 d after ram introduction in 39%, 50% and 11% of F+, ++ and Romney ewes, whereas progesterone plus melatonin induced oestrus and ovulations in 68%, 76% and 44% of the ewes respectively. There was no response to treatment in terms of percentage ewes lambing. The response to treatment in terms of the percentage of lambing ewes with multiples was different in the 3 genotypes. There was no response to either melatonin or progesterone by the F+ ewes, whereas the ++ ewes responded to both additively, leading to a difference of 50% between melatonin plus progesterone and the control groups. The Romney ewes responded only to melatonin leading to an overall melatonin response of 21%.

Effect of shearing once-yearly in October or twice-yearly in February and October on ewe performance - Sumner RMW; Willoughby LD (Proceedings of the New Zealand Society of Animal Production, 1988)
No abstract supplied

Effectiveness of drenching Saanen milking does - Watson TG; Hosking BC (Proceedings of the New Zealand Society of Animal Production, 1988)
The trial reported in this paper was undertaken to determine the potential of using multivariate analyses of blood metabolites to indirectly select for fleece weight. Blood samples from 41 Corriedale rams were analysed for 14 metabolites. A canonical discriminant function of creatinine, urea, magnesium and copper correctly classified 90% of the cull sheep (on the basis of greasy fleece weight). While limitations to the interpretation of this trial are acknowledged, further work appears warranted, as the cost of analysing the blood metabolites is substantially cheaper than other proposed methods such as gene probes, or electrophoresis protein patterns to select for fleece weight at an early age.

The effects of disease on productivity and profitability of livestock: How should it be assessed? - Morris RS (Proceedings of the New Zealand Society of Animal Production, 1988)
Selection for and against susceptibility to bloat in herds of Friesian-Jersey crossbred cattle at Ruakura has resulted in cattle of high (HS) and low (LS) susceptibility. Forty one HS and 41 LS animals including 44 cows and 38 bulls were slaughtered between 1985 and 1987 and weights of carcass components and some body organs measured. LS animals had a significantly higher proportion of bone weight and lower eye muscle area, proportions of hindquarter weight and saleable meat in the carcass than did HS animals. This was offset by a 14% heavier hot carcass weight (HCW) in LS animals. Weights of heart and kidney, adjusted for HCW, were higher and those of mandibular glands were lower, for LS than HS animals. There were no differences between HS and LS herds in adjusted weights of liver, lungs and parotid glands.

Effects of melatonin on early breeding of F+ and ++ Booroola x Perendale and Romney ewes - Moore RW; Miller CM; Dow BW; Staples LD (Proceedings of the New Zealand Society of Animal Production, 1988)
Glenbrae and Broomfield strains of Corriedale sheep were developed over a period of 19 years by selectively breeding from animals that remained free from clinical footrot when deliberately exposed to natural infection. Recent studies have demonstrated relative advantages in these bloodlines during footrot outbreaks in terms of significantly reduced incidence and severity of infection compared to unselected Corriedales. Similar benefits have also occurred in commercial flocks when first cross offspring of Glenbrae and Broomfield rams were compared to offspring of traditional rams. Introduction to the industry of these apparent genetic gains in footrot resistance has been through 2 approaches. Firstly the Broomfield Corriedale Group Breeding Scheme was established in 1982 with 1420 Sheeplan ewes recorded in 5 flocks screened from an estimated 28,000 ewes. The objective is to breed rams for commercial use utilizing performance records and a footrot challenge prior to selection as 2- tooths. Secondly the Corriedale Sheep Society initiated a top-crossing programme mating 3 Glenbrae footrot resistant rams to 81 registered Corriedale ewes in 1986. Details of these 2 approaches are given.

Effects of melatonin on seasonal physiology of red deer - Fisher MW; Fennessy PF; Milne JD (Proceedings of the New Zealand Society of Animal Production, 1988)
The effects of various storage/drying procedures of bovine colostrum on the absorption of bovine serum immunoglobulin (Ig) by neonatal kids was examined. Kids either suckled their dams at birth (control) or were fed warmed liquid bovine colostrum which had been either frozen/thawed, frozen/freeze dried or spray dried. After 4 d on treatment protein analysis showed Ig of bovine origin to be present in the serum of all kids fed bovine colostrum. Kid growth and health were good, and did not differ between treatments. Results suggest that the spray process will provide a dried product with the biological properties of unprocessed colostrum.

Effects of oestradiol on skeletal growth in lambs - Mahgoub O; Barrell GK; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1988)
Growth and hogget reproduction were recorded in Texel, Oxford Down (Oxford) and Finnish Landrace (Finn) purebreds and crosses born in 1985, 1986 and 1987. Border Leicester and Suffolk cross hoggets were included in 1986 and Suffolk cross, Coopworth and Perendale hoggets in 1987. Amongst the purebreds, Oxfords were heavier at weaning than Texels and Finns (100: 92: 89), and as yearlings (100: 93: 88). Amongst the crossbreds born in 1986, Oxfords were heaviest at weaning with Texel, Border Leicester and Suffolks intermediate and Finn crosses the lightest (100: 97: 96: 95: 92). The yearling weight rankings for these 5 crosses were 100: 98: 94: 93: 88. Following entire joining in May after treatment with progesterone impregnated controlled internal drug releasers and pregnant mare serum gonadotrophin, the number of lambs born per hogget joined were, for 1985 and 1986 born purebreds, 1.40 and 1.11 in Finns; 0.76 and 0.96 in Texels and 0.21 and 0.51 in Oxfords. Amongst the 1986 born crosses, Finns ranked highest (1.31 lambs per hogget), Border Leicester, Suffolk and Texel crosses were intermediate (0.61 to 0.65) and Oxfords lowest (0.44). These findings highlight the role of Oxfords for early growth rate and Finns for exceptionally high early reproduction rate.

Effects of rate of weight gain and weight loss on the relationship between carcass weight and GR measurements in cryptorchid lambs - Thorrold BS; Kirton AH; Cranshaw LJ; Mercer GJK (Proceedings of the New Zealand Society of Animal Production, 1988)
Purebred Texel and Suffolk sheep have been grazed together at Belclare in Ireland since 1977. The Texel sheep originated from the Netherlands and are of similar origin to those imported into New Zealand. A series of studies have been undertaken to examine the growth and carcass composition of the 2 breeds. Relative to the Suffolk the Texel has an altered growth patter; Texel lambs were 19% heavier at birth than Suffolk lambs after adjustment for non-genetic effects, but by weaning were 8% lighter (29.08 v 31.76 kg) and the difference increased to 11% at 2.4 years of age. The difference between the Purebred Texel and Suffolk weaning weights is approximately double the value that has been reported in large scale crossbreeding trials. Wool production in the Texel was 12 to 22% higher than the Suffolk breed depending on age. Carcass composition data from 2 separate slaughter trials, using ram lambs, show that the purebred Texel has less subcutaneous fat as a proportion of the carcass than the Suffolk with 75 v 112 g/kg for 18.6 kg carcasses in the first trial and 34 v 80 g/kg and 83 v 125 g/kg when killed at 17.3 and 26.1 kg carcass weight in the second trial. When expressed as a percentage these breed differences are approximately double the values observed in crossbreeding trials. The Texel carcasses also had larger L. dorsi areas and less fat in the internal depots. The food efficiency in the Texel breed was better in the 2 experiments where it was measured, with the differences being significant in 1 trial. Breed differences in composition persisted to maturity with adult Texels having only 78, 81 and 90% of the weight of subcutaneous, kidney knob, and channel and omental fat deposits relative to the Suffolk. In vivo ultrasonic measurements distinguished similar changes in carcass composition between the breeds with C, Gr and estimated L. dorsi in purebred Texels being 85, 78 and 111% of Suffolk ewe and ram lambs. The corresponding figures for adult ewes were 79, 83 and 107%. The carcass composition of most sheep breeds are very similar when expressed as a proportion of mature live weight. The data presented suggests that the Texel is atypical having a modified growth curve and retaining its extreme carcass composition even at maturity.

Experiences with artificial insemination in goats - Bowen GM (Proceedings of the New Zealand Society of Animal Production, 1988)
A flock of 350 to 400 Dorset x Romney ewes was split into autumn- and spring-lambing groups in each of 2 years, 1985-86 and 1986- 87. Joining for autumn-lambing commenced at the end of October, with most mating occurring in late November to early December. Mean lambing date in autumn was 20 April in 1986 and 24 April in 1987. Spring- lambing ewes were joined with rams on 11 March 1986 and 1 April 1987. Mean lambing data in spring was 20 August in 1986 and 6 September in 1987. Liveweight loss over lactation in autumn-lambing ewes was greater than in spring-lambing ewes. Liveweight gain prior to joining was rapid for autumn-lambing ewes, enabling them to reach a live weight of >50 kg prior to joining to lamb in autumn the following year. Number of lambs born per ewe lambing was 110% and 118% in autumn, and 146% and 120% in spring for 1986 and 1987 respectively. Survival of autumn-born lambs to weaning was 7 to 9% higher than for spring-born lambs. Lamb growth rates were lower between birth and weaning in autumn- than in spring-born lambs. Autumn-lambing ewes produced up to 0.1 kg more wool than those lambing in spring.

Factors affecting AB conception rates in cattle - Visser A; Shannon P; Wickham BW (Proceedings of the New Zealand Society of Animal Production, 1988)
A flock of 224 Dorset x Romney ewes was converted from September lambing in 1977 to 96% autumn lambing (mean 16 May) in 1983 while increasing flock size by 50%. Although various techniques of oestrous induction through teasing were used, it was considered that simply introducing entire rams at least 1 cycle before successful tupping was required, eventually gave good results. Four autumn lambing the interval between joining and the first known conception of mature ewe was 35 d during the early years, and declined to 5 d in 1983 to 1987. This decline is suggested to be a genetic change. After the capacity for out-of-season breeding had been developed in all ewes (1982 to 1987), ewes lambing in spring, when subsequently mated to lamb in autumn after a 7 month lambing interval, showed only an 8% disadvantage in conception over those mated to lamb in the following spring after a 12 month lambing interval. Changes in the flock were brought about by culling of spring-lambing ewes and selection of replacements primarily from early lambers. From 1980, rams born to early lambing ewes were used and their first offspring lambed in 1982. This appears to have had a marked effect on 2-tooth lambing times.

Farm factors that influence the eating qualities of lamb meat - Bray AR (Proceedings of the New Zealand Society of Animal Production, 1988)
Alternative methods of using an ultrasonic backfat probe on sheep were compared in 2 experiments involving 60 rams. In both experiments, ultrasonic backfat measurements made on the side of the sheep opposite to the location of the operator and the second of 2 measurements had a higher correlation with carcass fat measurement C and were better predictors of percentage carcass fat than measurements taken on either the same side of the sheep as the operator or the first 2 measurements. We conclude that different ultrasound backfat measurements vary in their value in predicting carcass fatness and individual operators should establish the most appropriate measurement.

Follicle and fleece characteristics of Merinos, Romneys and Merino-Romney crossbreds - Meikle HE; Wickham GA; Rae AL; Dobbie JL; Hickey SM (Proceedings of the New Zealand Society of Animal Production, 1988)
In the first of 2 experiments, the milk production, food conversion efficiency, and grazing uniformity of Friesians and Jerseys were compared during a grazing trial of 21 d duration in mid lactation. Four groups of each breed, consisting of 12 cows per group, were offered pasture allowances of 10, 20, 30 or 40 kg dry matter (DM)/cow/d. In experiment 2, the energy metabolism of 6 Jerseys and 6 Friesians was compared by means of open circuit calorimetry. Energy balances were established for each cow when offered pasture at ad libitum, and at 75% National Research Council (NRC) requirements. In Experiment 1, on average Friesians produced 26% more milk, 6% more milkfat, 13% more protein and 24% more lactose. At the lowest level of feeding (10 kg DM allowance/cow/d) Friesians produced more milk but less milkfat and protein than the Jerseys. Friesians consumed more pasture dry matter (av 13%), lost more live weight and had a lower food conversion efficiency (61 v 67 g milkfat/kg DM consumed) than the Jerseys. It was calculated that milkfat per ha, at a common live weight was lower for the Friesians than Jerseys particularly at high rates of stocking. Partitioning of gross energy into digestible energy or metabolisable energy was not significantly affected by breed in Experiment 2, but the efficiency of utilisation of metabolisable energy for milk and tissue (balance energy) was higher for Jerseys than Friesians (0.58 v 0.48 respectively). The results suggest that in mid lactation Friesians produce more milk and milk solids per cow than do Jerseys because of the greater feed intake of Friesians. In contrast, the higher food conversion efficiency, utilisation of metabolisable energy and dry matter consumption per unit live weight of Jerseys allows them to achieve a higher production per hectare than the Friesians. Comparisons between breeds at other stages of lactation is warranted, particularly in light of current discussions about the system of payment for milk.

A genetic approach to footrot control - Moorhouse SR; Skerman TM (Proceedings of the New Zealand Society of Animal Production, 1988)
Modern methods in molecular biology have immense practical application in many areas of agriculture and veterinary medicine. These methods include the use of enzymes (restriction endonucleases) that recognise and cleave DNA at specific sites, the cloning of specific fragments of DNA into suitable plasmid or bacteriophage vectors, separation of DNA or RNA fragments followed by fixation to a suitable membrane support, and the use of clones radioactive DNA or RNA probes to detect matching sequences by hybridisation. These methods have been combined to provide powerful new techniques to detect DNA polymorphisms that show Mendelian inheritance. Differences in DNA among individuals can be detected as restriction fragment length polymorphisms (RFLP) or by DNA fingerprinting. Both techniques are used extensively in medicine for the analyses of heritable genetic diseases and genetic mapping. They can also be applied to livestock to find DNA markers linked to important economic traits. We have recently begun screening human DNA probes in a search for RFLPs in New Zealand sheep breeds. The objective of the experiments is to find markers linked with Booroola fecundity (F) gene. Several human DNA probes show specific binding to sheep genomic DNA, demonstrating homology between sheep and humans for some DNA sequences. Techniques which identify linked markers will have immediate application in selection for important major gene traits such as genes affecting fecundity, fleece weight, and disease and parasite resistance. New Zealand is in a strong position to apply linkage studies to important production traits in existing breeding programmes.

Growth and carcass traits of purebred Texel and Suffolk sheep - McEwan JC; Hanrahan JP; Fitzsimons JM; Allen P (Proceedings of the New Zealand Society of Animal Production, 1988)
Feral does were used for a 2 x3 x 2 factorial, with 2 types of insemination (cervical v laparoscopic), 3 pregnant mare serum gonadotrophin (PMSG) levels (no PMSG, 150 i.u. 2 d before controlled internal drug releaser (CIDR) removal and 150 i.u. at CIDR removal) and 2 sperm dose rates (50 v 100 million sperm). The semen, obtained from 9 Cashmere bucks, was frozen in straws containing 100 million sperm. Three operators inseminated 171 does 2 d after CIDR removal. The overall kidding rate from cervical insemination was 24% and from laparoscopic was 50%. There was no effect of PMSG, sperm dose rate, buck or inseminator on the percentage of does kidding.

Improving the efficiency of utilisation of pasture protein by sheep - Dellow DW; Obara Y; Kelly KE; Sinclair BR (Proceedings of the New Zealand Society of Animal Production, 1988)
Two trials were conducted on water intake of red deer stages to provide a basis on which to determine water requirements for deer farms. In the first trial, water intake from a trough by 13 15-month-old deer stags was monitored for 16 days while they grazed dryland pasture during a spell of dry weather (March - April 1988) in Canterbury. Voluntary water intake (VWI) from the trough was 2.6 litre/hd/d and intake of water ingested in feed (40% DM) was estimated to be 4.2 litre/hd/d, giving a total water intake (TWI) of 6.8 litre/hd/d (or 0.19 litre/kg W0.75/d). In the second trial, 12 3- to 5-year-old stags were held indoors in pens and fed (n=6) either pasture silage (27% DM) or pellets (88% DM) in a crossover design with Period 1 of 33 days duration and Period 2 of 25 days. VWI and DMI were monitored daily for 15 days in Period 1 and 14 days in Period 2. TWI for silage was greater than for the pellets (10.6 v 4.6 litre/hd/d, respectively) but the stags drank more water when consuming pellets. There was evidence of a linear relationship between TWI and DMI.

Indirect selection for adult fleece weight using canonical discriminant functions of blood metabolites - Cottle DJ (Proceedings of the New Zealand Society of Animal Production, 1988)
The impact on beef herd performance of weaning calves before or after cows clean-up low quality summer pasture was assessed. Surplus pasture was cleaned-up by weaned cows, and unweaned cows and calves, using either a single hard grazing (1 x 56 d rotation) or 2 x 28 d rotations commencing 20 January in 1986 and 22 January in 1987. Pastures had accumulated about 4.5 t dry matter (DM) /ha after being retired from grazing in late November as a pasture control measure. Weaned calves were fed quality (70+% green) pasture at pre-graze masses of 1.5, 2.0 or 2.3 t DM/ha under set-stocking 1986, or a fast rotation, 1987. Unweaned calves gained 38 and 39 kg over the 8 weeks in 1986 and 1987, respectively. There was no effect of pasture clean-up method on calf growth. Calves in the best weaned treatment gained just 23 and 30 kg in 1986 and 1987, respectively. Weaned calves suffered from facial eczema (mean gamma glutamyl transferase )GGT) 290 iu) in 1986 which reduced their growth. The rank pasture reduced exposure to facial eczema (mean GGT cows and calves 15 iu) Calf age had no effect on calf growth rates. Weaned cows lost 3 and 15 kg in each year. Unweaned cows lost 20 kg more than weaned cows. Benefits of late weaning were increased calf growth and reduced demand for quality autumn pasture. They were considered to outweigh costs of cow liveweight loss.

Induction of ovulation in anoestrous red deer hinds with a GnRH analogue - Duckworth JA; Barrell GK (Proceedings of the New Zealand Society of Animal Production, 1988)
Mixed-age Coopworth ewes (594) were allocated to 18 groups on the basis of age and live weight. Three groups (n=33) were treated and joined every second month from June 1986 until April 1987. Ewes were treated with controlled internal drug releasers (CIDR) for 14 d and either 0, 400 or 800 iu pregnant mare serum gonadotrophin (PMSG) at CIDR removal. Entire Poll Dorset rams (10%) were joined at CIDR removal and changed every 6 h during oestrus. Data on interval from CIDR removal to onset of oestrus, duration of oestrus, ovulation rate, pregnancy rate and lambing performance were recorded for all groups. The interval from CIDR removal to the onset of oestrus increased in the non-breeding season and this was modified by PMSG treatment which shorted the interval. The duration of oestrus was shorter in the non- breeding season in ewes with no PMSG and longer in ewes with the higher dose of PMSG. Both dose levels of PMSG prevented the out-of-season reductions in the incidence of oestrus and ovulation. Ovulation rate increased with dose of PMSG and all treatments showed a seasonal change. A decline in conception rate was a major problem even in PMSG treated ewes during the non-breeding season.

The influence of abomasal infusion of protein or energy on ovulation rate in ewes - Cruickshank GJ; Smith JF; Fraser DG (Proceedings of the New Zealand Society of Animal Production, 1988)
Mixed-age Coopworth ewes (280) were allocated to an experiment in which the effects of immunisation against androstenedione, synchronisation with progestagen sponges, and exposure to the ram effect, on oestrus and ovulation were examined. The observations were commenced at 2 different times (mid-January and early February) prior to the commencement of the normal breeding season and continued until all ewes had exhibited oestrus and ovulated. Immunisation against androstenedione increased the ovulation rate (+0.60) at the ram-induced ovulation. However it suppressed the proportion of ewes exhibiting oestrus after sponge withdrawal at both times of ram introduction. Ewes isolated from the ram failed to ovulate and the first spontaneous ovulation was not recorded until 6 weeks after that recorded for ewes exposed to the ram effect. Pre-treatment with sponges was necessary for the ram-induced ovulation to be accompanied by oestrus. The extent of the ram effect was most noticeable with 95% of ewes exposed to the ram ovulating in January.

The influence of breed on the meat content of beef carcasses for export - Butler-Hogg BW; Morris CA; Baker RL; Bass JJ; Mercer G; Duganzich DM (Proceedings of the New Zealand Society of Animal Production, 1988)
A 2 x 2 x 4 factorial trial was performed (n=20), N=320) to investigate the effect of 2 levels of nutrition (high protein diet -23% crude protein v low protein diet - 10% crude protein) on the ovarian response to exogenous follicle stimulating hormone (FSH) administration in mixed-age Coopworth ewes. Two preparations of FSH were examined (FSH-P, Burns-Biotec and Folltropin(r), Vetripharm) at 4 different levels (0, 8, 16 and 24 mg equivalents FSH-P). The ovulation rate of both high and low protein intake ewes increased linearly in response to increasing FSH levels (0 mg = 1.2; 8 mg = 3.2; 16 mg = 7.9; 24 mg = 9.6). There was no difference in response between the 2 sources of FSH. Ewes on a high protein intake had a higher ovulation rate when FSH was not administered (mean ovulation rate

Inherited protein variation and parentage testing in farmed red deer - Tate ML; Dratch PA (Proceedings of the New Zealand Society of Animal Production, 1988)
Production data were collected over 3 years from a flock of 600 mixed-age ewes (approximately equal numbers of Romney, Coopworth and Perendale) shorn either once-yearly in October or twice-yearly in February and October. They were grazed as a single mob throughout the year, except over mating when they were divided into breed groups and joined with rams of their own breed. Twice-yearly shearing depressed total annual greasy wool production but did not affect total annual clean wool production. Twice-shorn ewes weaned 7% more lambs because of a reduction in barrenness. Shearing treatment did not affect live weight either pre-shearing in February or post-shearing in October, nor did it affect ewe and lamb survival. Incidence of casting was less than 1%. Overall economic returns for the 2 groups of ewes were similar with the greater net wool returns of the once-shorn ewes offsetting the greater net returns from the extra lambs weaned by the twice-shorn ewes. Extrapolation of the observed production trends suggested the net returns from once-yearly shearing pre-joining would be greater than the returns from either once-yearly shearing in spring or twice-yearly shearing pre-joining and again in spring.

Leanness of young sheep that lost weight after shearing - Bray AR; Taylor AG; Burton RN; Moss RA (Proceedings of the New Zealand Society of Animal Production, 1988)
The necessity to identify and utilize superior fibre producing goats has led to the demand for artificial breeding techniques to be developed within New Zealand. Particular emphasis has been placed on cervical insemination by Ambreed as it is seen as the most cost efficient methods, especially at a commercial level. Bucks have been selected on individual fleece data and stood on licensed artificial insemination centres at Cambridge and Kaiapoi. A total of 50 bucks have been trained for semen collection, with the training period varying from 5 minutes to 2 weeks. Collection from some individuals began as early as December, and continued until August. All semen used was frozen in a Tris-based egg yolk/glycerol diluent. Semen quality has been determined by post-freeze motility using a 2 sec photomicroscopic technique. Training courses lasting for 3 d have been held to instruct both visiting technicians and owner/operator type inseminators. In combination with Ambreed technicians operating directly from Cambridge Centre, approximately 15,000 goats were inseminated during the 1987 autumn period. Kidding data are currently being analysed and indications of pregnancy rate from non-return rates are currently in the 50-55% range.

Management for milkfat or protein, does it differ? - Thomson NA (Proceedings of the New Zealand Society of Animal Production, 1988)
The utilisation of a supplementary energy supply and its effects on urea metabolism and rumen function were examined in sheep fed indoors on fresh lucerne (Medicago sativa cv. Rere) (N content, 34 g/kg DM). Sheep were fed hourly and infused intraruminally with either water (1200 ml/d; n=5; N intake, 33.0 g/d) or similar volume containing sucrose (160 g/d; n=4; N intake, 32.1 g/d). The additional energy resulted in a lower rumen fluid ammonia concentration (264 v 142 mg N/l). In a comparable experiment with sheep fed chopped lucerne hay, continuous infusion of sucrose also resulted in increased propionic acid levels in the rumen which was reflected in an increase in plasma glucose production (113 v 188 g/d) in the infused group. The results suggest that supplementary fermentable carbohydrate is effective in improving the efficiency of utilisation of pasture protein. The effect appears to be 2-fold: excess ammonia-N i9s captured as microbial protein which is then available for enzymic digestion in the lower gut; the additional fermentative activity increases propionate production which in turn is available for glucose production, thus sparing amino acids for tissue protein utilisation.

Measurement of blood flow and amino acid metabolism in the skin of sheep - Harris PM; Dellow DW; Sinclair BR (Proceedings of the New Zealand Society of Animal Production, 1988)
Measuring pasture yields to achieve management goals on farms, or in regions, distant from research stations requires techniques both practical and sensitive to localised factors such as soil type, pasture species, and adapted management technology. In addition, such techniques must be compatible with any quantitative comparisons which need to be made between the farm and the distant research station. Pasture dry matter (DM) yield on a paddock scale is measured by a 2-stage process of yield estimation, and calibration to DM. Using data collected in Northland, this paper shows how the methods of DM yield assessment vary according to the end-use. For example, a cursory eye estimate without calibration is suitable for assessing DM for wintering livestock at high grazing pressure, while, for farm cover assessment, detailed yield estimation allied with detailed quadrat cutting could be necessary. The index of total DM used on research stations can be provided on farms by cutting techniques which measure only to a trimmed level and do not include the stubble component to ground level. The stubble component can be an extract value provided by an expert skilled in comparing different pastures.

Measuring pasture yield for livestock management on farms - Piggot GJ (Proceedings of the New Zealand Society of Animal Production, 1988)
Regurgitated and reswallowed rumination boli from 6 diets were collected from oesophageal fistulated sheep. After wet sieving, large particles retained on the 4mm sieve were treated with propan-2-ol and examined under a binocular microscope for types of structural damage. Particle types were identified as leaf, stalf, endodermis and cuticle. Bolus particle composition was different for each diet and for regurgitated and reswallowed material. The overall effect of rumination chewing on bolus composition was to increase the number of stalk particles retained on the 4mm sieve. Surface area (length x width) of particles was determined. Individual red clover leaf particles were markedly larger than all other particle types. Significant differences in individual particle surface area occurred in 2 ways after rumination chewing. For immature and mature ryegrass diets, surface area in stalk and leaf particles increased respectively but red clover, meadow hay and lucerne chaff showed decreased surface area of stalk particles.

Meat flavour of Romney lambs grazed under Pinus radiata - Percival NS; Hawke MF; Kirton AH; Hagyard C (Proceedings of the New Zealand Society of Animal Production, 1988)
Shearing immediately followed by underfeeding reduced carcass fatness in sheep aged 10 to 14 months. When compared with woolly, growing sheep at the same weight a combination of shearing and mild underfeeding lowered GR measurements by 1.5 to 6.3mm in 3 experiments. Although this practice is 1 of only a few management procedures that have been shown to consistently lower GR measurements at a given carcass weight it is not recommended as a routine production practice because of potential effects on animal health and welfare and meat quality.

The mechanism of action of growth hormone on milk production of ruminants - Davis SR; Hodgkinson SC; Gluckman PD; Moore LG; Breier BH (Proceedings of the New Zealand Society of Animal Production, 1988)
The effect of management on milk, milkfat and protein production was assessed by analysing information collected from 16 different experimental farmlets run over a 9 year period on the Waimate West Demonstration Farm and the Taranaki Agricultural Research Station. In these trials a wide range of stocking rates (2.7 to 4.5 cows/ha), pasture types (ryegrass, lucerne, tall fescue and phalaris) and management systems were used. Comparisons of production and regression analysis between and within years and treatments failed to detect any significant effects of variations in grazing management, stock rate and cow condition at calving on milkfat or protein production. Information from a relatively wide data base, covering a range of seasons, management systems and pasture types suggests that herd management for maximum protein production needs to be no different than for systems already researched and adopted for milkfat production.

Optimal cow replacement on New Zealand seasonal supply dairy farms - Harris BL (Proceedings of the New Zealand Society of Animal Production, 1988)
The use of computer models to predict the ratio of outputs to inputs can be considerable assistance in developing breeding objectives and assessing research priorities and evaluating the impact of changes in management on efficiency of production in the deer industry. Therefore we have developed a model (based on Parks (1982) which quantifies the inputs of feed and the output of carcass to calculate the biological efficiency of the hind/calf unit over the lifetime of the breeding hind. The model has been used to examine the effects of reproductive lifespan (age of culling), calving rate, twinning, changes in sex ratio and changes in calving date on efficiency. In all cases there was a peak in efficiency at 62-64 weeks of age. In terms of reproductive lifespan, the most efficient sustainable system involved slaughtering hinds after only 3 calvings, although the overall impact of this factor on efficiency was small. Changes in calving rate (proportion of hinds calving) had a marked effect with efficiency declining by 5 to 7% for a 10% decline in the calving rate. Twinning also had a major effect with about a 3% change for a 10% change in twinning rate although the higher pre-weaning mortality of twins compared with singles would markedly reduce real gains. Changes in the sex ratio also altered the efficiency of the system by 3 to 4% per 10% unit change in the proportion of males. In contrast, advancing the calving rate by 3 or 6 weeks did not change efficiency or live weight of progeny at the same age but did result in a 2.8% increase in live weight at the same date for every 3 weeks advancement in calving.

Ovulation rates in ewes selected for resistance to facial eczema and the effect of exposure to zearalenone - Smith JF; Campbell AG; Towers NR; Cow NR; McGowan LT; Wesselink C (Proceedings of the New Zealand Society of Animal Production, 1988)
Three mobs of mixed age Saanen milking does (n=15) were grazed separately on 3 suites of paddocks during the spring-summer lactation season between 1984 and 1985. Animals within mobs were drenched at 21 d intervals according to manufacturer's recommended dose rates with 1 of either ivermectin, oxfendazole or morantel. Ivermectin was given to all stock while not lactating. Seasonal patterns in faecal nematode egg count (FEC) were similar across all 3 groups. FEC regain measured 7 d after drenching suggested that effectiveness of the drench depended on the type used. Faecal cultures indicated that Ostertagia spp. and Trichostrongylus spp. were dominant during the summer months. Does with kids at foot were turned out for 76 d as tracers on the various suites at the end of the first trial. At slaughter, the dominant genus found was Ostertagia while appreciably fewer Trichostrongylus spp. were recovered. Significant differences in total worm burdens were detected between treatment groups. Drenching programmes appeared to have little effect on parasite control on pasture grazed solely by Saanen does. This is attributable to contamination established on pasture as well as the relative ineffectiveness of these types of drenches in this breed of goat when used at rates recommended for sheep.

Performance parameters in an autumn lambing ewe flock - Reid TC; Sumner RMW; Wilson LD (Proceedings of the New Zealand Society of Animal Production, 1988)
Among the factors influencing the productivity and profitability of livestock, animal diseases deserve special attention because they diminish the capacity of the animal to achieve its inherent potential level of production, for any given feeding and management regimen. Evidence concerning the nature of the various effects of disease is reviewed, and a hierarchy of effects is defined. The major effects are on protein metabolism and secondarily on energy metabolism. Effects on feed intake are also common, but even diseases which severely ravage the wall of the gastrointestinal tract do not appear as a general rule to significantly reduce feed digestibility. The primary effects of disease on nutrient metabolism flow through to various consequential effects on the productivity of the individual animal, and hence on herd replacement patterns and herd improvement. At least some diseases can continue to affect productivity even after the disease has been cured by treatment. Consequently, the adage that prevention is better than cure has a sound scientific basis. Analyses have shown exceptionally high economic returns from disease prevention, commonly 500 to 1500% return on invested funds. This is much higher than from curative methods in most cases. As veterinary science evolves from a curative approach towards an economically grounded health management approach, veterinarians will make use of evaluation aids through which the economic and practical implications of alternative actions are compared, so that the action most advantageous to the livestock enterprise can be taken.

Physical breakdown of forages during rumination - John A; Kelly KE; Sinclair BR; Reid CSW (Proceedings of the New Zealand Society of Animal Production, 1988)
This study was carried out to examine the efficacy and safety of an injectable copper (Cu) preparation (Coprin; Cu-EDTA, Pittman-Moore Animal Health, NZ) in deer and sheep. Treatments consisted of an injection of Coprin at three dose rates on two occasions five weeks apart. Liver biopsy samples were taken one week before and one and four weeks after each injection and 22 weeks after the second injection. Approximately 75% of the dose was present in the livers of sheep one week after each injection. However, while over 90% of the dose was present in the livers of deer one week after the first injection, less than 65% of the second injected dose was present after one week. Total plasma Cu was elevated for one week after the second injection only, the increase being proportional to dose rate. Plasma activities of aspartate transaminase, gamma-glutamyl transferase and sorbitol dehydrogenase were transiently elevated after the second injection, although not sufficiently so to indicate a state of toxicity. The product was found to be effective for rapidly increasing the Cu concentration of the liver in both sheep and deer. There appeared to be no significant ill-effects in either sheep or deer at twice the recommended dose for sheep.

Production and characteristics of wool from the hogget progeny of sheep intensively screened for fleece weight - Hawker H; Dodds KG; Andrews RN; McEwan JC (Proceedings of the New Zealand Society of Animal Production, 1988)
Dairy farmers made management decisions each season about which cow to replace. At present dairy farmers can use the production index. The production index is an historical measurement of a cow's milkfat production ranking, free from the influences of herd environment, age, stage of lactation and herd genetic level. A dynamic programming method is outlined which incorporates genetic, reproductive and economic information. This method ranks cows on their annualised present value. A sensitivity analysis was undertaken and the effects of the changes in the different economic parameters are discussed. The optimal cow rankings produced by the dynamic programming method were shown to be robust to changes in milkfat, manufacturing beef and heifer replacement prices and interest rate.

Se, Cu, Zn and Fe metabolism of the young lamb - Grace ND; Watkinson JH (Proceedings of the New Zealand Society of Animal Production, 1988)
No abstract supplied

Seasonal changes in oestrus, ovulation and conception of Coopworth ewes treated with CIDRs and PMSG - Smith JF; Cruickshank GF; McGowan LT; Parr J; Mortimer BJ (Proceedings of the New Zealand Society of Animal Production, 1988)
Recent interest in mating ewes at non-traditional times has increased the risk of sporidesmin poisoning (facial eczema) during mid to late pregnancy and lactation. In this pilot study, autumn mated ewes dosed with sporidesmin during pregnancy were used as a model to study the effects of sporidesmin poisoning on production. Ninety ewes were randomised into 3 equal sized groups and were dosed with either a low (0.125 mg/kg live weight) or moderate (0.250 mg/kg) dose of sporidesmin at 120

Short- and long-term effects of intestinal parasitism on growth in sheep - Young MJ; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1988)
Skin and fleece samples were taken from 637 ewes of Romney (R), Superfine Merino (SFM), Local Merino (LM), Superfine Merino x Romney (SFMxR), Local Merino x Romney (LMxR) and Backcross (BX) (3/4 SFM) genotypes. Secondary to primary follicle ratio (S/P), total follicle density (n(P+S), primary follicle density (nP), mean fibre diameter (MFD), quality number (QN), staple length (SL); total crimp number (TCN); live weight (LWT) and greasy fleece weight (GFW) were evaluated. Differences between the various genotypes, ages, years of sampling and birth/rearing ranks for these follicle and fleece characteristics were analysed. There were between genotype differences in significance of fixed effects. Genotypes having Merino ancestry with much large follicle populations had more significant fixed effects, but year of sampling and birth/rearing rank were seldom significant. Repeatability estimates for follicle and fleece characteristics ranged fr4om 0.44 to 0.89. Total follicle density and primary follicle density were positively correlated but the degree of association was higher between S/P and n(P=S). Both within and across genotypes, the correlations between S/P and MFD were negative. The low correlations between nP and GFW reflect the genotypes studied, nP having less effect on GFW and MFD in breeds with Merino ancestry. Heterosis was estimated in several ways, the means of groups representing the parent breeds being compared with the mean of each generation of the crossbred genotypes. The follicle traits, as well as MFD and QN showed negative heterosis. Live weight and GFW showed positive heterosis in the F1 SFMxR and LMxR groups of 6.84 kg, 5.99 kg and 0.18 kg and 0.47 kg respectively. The crossbreds weighed more and produced heavier fleeces than the purebreds but with no concomitant increase in MFD over the parental breed mean.

Some measurements of ruminated forage particles - Kelly KE (Proceedings of the New Zealand Society of Animal Production, 1988)
Differences between sheep and deer in the effects of molybdenum (Mo) and sulphur (S) on copper (Cu) metabolism were investigated in two dietary experiments each using 8 animals of each species. The animals were offered a hay diet supplemented (Expt 1) to contain 3, 6, 12 or 24 mg MO/kg DM and 2.3 g S/kg DM or (Expt 2) to contain 6, 12, 24 or 48 mg Mo/kg DM and 5.3 g S/kg DM. The duration of the feeding periods was 35 and 16 days, respectively. With the low S diet (Expt 1) total plasma Cu was changed from the pre- experimental level of 0.75 to 0.63, 0.77, 0.81 and 1.03 mg/litre, respectively, in sheep and from 0.95 to 0.77, 0.79, 0.67 and 1.01 mg/litre in deer. The proportion of trichloroacetic acid (TCA) soluble/total Cu was reduced by 0.05, 0.09, 0.07 and 0.21 in sheep and by 0.01, 0.05, 0.08 and 0.11 in deer. With the high S diet (Expt 2) total plasma Cu concentration changed from 0.81 to 0.82, 0.97, 1.43 and 1.41 mg/litre in sheep and from 1.08 to 0.72, 0.96, 0.88 and 1.21 mg/litre in deer. The proportion of TCA- soluble/total Cu was reduced by 0.20, 0.50, 0.60 and 0.63 in sheep and by 0.05, 0.10, 0.23 and 0.48 in deer. This study has shown that Cu metabolism in sheep is more sensitive than in deer to increasing dietary Mo concentration. While plasma total Cu increased with increasing Mo in the diet in sheep, concentrations declined in deer. This was associated with a greater induction of insoluble Cu in plasma in sheep. In both species increased dietary S enhanced the effect of dietary Mo on Cu metabolism, but deer appeared to be more sensitive than sheep to increasing dietary S concentration.

Sporidesmin poisoning in ewes during late pregnancy - McMillan WH; Dockrill G; Towers NR (Proceedings of the New Zealand Society of Animal Production, 1988)
Forty-eight animals were allocated to 1 of 3 treatments (C = continuous growth; I = infected with 4000 larvae/d of Trichostrongylus colubriformis; P= individually paired with I animals for change in live weight) in a serial slaughter experiment examining the effects of intestinal parasitism on bone and muscle in young growing sheep (25 to 45 kg). Both I and P groups were nutritionally rehabilitated after the I group had undergone an 83 d period of infection. While I and P groups underwent similar changes in live weight during the period of infection, feed intake of the P group became progressively less than that of the I group. By the end of infection I animals were consuming approximately 30% more feed than P animals. During the period of infection both I and P groups lost live weight. Of the body chemical components, fat was depleted to the greatest degree (48% loss) followed by protein (23% loss). While bone displayed growth in external linear dimensions (length = +4%; diameter = +6%) there were significant reductions in protein (22%) and cortex width (33%). In contrast muscle showed decreases in all chemical components and in diameter. This greater effect on muscle was exaggerated in the I group. Infection led to greater reductions in muscle protein (45% v 34% (I v P)) and muscle diameter (19% v 8%). There were no appreciable differences between the I and P groups for changes in bone variables. While specific effects of infection on growth of muscle were found, change in most variables was largely attributable to the general restriction in growth consequent upon undernutrition. Subsequent to the period of parasitic infection, compensatory growth occurred such that muscle recovered relative to bone. There was some evidence that full recovery of muscle relative to bone was delayed in animals recovering from a parasitic infection.

The stability of the relationship between subcutaneous fat percent in the rack and the side for Southdown ram carcasses - Kadim IT; Purchas RW; Rae AL; Barton RA (Proceedings of the New Zealand Society of Animal Production, 1988)
The carcass composition of pasture-fed crossbred ram lambs of the Finn, Texel, Oxford Down, Border Leicester and Suffolk breeds was compared at the Hopuhopu Animal Quarantine and Research Station in 1987. Early results were in close agreement with overseas studies which have highlighted the low subcutaneous fat depth of Texel crossbreds in comparison with lambs from Suffolk sires at the same carcass weight. Finn crossbreds were relatively lean subcutaneously but had relatively more kidney fat. Texel crosses showed superior eye muscle development at constant carcass weight.

Weights of some body organs from cattle selected for high and low susceptibility to bloat - Carruthers VR; Morris CA (Proceedings of the New Zealand Society of Animal Production, 1988)
This paper reports preliminary studies to determine the normal variation in blood flow, amino acid uptake and protein metabolism in a defined area of skin on 45 kg Romney wethers. Four sheep were catheterised in branches of the deep circumflex iliac artery and vein to allow measurement of arterio-venous concentration differences and blood flow (using dye dilution techniques) in a 560 cm

Accessing of slaughterhouse information to livestock production systems - Hathaway SC; McKenzie AI (Proceedings of the New Zealand Society of Animal Production, 1987)
The trial reported in this paper was undertaken at the Rotomahana Research Station to compare the performance of sheep of different genetic background and breeding history. Border Leicester, Coopworth and Romney rams from different sources were mated to Romney ewes representing a wide range of genetic sources between 1979 and 1983. Rams from 6 Romney strains were sampled including a commercial industry sample, the Ruakura High Fertility (RHF) flock, a Romney stud and 3 group breeding schemes. The Coopworth ram source was also a large group breeding scheme. Data collected on the first cross females born between 1979 and 1983 and lambing between 1981 and 1985 are summarised in this paper. Analyses of ewe hogget performance (growth, wool production and oestrous activity) revealed relatively minor variation among the 6 Romney strains, with the exception of greater oestrous activity in RHF-sired hoggets. Coopworth and Border Leicester crosses were heavier, had higher fleece weights and showed more oestrous activity than straightbred Romneys. Highest reproductive performance was obtained from Coopworth and Border Leicester crosses reflecting breed differences, positive heterosis and heavier ewe body weights. Among the 6 Romney strains greatest variation in reproductive performance was seen for litter size with the RHF-sired ewes excelling and also having the best performance for lambs weaned per ewe joined and lambs weaned per ewe joined as a ratio of ewe body weight. Similarly, the litter size advantage for ewes sired by rams from the 3 Romney group breeding schemes demonstrated that selection for reproductive performance over a period of 10 to 15 years has been successful.

Agricultural education in New Zealand - Anderson RD (Proceedings of the New Zealand Society of Animal Production, 1987)
Waste by-products and crop residues are a valuable source of feed for ruminants. In many instances low feed quality and acceptance limit the utilisation of these resources. The main factors influencing acceptance are the chemical and physical characteristics (palatability factors) of feedstuffs and the dietary experience and social environment of the animals. The likely acceptance of a new product, relative to that of many other rations, can be predicted from its position on a preference scale. Exposure of sheep or cattle to feedstuffs early in life can produce large increases in the rate of acceptance of, and proportions of animals consuming, typically unpalatable items. It is clear that by manipulating early feeding experiences and other factors determining ration acceptance the utilisation of by-products and residues by livestock can be increased substantially.

An assessment of the rate of fat accumulation in ruminant adipose tissue in vitro - Lewis KJ; Molan PC; Bass JJ (Proceedings of the New Zealand Society of Animal Production, 1987)
The cold resistance (CR) of 468 new-born lambs was measured by immersion of lambs in a progressively cooling water bath. The ability to withstand cold (CR time) was defined as the time taken from the start of water cooling until the lamb's rectal temperature reached 35

Barley consumption by lambs during transfer from pasture to barley-based diets - Bray AR; Moss RA; Burton RN (Proceedings of the New Zealand Society of Animal Production, 1987)
Stocking rates and target live weights to optimise profit on a small bull beef unit were determined from the New Zealand Exporters Schedule for bull beef and liveweight gain information. The targets were to purchase bulls during October or November at 85 to 100 kg live weight and to grow them to between 420 and 440 kg live weight by 1 December the following year. Using average pasture growth rate data, a simple feed budget model predicted mean pasture cover targets from April to December required to achieve the live weight targets. Grazing plans were designed and regularly reviewed to test the validity of using mean pasture cover as an indicator of successful management.

Behavioural factors influencing by-product and residue acceptance by livestock - Matthews LR (Proceedings of the New Zealand Society of Animal Production, 1987)
This paper reports on an interactive, user-friendly microcomputer based pasture production model which provides pasture growth rate information for farmers and advisers. The model (GRASS) describes the production of perennial ryegrass and white clover pastures in terms of simplified major processes. The model not only allows for assessments of historic and current (daily) growth rates, but can also make rapid analyses of future pasture growth rates. This predictive ability is of major importance in many management decisions. The model also allows for on-site calibration. It is intended to be used on individual farms and any management can be simulated. This model overcomes the limitations of pasture growth data collected at research stations over a limited number of years using standard cutting techniques at sites which are often not representative of the climate and soil types on a particular farm. Examples of potential uses for the model are given. It is concluded that an explanatory low resolution model appears to be a promising approach for more sophisticated feed planning and management decisions.

Bone growth and muscularity - Young MJ; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1987)
Highly prolific flocks of Romney, Coopworth and Perendale sheep have been established from the progeny of ewes screened from industry. Ovulation rates of 1.5-year-old Romney, Coopworth and Perendale ewes were 1.82, 2.08 and 1.87 respectively. Corresponding ovulation rates for older ewes were 2.13, 2.27 and 2.07. Mean litter size of 1.5-year-old Romney, Coopworth and Perendale ewes was 1.63, 1.87 and 1.61 respectively and for older ewes the respective litter size was 1.88, 1.94 and 1.78. The proportion of ewes twinning ranged from 0.57 to 0.69. Within the flocks there are some family lines which are showing outstanding prolificacy and are the subject of a progeny testing programme.

Bull beef production on hill country - Journeaux PR; McRae AF; Parker WJ (Proceedings of the New Zealand Society of Animal Production, 1987)
The aims of this study were to compare ovarian and oestrous activity in ewes teased over a range of dates in late anoestrus by either rams or bucks. Entire Dorset rams or feral bucks (male goats) were joined with anovular Romney ewes on either January 20, 27; February 3, 10 or 17 in a 2 x 5 factorial design (N=350). Ovulations were determined 4 d later and first oestrus up to 6 weeks later. On day 8, ovulations were determined in ewes anovular on day 4 to buck teasings. Spontaneous ovulations first occurred in mid February. Rams were more effective than bucks at inducing ovulations. Furthermore, rams induced ovulations in ewes that failed to respond to bucks. Date of teasing had no effect on the pattern of first matings in ovulating ewes. Ewes stimulated to ovulate by rams tended to display oestrus earlier than ewes stimulated by bucks. These results demonstrate that rams and bucks will initiate early ovulation and oestrus in ewes, but rams are superior teasers to bucks.

A comparison of lamb growth rate and lean carcass gain within and among farm flocks - Geenty KG; Dyson CB; Scales GH; Ward C (Proceedings of the New Zealand Society of Animal Production, 1987)
The viability of a number of bull beef production systems integrated with sheep, within summer dry and summer wet hill country environments were examined using a spreadsheet feed budget simulation model. A survey of commercial hill country farmers was also undertaken to identify on-farm problems and opportunities. The study demonstrated that bull beef systems can be profitably integrated with sheep on hill country, and that farming bulls for beef on hill country is likely to increase. Survey farmers had few problems with bull misbehaviour and had achieved liveweight gains similar to or higher than those used for modelling purposes throughout the year, although not consistently during the autumn and winter. These farmers could improve profitability by setting up a separate wintering area for bulls or integrating their grazing with ewe hoggets rather than older sheep.

A comparison of spring and autumn calving for beef cattle production - Montgomery GW; Davis GH (Proceedings of the New Zealand Society of Animal Production, 1987)
Rapid expansion of the mussel farming industry in New Zealand, from an annual production of 300 t in 1977 to about 12,000 to at present resulted from the introduction of the longline system. This simple, efficient, low cost and aesthetically acceptable system allowed the new industry to exploit the rapid growth rate and available supplies of spat of the green-lipped mussel (Perna canaliculus). Spat supplies, food availability and market expansion are possible constraints on the continued growth of the mussel industry. The economics of growing, harvesting, processing and marketing hold the key to the industry's future potential.

Computer aided tomography - comprehensive body compositional data from live animals - Young MJ; Garden KL; Knopp TC (Proceedings of the New Zealand Society of Animal Production, 1987)
A proposal for the development of a three-stage computer-based system for the acquisition and retrieval of disease and defect data for lambs slaughtered in export premises is described. Stage 1 is an extension of the existing manual ticketing and administrative routine. A slaughter-line computer keyboard would allow continuous collection of data on an individual flock basis, as well as significantly decreasing meat inspector, processor and information servicing workloads. The data base would also provide a statistical base for regulatory decisions and assist the processor's quality control programme. Stage 2 is a vertical integration of the inspection service with other agencies involved in the livestock production system. Long-term aims are promotion of producer efficiency and payment by quality. By accumulating both individual and regional flock health profiles, differential cost-effective processing and inspection programmes can be applied. Production and market-related disease and defect data has wide application as a commercial resource. Stage 3 is an integrated meat inspection system with a national disease and residue surveillance centre.

An effect of copper supplementation on growth of beef cattle in Northland - Reid TC; Shannon PW (Proceedings of the New Zealand Society of Animal Production, 1987)
Oestrous synchronisation in ewes is normally achieved using polyurethane sponges containing progestagen. The recent development of silicone elastomer controlled internal drug releasers (CIDR) offers an alternative synchronising technique. The appropriate duration of CIDR treatment and timing of ram introduction has yet to be determined. Romney ewes had a CIDR type G inserted on the same date and withdrawn either 11, 12, 13, 14 or 15 d later (Trial 1). The ewes were joined in single sire groups with 9 rams at CIDR withdrawal. This confounding exists between duration and days since ram matings commenced. Matings were recorded over days 1 to 7 and 15 to 21. Cheviot ewes were jointed in single sire groups with 5 rams at either 30 or 48 h after CIDR withdrawal (Trial 2). Matings were recorded on days, 2 3 and 15 to 21. Pregnancy status was assessed by ultrasonic scanning. In Trial 1 more ewes mated by day 1 following 11 and 15 d CIDR durations than 11 to 13 d durations (10% and 7% v 4%). Apart from this, longer durations were associated with fewer ewes subsequently mating. There was no association between duration of CIDR treatment and return matings, pregnancies to first service or multiple pregnancies. However, overall more ewes were pregnant following intermediate durations. In Trial 2 most of the ewes jointed at 30 h had mated by 48 h. By day 3, nearly all ewes had mated in both groups. Non-return rates (80% v 63%) and first service pregnancy rates (70% v 58%) were higher in ewes joined at 30 h than at 48 h. The final pregnancy rate was similar in both groups (88% v 90%). CIDRs should be timed to be withdrawn at 12 to 14 d to maximise pregnancy rates to 2 rounds of mating when ewes are progressively joined with rams. Joining rams at 30 rather than 48 h after withdrawal results in earlier lambing since more ewes are pregnant to matings at the synchronised oestrus.

Effect of different shearing policies on sheep production in Northland - Sumner RMW; Armstrong D (Proceedings of the New Zealand Society of Animal Production, 1987)
Goat farming as a form of livestock farming has developed in New Zealand since the mid 1970's. The main cause for this has been the change in the relative economics of the traditional pastoral farming industries of sheep, beef and dairy cows. Farmers have begun to recognise the husbandry and economic aspects of farming goats and have been developing techniques for profitable ventures. Export earnings from goats approached $4 million FOB in 1983-84 but have varied considerably since with the availability of stock for slaughter, dairy goat product market fluctuations, and stock value changes.

The effect of selenium supplementation on milk production in dairy cattle - Fraser AJ; Ryan TJ; Sproule R; Clark RG; Anderson D; Pederson EO (Proceedings of the New Zealand Society of Animal Production, 1987)
A method for the evaluation of the rate of fatty acid accumulation and recycling in adipose tissue in vitro is described. The influence of insulin on fatty acid accumulation in adipose tissue is shown to be greater than its influence on fatty acid manufacture. This was achieved by the ability of the hormone to reduce the rate at which fatty acid was mobilised from the adipose tissue. It is proposed that studies of the total fatty acid balance in this tissue will provide a better understanding of the effects of hormones on overfatness in meat animals than a study which simply addresses the rate of fatty acid manufacture.

Effect of steroid immunisation and vaginal artificial insemination on the fertility of synchronised ewes - Moore RW; Lynch PR; Miller CM; Welch RA (Proceedings of the New Zealand Society of Animal Production, 1987)
No abstract supplied

The effect of steroid immunisation on the seasonal pattern of oestrus, ovulation and ovulation rate in Coopworth ewes - Smith JF; McGowan LT; MacLean KS; Farquhar PA (Proceedings of the New Zealand Society of Animal Production, 1987)
Significant numbers of livestock in New Zealand are now grazed on the understorey of Pinus radiata. Fresh foliage of radiata pine contains aromatic monoterpenes and decaying needles resin acids. As livestock grazed under trees are know to eat both fresh and decaying pine needles, a study was made to find out if the meat quality characteristics of lambs grazed under P. radiata were affected. Groups of Romney wether lambs were grazed for 49 d under P. radiata at 100 and 200 stems/ha and on open pasture (no trees). In addition, 2 groups were stall fed for 21 d with 23 and 21% of their intake as fresh or decaying pine needles respectively. All the lambs were slaughtered on the same day. Meat samples from each were subjected to a range of meat quality tests. Meat from the lambs grazed under the trees, or consuming fresh or decaying needles had slightly different colour and muscle pH levels, but there were no significant effects on its flavour, aroma, texture, juiciness or tenderness. It was concluded that there are no meat taints associated with lambs grazed under radiata pine.

Effectiveness of the New Zealand brucellosis control scheme for sheep - Bruere AN; West DM (Proceedings of the New Zealand Society of Animal Production, 1987)
Three trials were completed using 1813 cows in seasonal dairy herds to study the effects of an injection of a prostaglandin F2alpha, dinoprost tromethamine (Lutalyse

Energy nutrition of young red deer (Cervus elaphus) hinds and a comparison with young stags - Suttie JM; Fennessy PF; Veenvliet BA; Littlejohn RP; Fisher MW; Corson ID; Labes RE (Proceedings of the New Zealand Society of Animal Production, 1987)
Salmon farming began in New Zealand in 1976 with the introduction of ocean ranching. With this method of aquaculture, juvenile salmon are reared in freshwater and then released to the sea where they grow and subsequently return as adults at 2, 3 or 4 years of age to the freshwater release point. Two other methods of culture are also being practised, sea cage rearing and freshwater pond culture. With these 2 methods the salmon are reared to market size while fed an artificial diet. The increased rearing costs of these 2 methods of culture is offset by the higher survival of juvenile salmon to market size compared with ocean ranching. With ocean ranging 1-2% survival is considered the minimum necessary for a successful operation while returns of over 3% have been received at some hatcheries. Salmon production has increased from about 200 t in 1984-85 season (October to March) to 712 t in 1986-87. Exports in 1986-87 were approximately 353 t valued at $NZ4 million.

Facial eczema in hill country - potential toxicity and effects on ewe performance - Sheath GW; Webby RW; Boom RC (Proceedings of the New Zealand Society of Animal Production, 1987)
Milk responses to selenium supplementation were measured in 12 dairy herds of low selenium status as indicated by blood selenium concentrations of less than 150 nmol/l (<12 ug/l). In 4 of the herds milk responses were measured for 2 successive seasons. Milk volume responses to selenium varied from -2.6% to +10.4% (mean +4.6%) and milk fat responses from -4.0% to +10.2% (mean +3.7%). Significant (P<0.05) milk volume responses occurred on 2 farms in the first season and milk fat responses on 2 farms in the second season. A negative relationship (P<0.01) was found between milk fat response (%) to selenium (FatSe) and blood selenium concentration (nmol/l) (BSe) for herds in their first season of supplementation of:- FatSe) = 9.6 - 0.059 BSe. There was no relation between these parameters in the second season of supplementation.

Genetic aspects of cold resistance in new-born lambs - Wolff JE; Baker RL; Dobbie PM; Ford AJ; Jordan RB (Proceedings of the New Zealand Society of Animal Production, 1987)
Nine red deer hinds run as 2 groups were fed to appetite on a concentrate diet, indoors, from 5 to 17 months of age. Group food intake and individual liveweight gains were recorded. Food intake varied seasonally with greater amounts being consumed in summer than winter. Similarly liveweight gain was faster in summer than winter. From the relationship between intake and liveweight gain it was calculated that the hinds need 0.52 MJ metabolizable energy (ME)/kg 0.75/d for maintenance and require 55 MJ ME/kg for liveweight gain. These values result in slightly higher requirements for hinds than previously reported. In comparison with age matched stags, hinds have lower amplitude seasonal fluctuations in food intake and live weight and although maintenance requirements are similar between the sexes, stags require less energy for growth.

Genetic variation among six strains of Romneys and Border Leicester and Coopworth crosses - Baker RL; Clarke JN; Meyer HH; Harvey TG; Bigham ML (Proceedings of the New Zealand Society of Animal Production, 1987)
In an 11 month copper supplementation trial in Northland, weaner steer (initial live weight 210 kg) showed decreased liveweight gain when supplemented with copper, from November to March. Pasture copper concentrations were adequate throughout the trial. Serum copper concentrations tended to be low, especially in spring.

Growth potential and constraints in the New Zealand mussel farming industry - Hickman RW (Proceedings of the New Zealand Society of Animal Production, 1987)
Treatment with progesterone impregnated controlled internal drug releasers (CIDR) in early pregnancy can increase ewe reproductive performance. Return mating patterns, pregnancy rates and multiple pregnancies were evaluated in supplemented ewes and hoggets. Supplementation was over the 5 d from day 7 to 9 until day 12 to 14 post-mating. Supplementation had no effect on the pattern and incidence of return matings in ewes. In contrast, supplemented hoggets tended to return later with less returning (18% v 35%). Supplementation had no effect on ewe pregnancy rate although more supplemented hoggets lambed to first service (79% v 56%, P<0.05). Supplementation increased multiple pregnancies resulting in 23% more foetuses in ewes and 40% more in hoggets. The progesterone supplemented sheep may be a useful experimental model for studies in reproductive wastage.

Importance of dry matter content to voluntary intake of fresh grass forages - John A; Ulyatt MJ (Proceedings of the New Zealand Society of Animal Production, 1987)
The data from 2 series of trials were used to examine the effects of variation in leaf, green and total allowance on the herbage intake and milk production of dairy cows and the liveweight gain of weaned lambs over late spring and summer. Both the herbage intake and milk production of dairy cows and the liveweight gain of lambs were better related to leaf allowance than to green or total herbage allowance. With lambs, however, there were differences in liveweight gain at similar leaf allowances between experimental periods. These were largely accounted for by the percentage of dead herbage in the pasture. It is suggested that differences in animal performance over late spring and summer may be influenced by the level of leaf mass and dead matter in pasture but not the level of green grass stem.

Livestock diversification in New Zealand involving goats for meat and dairy production - Horton CT; Dawson JE (Proceedings of the New Zealand Society of Animal Production, 1987)
Two hundred 5-year-old Coopworth ewes were allocated to 4 groups in December 1983. Two groups (1 of which had been given a booster treatment of Fecundin(r) on 21 December) were treated with progesterone impregnated intravaginal sponges and joined with vasectomised Southdown rams on 19 January 1984. Oestrous data were recorded daily and ovulation rate determined by laparoscopy at each cycle thereafter. The other 2 groups (1 of which received a booster on 5 May 1984) were also treated with progesterone impregnated intravaginal sponges and introduced to rams on 1 June 1984. Oestrous and ovulation data were recorded until mid-September. Immunisation had no effect on the percentage of ewes exhibiting oestrus whereas season had a significant effect with an increase from 18% in January to a peak of 95% in April. This level of oestrous activity was maintained until the end of July after which there was a rapid decline. The proportion of ewes ovulating showed a similar pattern although peak values were attained early in February. Ovulation rate showed an increase up to March, plateauing until early July, and then declining. Values for immunised ewes were significantly higher than controls and persisted for at least 6 months in the early treatment group. These data show that although immunisation does not adversely influence the pattern of oestrus and ovulation activity in ewes subjected to the ram effect, early treatment appears to prolong the ovulation rate response.

The male effect - a comparison of rams and bucks for teasing ewes - McMillan WH (Proceedings of the New Zealand Society of Animal Production, 1987)
No abstract supplied

The New Zealand scheme to accredit goat flocks free from caprine arthritis-encephalitis - Merrall M; MacDiarmid SC (Proceedings of the New Zealand Society of Animal Production, 1987)
X-ray computer aided tomography (CAT) is shown to be a unique method of obtaining data pertaining to body composition in live animals. Comprehensive data were obtained from CAT images, dissection and chemical analysis of 5 sheep. Tissue (fat, lean and bone) volumes are accurately determined. Reference cross-sections are shown to be useful predictors of whole body composition.

Nutritive value of Lotus corniculatus L. containing low and medium concentrations of condensed tannins for sheep - Waghorn GC; John A; Jones WT; Shelton ID (Proceedings of the New Zealand Society of Animal Production, 1987)
A linear programming model has been developed which allows investigation of alternative dairy production systems. Simulation models used in conjunction with the linear programming model were then used to help set performance standards for on farm animal productivity. Information from these model sources is seen as an aid to decision making on farms and as an opportunity for managers to better understand the basic relationships that apply within their farming system.

Pasture quality and animal performance over late spring and summer - Butler BM; Hoogendoorn CJ; Richardson MA (Proceedings of the New Zealand Society of Animal Production, 1987)
The impact of a facial eczema outbreak on ewe performance, and its link to pasture conditions, was assessed within a farmlet experiment that investigated aspects of managing pasture surpluses in hill country. Late disposal of lambs and grazing steep land during periods of high spore numbers increased facial eczema in ewes. These effects can be associated with grazing lower pasture masses. In addition to clinical facial eczema deaths, there was a 2 - 3% increase in barren ewes and a 5-7% reduction in multiple births for every 100 i.u. increase in serum gamma glutamyl transferase levels. Pithomyces chartarum spore numbers were highest in easy contoured and north to north-west facing paddocks and in ryegrass dominant microsites. Numbers were least in south to south-west facing paddocks and in pastures dominated by low quality herbage and/or low fertility demanding grass species. The effects of facial eczema may well be reduced, but not necessarily eliminated, if the variability in potential toxicity is understood and wisely managed.

Post-mating progesterone supplementation in ewes and hoggets - McMillan WH (Proceedings of the New Zealand Society of Animal Production, 1987)
Castrate male and female lambs (n=8) received no treatment (O dose) or a silicone rubber implant containing 3 mg (L dose), 22 mg (M dose) or 52 mg (H dose) of oestradiol, respectively. Implants were placed subcutaneously at 8-10 weeks of age (mean weight 20.4 kg) and the animals slaughtered 180 d later. Oestradiol treatment decreased length of cannon bone but increased length of vertebral column and 12th rib. Cessation of growth in an early maturing bone (cannon bone) appeared to be accelerated by the treatment so that length was reduced. Later maturing bones (rib and vertebrae) showed a dose-dependent stimulation of linear growth. It is concluded that oestrogens accelerate the natural process of skeletal maturation.

The potential to increase production efficiency from animal-pasture systems - Leaver JD (Proceedings of the New Zealand Society of Animal Production, 1987)
A reduction in nitrogen degradation in the rumen of sheep fed fresh Lotus corniculatus containing 2.3-3.5% condensed tannin (CT) in dry matter has been demonstrated in two experiments. Protection from degradation appeared to favour amino acids essential (EAA) to sheep so that in the presence of 2.2% CT, 50% more EAA and 14% more non-essential amino acids essential (NEAA) reached the abomasum. Apparent absorption of EAA from the small intestine was 62% higher, and for NEAA 9% lower than in sheep fed the same diet where CT was made ineffective by ruminal infusion of polyethelene glycol. An increased absorption of EAA could explain the high nitrogen retention reported in this and previous experiments where sheep have been fed forages containing low to medium concentrations of CT. CT did not affect digestion of carbohydrate fractions in the rumen, or over the whole digestive tract. Aspects of microbial growth, rumen pool size, fractional outflow rates and particle size of rumen digesta were determined and are discussed.

Predicting animal production from pasture - Milligan KE (Proceedings of the New Zealand Society of Animal Production, 1987)
The basis and protocol of a national industry-based scheme aimed at controlling the spread of brucellosis in rams is described. It was designed by representatives of the Sheep and Beef Cattle Society of the New Zealand Veterinary Association, the Animal Health Division of the Ministry of Agriculture and Fisheries and sheep breed societies. As a national scheme it involves co-operation between veterinarians, sheep breed societies and farmers as well as the Ministry of Agriculture and Fisheries. Before official adoption of the scheme a considerable number of ram flocks had already been freed from brucellosis by field veterinarians using the highly sensitive and specific complement fixation test (CFT) for diagnosing carrier animals. With the establishment of the scheme results to date indicate that the majority of ram breeding flocks are now brucellosis free with a low overall prevalence of the disease.

Predictive use of a pasture production model on commercial farms: some examples - Baars JA; Rollo MD (Proceedings of the New Zealand Society of Animal Production, 1987)
A voluntary scheme directed towards limiting the spread of caprine arthritis-encephalitis (CAE) during a period of rapid growth of the goat industry is described. The scheme was instituted at the request of the goat industry and formulated after consultation with the New Zealand Goat Council, the animal Health Division of the Ministry of Agriculture and Fisheries and representatives of the New Zealand Veterinary Association. Prior to the development of the programme, surveys of the New Zealand goat population indicated that the disease was present in few flocks, largely those containing imported goats of superior genetic merit. The scheme was instituted in 1984 to limit the dissemination of the infected goats throughout the national flock. Testing was initially performed using the agar gel immunodiffusion test (AGID) but some doubts over its sensitivity lead to the development of an enzyme linked immunosorbent assay (ELISA). This test has proved to be both highly sensitive and highly specific and has continued to be used until the present time. As a national scheme it involves some degree of co-operation between practising veterinarians, the various goat breeders' groups and goat farmers as well as the Ministry of Agriculture and Fisheries who are responsible for administering the scheme. Results to date indicate that a large number of flocks have gained accreditation but a number of people who may be regarded as commercial growers are seeking a second tier scheme to limit the disease within their flocks without achieving accreditation.

Quantitative risk assessment and cost-effectiveness: two important requirements for meat inspection programmes - Hathaway SC; McKenzie AI (Proceedings of the New Zealand Society of Animal Production, 1987)
Lines of 40 ram lambs of a variety of breeds from 22 farms in Canterbury, and initially weighing between 32 and 40 kg live weight, were assembled on a farm and compared for growth rate and lean carcass gain during 12 weeks. High quality legume dominant pastures were used and changes in carcass measurements obtained from samples of lambs slaughtered at the start and end of the trial. Average growth rates and rates of lean carcass gain among lines ranged from 143 to 252 g/d and 27 to 53 g/d respectively. Lines of specialist meat and short-wool breeds (Suffolk-cross, Perendale and Dorset) had higher average gains than long-wool breeds (Corriedale, Coopworth and Romney). The long-wool breeds showed greater variation in fat measurement GR (S.D.

Reproductive performance of progeny of prolific Romney, Coopworth and Perendale sheep - Davis GH; McEwan JC; Howarth MV; Kelly RW; Paterson AT (Proceedings of the New Zealand Society of Animal Production, 1987)
Production data was collected from 400 mix4ded-age breeding ewes on each of 4 farms in the Kaiwaka area for 3 years between 1982 and 1986. Half of the ewes on each farm were shorn once yearly and half twice yearly. Each farm had a different time schedule. The once-yearly shorn group were shorn in either February, June, October or November and the twice-yearly shorn group in October and February, December and June, February and October or May and November respectively. Ewes second shorn in February were heavier at main shearing in October than twice-shorn ewes. Ewe live weight on the other 3 farms was unaffected by shearing treatment. Total clean wool production of twice shorn ewes was greater than once-shorn ewes on all farms with the effect being greater following second shearing in May and October. Mean staple length of the lines of fleece wool reflected the actual interval between shearings and the seasonal wool growth cycle. Mean fibre diameter was a direct reflection of the seasonal wool growth cycle. Once-shorn wools were more discoloured than twice-shorn wools. Wools shorn between May and October were less discoloured than wools shorn between November and February. Frequency of shearing did not affect ewe survival, reproduction rate or lamb weaning weight. Average net wool returns were greater for once-shorn ewes on all farms.

Salmon farming in New Zealand - Todd PR (Proceedings of the New Zealand Society of Animal Production, 1987)
Romney ewes were used for a 2 x 2 factorial trial, 2 injections (boosted) v 1 injection of Fecundin(r) pre-artificial insemination (AI) x controlled internal drug releaser (CIDR) re-insertion v no CIDR reinsertion post-AI. The ewes were all synchronised with CIDRs for the AI carried out intravaginally without a speculum 52 h after CIDR withdrawal. Those ewes failing to conceive to AI were naturally mated at the next oestrus. Fecundin(r) boosting decreased the percentage of CIDR synchronised ewes becoming pregnant to AI (12.6 v 21.3, P<0.01) but increased multiple pregnancy rate (50.4 v 30.2, P<0.001) at the subsequent natural mating. Reinsertion of CIDRs for 5 to 8 d, 9 to 12 d after removal of the first CIDR had no effect on pregnancy rate to AI. The response to Fecundin(r) boosting in terms of multiple pregnancy rate at the natural mating was essentially the same in light ewes as in heavy ewes.

Some effects of injecting a prostaglandin F2 alpha (Lutalyse) during the post-partum period on the subsequent fertility of dairy cows - Macmillan KL; Day AM; Taufa VK; Henderson HV; Allison PA (Proceedings of the New Zealand Society of Animal Production, 1987)
The need to determine the scientific base and cost-effectiveness of traditional inspection methods is particularly important in New Zealand, a major exporter of sheep meat. Risk assessment as applied to potential human health hazards in a broad sphere can also be adapted to risk associated with a meat inspection programme. Risk associated with an export inspection programme aimed at maintaining market access must include human health, animal health and aesthetic defects. A quantitative risk assessment model is described for 2 different inspection methods for liver fluke (Fasciola hepatica) in adult sheep. Unless sensitivity and specificity data are produced, quantitative risk assessments are statistically invalid. Determination of specificity also allows cost-benefit analyses to be correctly performed.

The timing of CIDR withdrawal and ram introduction on ewe fertility - McMillan WH (Proceedings of the New Zealand Society of Animal Production, 1987)
If predictions for future growth of New Zealand's exports of chilled lamb meat are to be fulfilled, overall quality will have to be maintained at a consistently high level, and properties like storage life and appearance will require emphasis. A review of scientific literature showed that a wide range of farm practices can influence meat quality. The trend to breed leaner lambs, to slaughter more ram lambs at heavier weights and older ages in winter and spring, and effects of stressful experiences before slaughter, were seen as areas of potential concern for the production of high quality meat. However, it has not been established that these factors are of economic importance to the meat industry. It is suggested that they should be investigated as possible constraints on the future development of markets for premium quality lamb.

Trends in monthly milkfat production of cows in seasonal dairy herds in New Zealand - Macmillan KL; Henderson HV (Proceedings of the New Zealand Society of Animal Production, 1987)
Changes in shape of the femur and the m. semitendinosus occurring with developmental growth are described. It is shown that three-quarters of growth in muscle volume is consequent upon growth in length of bone, while shape changes in muscle account for only one quarter of growth in muscle volume. Attention to the role of bone is necessary in studies of muscle protein synthesis and muscle growth.

The use of a pastoral computer model - a learning experience - Ridler BJ; Stachurski LJ; Brookes IM; Holmes CW (Proceedings of the New Zealand Society of Animal Production, 1987)
Records from cows in herds which were production tested by the Auckland and Taranaki Livestock Improvement Associations from 1960 to 1984 were used in regression analyses to estimate trends in milkfat (mfat) production each month from August to May. The average annual increase in production was 0.84 kg mfat/cow in Auckland compared to 0.75 in Taranaki. This meant that over the period from 1960 to 1984, the estimated increases in production were 20.2 and 18.0 kg mfat/cow in Auckland and Taranaki respectively. In Auckland 14.2 kg of this increase occurred in September, October and November. The increase in Taranaki in these 3 months was 10.6 kg mfat/cow. Annual increases in production per cow would be greater if the rate of decline in daily production during summer (from December to February) could be reduced. No consistent increases in production have occurred during the autumn because of highly variable seasonal factors.

Advancement of breeding in non-lactating adult red deer hinds - Moore GH; Cowie GM (Proceedings of the New Zealand Society of Animal Production, 1986)
No abstract supplied

Artificial insemination in sheep - comparison of storage time, dose rate and insemination technique - Harvey TG; Johnson DL; Baker RL; Trust BK; Thomson BC (Proceedings of the New Zealand Society of Animal Production, 1986)
In 1984 selected Oxford Down (O) and Texel (T) sheep in Denmark and T and Finnish Landrace (F) sheep in Finland were purchased or leased and then assembled for treatment. The ewes were synchronised and superovulated before being subjected to surgical embryo recovery. Recovered embryos with at least 8 cells and intact zona pellucida were then deep frozen. The mean ovulation rate, number of eggs recovered and embryos frozen from the O and T in Denmark were 5.4, 4.4, 1.5 and 7.1, 5.0 and 3.0, respectively. Results for T and F in Finland were 7.5, 4.9, 4.1 and 10.0, 7.0 and 5.8, respectively. A total of 548 embryos was imported into New Zealand. Two-hundred and twenty embryos were thawed and transferred to Coopworth recipients in March and 46 in May 1985. The percentages of embryos surviving to term for the various breeds in March and May were: Denmark 0, 43 and 20; Denmark T, 59 and 7; Finland T, 59 and 55; Finland F, 64 and 50, respectively. Thirty-two Coopworths were inseminated with thawed F sperm deposited via endoscopy and 24 (75%) lambed producing 28 lambs. The importation of both embryos and semen was very successful.

Benefits and incentives available from objective measurement - Wiggins LK (Proceedings of the New Zealand Society of Animal Production, 1986)
No abstract supplied

Calving date effects on beef cow productivity - Smeaton DC; McCall DG; Clayton JB; Dow BW (Proceedings of the New Zealand Society of Animal Production, 1986)
An agonist of gonadotrophin releasing hormone (GnRH) improves dairy cow pregnancy rates when injected at an appropriate stage after insemination. These studies were extended to ewes and hoggets in a series of trials to determine the effects of a single injection of GnRH made at varied intervals after mating. All sheep were mated at a synchronised oestrus (day of oestrus = day 0) with treated ewes being injected on a set date with 2 or 4

The cause of reproductive loss in Gisborne-East Coast ewe flocks - Jagusch KT; Gray MM; MacLean KS; Towers NR; di Menna ME; McMillan WH (Proceedings of the New Zealand Society of Animal Production, 1986)
The relationship between lamb growth rate and ewe milk yield was examined using 213 ewe-lamb sets in 6 experiments. Factors included ewe breed, lamb rearing status, herbage allowance, lambing date and season. Lamb growth and ewe milk production were greater for twin- than single- lamb groups, for Dorset than Romney ewe breeds and for late than early lambing dates. Ewe live weight showed the reverse trend. Regression parameters indicated lamb growth rate was generally more dependent on milk supply during the first 6 than during 12 weeks of lactation. The exception was Romney ewes with low milk production rearing twin lambs. Comparisons among groups of regression coefficients and nominal ordinates (i.e. growth rate at low milk yield) showed that twin lambs were proportionately more dependent on pasture for growth than singles as were lambs reared by Romney compared with Dorset ewes. Similarly, a high herbage allowance, good seasonal pasture growth and a late lambing date caused a greater contribution of pasture to lamb growth. However, among groups there was much variability in the relationship and generally lamb live-weight gain was a poor indicating of ewe milk yield (approx. r

Comparison of autumn/winter with spring pasture for growing beef cattle - Reid TC (Proceedings of the New Zealand Society of Animal Production, 1986)
Ovine FSH was administered hourly to ewes for 48 h from the initiation of luteolysis. The mean ovulation rates of ewes receiving 2.5

A comparison of rams from fleece weight-selected and randomly bred Romney flocks for intake, wool growth and feed utilisation - McClelland LA; Blair HT; Wickham GA; Brookes IM (Proceedings of the New Zealand Society of Animal Production, 1986)
Trials undertaken at Rotomahana in 1984 and 1985 examined factors involved in sheep AI and provided a link between Rotomahana and a commercial AI programme. Semen collected and diluted by the New Zealand Dairy Board gave similar conception rates (46%) to semen collected at Rotomahana (42%). Results in 1984 indicated that there was a small but non-significant decrease in conception rate with semen storage time up to 15 hours (5 h 68%, 10 h 61%, 15 h 57%). In 1985 there was a highly significant difference between 5 and 20 h storage (46% v 25%) and this result was consistent over ewe ages and dose rate. In 1985, 200x10 6 sperm dose was compared to 100x10 6 dose in 3 subtrials. The overall conception rates were 45.7% and 37.5% respectively (P<0.05). In 1984 diluted semen stored in glass and inseminated using a fine glass pipette gave a higher, but not significant, conception rate than semen stored in mini straws and inseminated using a standard cattle pistollet (66% v 58%). In 1985 all semen was stored in glass and inseminated with either a glass pipette (conception rate of 49.8%) or a cattle pistollet (43.2%). This difference was non-significant, although there was a significant interaction of insemination equipment with dose rate. A significantly higher conception rate was achieved for cervical (52.8%) than blind insemination (29%) when ewes were inseminated 'on time' in 1985 and this effect was consistent over dose rate. There was no difference in conception rate when 'on-oestrus' insemination was compared to 'on-time' (63% v 61%). All first-order interactions among the effects of storage time, insemination method and 'on-oestrus' v ' on-time' were non-significant in the 1984 trial.

The consequence for feed dry matter intake of grazing sheep, cattle and goats to the same residual herbage mass - Collins HA; Nicol AM (Proceedings of the New Zealand Society of Animal Production, 1986)
On 6 Taranaki hill country farms, the effect of herbage mass and composition on the growth of lambs from birth to weaning was studied. On each farm 2 representative paddocks were selected and set-stocked with ewes from before lambing to weaning. Ewes and lambs were weighed at docking (early October), mid-November and at weaning in mid-December. Pastures were assessed fortnightly for herbage mass and composition. From docking to mid-November, no association between herbage mass and live-weight gain was found. The only factor influencing live-weight gain of ewes and lambs over this period was the percentage of green leaf material in the pasture. However, the live-weight gains of ewes and lambs from mid-November to weaning were negatively correlated with total herbage mass at lambing. Also over this period, live-weight gains of ewes were positively correlated with percentage of green, and negatively correlated with the percentage of stem, in pasture. With increasing levels of herbage mass at lambing there was associated decline in the percentage of green and increase in the percentage of stem in pastures over the mid-November to weaning period. Despite a large variation in stocking (11 to 26 su/ha) no relationship between stocking rate and live-weight gain of ewes or lambs was found. However, the total live-weight of lambs weaned/ha was correlated with stocking rate. The relationships established between pasture parameters and animal performance and between live weight of lambs weaned/ha and stocking rate indicate that higher spring stocking rates in Taranaki hill country than are presently adopted may decrease herbage mass at lambing thereby increasing the proportion of green herbage which will improve lamb growth and overall production/ha.

Consideration of alternative lamb drafting strategies - Garrick DJ; Purchas RW; Morris ST (Proceedings of the New Zealand Society of Animal Production, 1986)
The saleable meat, bone and trimmed fat content was measured on the sides of 643 steer, 273 heifer and 1086 bull carcasses. Saleable meat yield declined from approximately 70% in grade M to 59% in grade T for steers and heifers, while fat trim increased from approximately 8% in grade M to 25% in grade T. Carcass saleable meat yield in bulls was almost constant (72.6

Development of an effective goat embryo transfer regime - Tervit HR; Goold PG; McKenzie RD (Proceedings of the New Zealand Society of Animal Production, 1986)
Low lambing rates are characteristic of ewe flocks on the summer-dry East Coast. In the present experiment, groups of 4- and 6- tooth 54 kg ewes were either kept on, or transferred between, non-facial eczema-prone (NFE) and facial eczema-prone (FE) stations. Two additional groups on the FE station received weekly dozes of zinc and serial blood sampling of all groups identified ewes with a high threshold resistance to FE. Ewes gained 4 kg in the 8 weeks prior to mating. Groups on the NFE station had 3% barrenness and 55% twinning; those on the FE station had 18% and 38%. Resistance to FE reduced barrenness from 18 to 10% but did not increase twinning. Estimated lambing percentages were 150 on the NFE station, 113 on the FE. The FE factor was associated with some of the barrenness but most of the reproductive loss appeared due to a factor which imitated an oestrogen. The oestrogenic mycotoxin zearalenone, produced by some pasture Fusaria, was detected in pasture samples collected from the FE but not from the NFE station.

Early induction of ovulation in yearling red deer hinds - Fisher MW; Fennessy PF; Suttie JM; Corson ID; Pearse AJT; Davis GH; Johnstone PD (Proceedings of the New Zealand Society of Animal Production, 1986)
No abstract supplied

The effect of different protein/energy intakes on nutritional and physiological parameters in young sheep - Waghorn GC (Proceedings of the New Zealand Society of Animal Production, 1986)
Five Poll Dorset breeders have co-operated since 1982 in a progeny-testing programme to improve lean meat production in their respective flocks. Ram lambs were selected from each flock on their BV's for weaning weight (in 4 of the 5 flocks) and were then assessed for fatness (visually and tactually initially, and finally by ultrasonic probe), structural soundness, and muscling. The ram lambs selected for the progeny test were mated at random to Coopworth mixed-aged ewes on a commercial prime lamb property. The progeny were identified to sire and dam and their birthrank indicated by ear-tag. Only progeny born during a 6- to 7-day period were identified in this way. At slaughter in November, information on export grade, carcass weight, and GR measurement was obtained. Heritabilities of carcass weight (CWT) and GR measurement adjusted for carcass weight (AGR) were respectively 0.20 and 0.29 and the genetic correlation between them was -0.09 (based on 29 sires and 490 progeny). To rank the sires, data were analysed on 3 criteria: AGR: carcass lean index (CLI); and a selection index (SI) which included estimates of the relative economic values of carcass weight and GR measurement. Use of CLI was expected to produce the greatest gain in CWT, but least reduction in GR while AGR gave the largest reduction in GR but little gain in CWT. Use of SI would result in intermediate gains in both traits and would achieve the highest increase in financial return carcass.

The effect of dose level of steroid immunogen on the reproductive performance of ewes - Smith JF; McGowan LT (Proceedings of the New Zealand Society of Animal Production, 1986)
Red deer comprise over 80% of New Zealand farmed deer. The larger body and antler weights and faster growth rate of wapiti, originating in North America, have encouraged many deer farmers to hybridise these animals with red deer. This study sought a biochemical marker in blood which could discriminate red deer, wapiti and F1 hybrids. Blood samples were taken from over 200 red deer, North American wapiti, and F1 hybrids. Haemolysed red blood cells were treated with potassium cyanide and subjected to isoelectric focusing (pH range 5 to 8). Starch gel electrophoresis was performed on untreated samples which were scored for both haemoglobin and superoxide dismutase. Haemoglobin from North American wapiti had a higher isoelectric point than that of red deer. Haemoglobin of all F1 hybrids tested showed a double banding pattern representing both parental types. All F1 hybrids were also heterozygous for superoxide dismutase, though this marker was not absolute. It correctly discriminated 95% of the animals tested. This blood test could be used to verify hybridisation in live deer sales, identify hybrids among captured deer, and select for wapiti if those traits are desired.

Effect of Fusarium culture and zearalenone on the reproductive performance of ewes - Smith JF; di Menna ME; McGowan LT (Proceedings of the New Zealand Society of Animal Production, 1986)
No abstract supplied.

The effect of post-ruminal infusion of protein or energy on the pathology of Trichostrongylus colubriformis infection and body - Bown MD; Poppi DP; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1986)
Fat and lean Coopworth ewes that were daughters of fat and lean rams were joined with rams from the Invermay lean and fat selection lines to study the effects of genotype (fat, lean) and mid-pregnancy feeding level on foetal weight and ewe carcass measurements at day 135 of gestation. Ewes offered a high level of feed during days 30 to 100 of gestation gained 3% while those on a low level lost 9% of their day 30 live weight. All ewes were offered the same level of feeding from day 100 until slaughter on day 135. Mid-pregnancy nutrition had no effect on foetal weight. Litter size had significant effects on foetal weight (single 4.56 kg, twin 3.99 kg, triplet 3.24 kg). The weight of foetuses of the lean genotype adjusted for litter size and nutrition was 270g heavier (P<0.01) than that of the fat genotype. The weight of placenta, and placentome number/foetus decreased with litter size and were associated significantly with foetal weight. Fat genotype, however, had no effect on placental weight or placentome number. Fat genotype of the ewe and foetus did not affect a number of foetal skeletal size parameters but influenced foetal weight despite ewe nutrition. Consequently it appears that this influence on foetal weight is independent on any effect of the placenta per se.

The effect of pre-natal nutrition and type of birth and rearing of lambs on vigour, temperature and weight at birth, and weight and survival at weaning - Moore RW; Miller CM; Lynch PR; Dow BW (Proceedings of the New Zealand Society of Animal Production, 1986)
Future increases in production efficiency of milk production from pasture will be brought about primarily by increasing the genetic potential of cows to produce milk solids, and by developing grazing systems which combine a high level of herbage utilisation/ha with high dry matter intakes. Grazing often under-utilises herbage in spring, which leads to a reduction in quantity and quality of herbage in summer and autumn with a consequent accelerated decline in cow performance. Higher grazing stocking rates in spring combined with the conservation of a greater pasture area for silage produces an improved pasture and provides additional forage for supplementation in summer and autumn. At present the amount and seasonability of milk production in New Zealand is dictated by pasture production. This gives large variations in production between and within years, and may not represent the most efficient way of using milk processing plant or of satisfying the market's needs. Consideration may have to be given to less rigid systems of production involving more flexibility in calving date and a greater use of conserved feed.

Effect on ovulation rate of increasing or decreasing ovarian exposure to follicle stimulating hormone during the preovulatory period - Henderson KM; Ellen RL; Savage LC; Ball K; McNatty KP (Proceedings of the New Zealand Society of Animal Production, 1986)
Yearling red deer hinds were treated to advance the time of the normal onset of ovulation so that mating and subsequent calving would occur about 1 month earlier than usual. All hinds, except for the untreated controls had 15 days of intravaginal progesterone treatment beginning on 28 February. At progesterone withdrawal hinds were either untreated, or given pregnant mare's serum gonadotrophin (PMS) or gonadotrophin-releasing hormone (GnRH). Stags were introduced on 14 March and the hinds laparoscoped 7 or 12 days later to record the presence or absence of an induced ovulation. Untreated hinds had a very low incidence of ovulation prior to the onset of the normal breeding season. While the use of progesterone alone marginally increased the number of hinds ovulating, PMS or GnRH treatment was generally necessary to induce ovulation. However, assessed from calving records, fertility at the induced ovulation was poor.

Effects of gonadotrophin releasing hormone (buserelin) on sheep fertility - McMillan WH; Knight TW; Macmillan KL (Proceedings of the New Zealand Society of Animal Production, 1986)
Teaser stags and progesterone-PMS treatments were used to advance the breeding season in non-lactating adult red deer hinds. In Experiment 1, 2 vasectomised stags were run with 39 hinds for 15 d prior to joining with entire stags. More teased hinds (20/39) calved early (11-20 November ) than group of non-teased hinds (5/42). In other experiments, laparoscopy revealed that progesterone + PMS treated hinds ovulated in mid February. Although calves were born as early as 10 October, indicating stags could successfully fertilise a hind in mid February, such treatment did not result in many hinds calving in October. It seems that the stag is sub-fertile in February. Calving dates of contiguous control hinds show that a large proportion were mated 18 to 25 d after the induced oestrus in treated hinds indicating red deer stags can have an effect similar to the 'ram effect'. Some hinds calving to the induced oestrus produced twins.

Effects of milkfat yield and conformation traits on retention for a second lactation of Friesian and Jersey-sired cows - Ahlborn-Breier G; Wickham BW (Proceedings of the New Zealand Society of Animal Production, 1986)
Data from mature ewes repeatedly re-immunised against androstenedione or oestrone in 3 trials at the Ruakura (Coopworths), Wairakei (Perendales) and Whatawhata (Romneys, Coo9pworths and Perendales) Animal Research Stations, were analysed to estimate the repeatability of ovulation rate and number of lambs born per ewe. Immunisation responses were within the range of those reported previously (Smith, 1985). Between-year repeatability estimates were on average similar for immunised and non-immunised ewes. The unweighted average of the estimate was 0.29 for ovulation rate and 0.009 for number of lambs born, consistent with published values. The results suggest that the joint contribution of genetic and permanent environmental sources of variation to phenotypic differences between animals is similar under both physiological states. The high repeatability of ovulation rate in comparison with number of lambs born supports other published indications of its possible value for improvement of reproductive rate through selection.

The effects of various factors on the relationship between lamb growth rate and ewe milk production - Geenty KG; Dyson CB (Proceedings of the New Zealand Society of Animal Production, 1986)
Lambs that had been reared at pasture till 6 months of age were transferred to barley-based diets fed in outdoor yards. Consumption of barley grain was measured daily during the first 4 weeks that it was fed. Highest consumption was achieved when grain was processed and introduced to lambs at pasture before they were transferred to the feedlot. Lambs that received these treatments consumed nearly 800 g/hd/d of barley (air dry weight) within 2 weeks and nearly 1200 g/hd/d within 4 weeks of its introduction. They gained live weight at over 150 g/hd/d during the first 7 weeks of barley feeding with minimal health problems.

An estimation of the dietary allowances of Cu, Zn, Fe, Mn and Se for single- and twin-bearing ewes - Grace ND (Proceedings of the New Zealand Society of Animal Production, 1986)
A model that simulates lamb growth and feed consumption and makes economic assessments on export carcass grading returns is described. It simulates a flock of lambs of specified weight and sex and then, using relationships between live weight, carcass weight and GR, derives grading profiles for various drafting strategies. The option of drafting on the basis of live weight has been compared with options based on GR estimates of high, average and poor accuracy. These drafting policies were evaluated on the basis of several alternative fixed endpoints including total feed consumption, carcass weight and carcass value. Generally results obtained when drafting on GR were better than those based on live weight alone when GR was measured with high accuracy and when carcass weights were high. This model could be useful in making a wide range of evaluations and comparisons other than those reported.

Evidence of genetic improvement in the Angus Breeding Scheme of the Department of Lands and Survey - Nicoll GB; Johnson DL (Proceedings of the New Zealand Society of Animal Production, 1986)
The relative importance of the currently recorded large number of descriptive conformation traits and of milkfat yield on retention for a second lactation of 6645 Friesian-sired and 5709 Jersey-sired heifers was examined. In a linear multiple regression model, the effect of heifers deviating from the 'normal' conformation for a certain trait on the retention rate was used as an indicator for the relative importance of the trait. Milkfat yield was by far the most important trait for both breeds. Only a small number of conformation traits describing udder and teats influenced the retention rate significantly. The farmer with Jersey cows appeared to consider more conformation traits as important than the owner of Friesian cows. The results suggest the inclusion of only the important conformation traits describing udder and teats as potential traits in the selection of profitable dairy cattle in New Zealand to retain a high genetic response for milkfat yield.

Further development of sheep recording in New Zealand - Callow CF; Clarke JN; Rae AL (Proceedings of the New Zealand Society of Animal Production, 1986)
Comparisons were made of ewe and lamb weaning weights under 2 lambing dates (6 August and 6 September) with ewes at 2 pre-lambing ewe live weights (52 and 64kg) on 2 levels of pre-lambing pasture mass (approximately 1000 and 400 kg DM/ha) in a 2

Genetic and environmental sources of variation in hogget fleece weight and live weight in Coopworth sheep - Warmington BG; Beatson PR (Proceedings of the New Zealand Society of Animal Production, 1986)
Production systems in France are variable with many localised and adapted breeds, spread among small flocks lambing at different times of the year. In these ways, specialised selection schemes of varying importance and complexity including those designed for improvement of milk production and for out-of-season breeding have been developed. Selection objectives for dairy production concentrate upon milk production with recent attention to total solids content. For meat sheep, lamb production per ewe is important for competitive efficiency. Number of lambs and maternal contribution to lamb survival and lamb growth during suckling are important for the suckling breeds in the South and the improved breeds in easier conditions in the North, the latter also receiving emphasis on later lamb growth and carcass quality. Selection programmes are highly organised nationally under the data- processing control of INRA and the national co-ordination of ITOVIC. Twenty Breed Promotion Committees (UPRA's), 77 Professional Advisory Organisations (EDE's) and 11 Data Processing Associations (CRI's) are involved with a well-structured relationship among them. Selection schemes use different tools to give emphasis to dissemination of genetic merit in addition to ranking animals for breeding worth. The National Recording Scheme provides the common essential ingredient for all schemes. Animal information embraces natural oestrus or induced oestrus, litter size and live weight of lambs. Maternal pedigree is always recorded at birth while paternal pedigree is known if single-sire natural mating or AI is used. Electronic development is being introduced to assist automated collection of live weights and early provision of on-farm flock summaries. AI is used to assist genetic improvement over about 200 000 ewes, mainly dairy breeds. It allows superior ewes to remain on farms - it is estimated that in this way Ai can increase genetic progress by up to 30%. AI also avoids the need for centralised progeny testing and assists the gene dissemination from superior rams. Nucleus flocks are promoted as centres of gene dissemination only for scarce breeds and for those with very small flock size. Rearing of rams in a central location gives breeding schemes greater control over gene dissemination and organisation of elite matings, especially through AI. Considerable emphasis is given to this aspect of the French breeding programme to ensure effective gene flow for production of the next generation of sires. Central testing stations are also used, mainly to evaluate young meat breed rams which are the progeny of elite matings for growth and carcass merit in a standard environment and as a baseline for live animal performance assessment. Not all the schemes use the same tools in the same way. Breeder commitment and co-operation is nevertheless an important ingredient of the effectiveness in each case.

Genetic variation in resistance or tolerance to internal nematode parasites in strains of sheep at Rotomahana - Watson TG; Baker RL; Harvey TG (Proceedings of the New Zealand Society of Animal Production, 1986)
Fifty-six pregnant Romney ewes grazing a ryegrass/white clover pasture were divided into 7 groups of 8 and slaughtered at days 62, 81, 100, 115, 125, 135 and 143 of gestation to remove the conceptus (uterine tissue and membranes, placental fluids and the foetus[es] and determine its total Cu, Zn, Fe, Mn and Se content. The uterus was also removed from 8 ewes just prior to mating. Half the ewes had twin foetuses. The daily rates of deposition of Cu, Zn, Fe, Mn and Se were calculated from the slope of the curves relating the gestational age with the net trace element content of the conceptus. The dietary allowance of Cu, Zn, Fe, Mn and Se for the pregnant ewe was then calculated from the daily deposition rates into the conceptus, determined from this study, and published data on the net requirements for maintenance, coefficients of absorption and DM intakes. The calculated dietary allowances (per kg DM) for single- and twin-bearing ewes, were 7.4 mg Cu, 24 mg Zn, 36 mg Fe, 30 mg Mn and 33

Haemoglobin type and prolificacy in Booroola sheep - Dratch PA; Allison AJ; Williams TL; Kyle B; Wyllie JG; Littlejohn RP (Proceedings of the New Zealand Society of Animal Production, 1986)
Groups of 33 Coopworth ewes were drenched with either 25mg zearalenone, <UI>Fusarium culture (containing 25mg zearalenone) or water (controls) daily for 10 days pre-mating commencing on day 7 of the cycle following oestrus synchronisation with CIDRs. Reproductive performance was markedly reduced in the ewes treated with zearalenone or the Fusarium culture, with only 9.1% and 15.6% of ewes yielding fertilised eggs compared to 57.6% of the control ewes. Treatment reduced the number of ewes ovulating although displaying oestrus. Treated groups had 46% of ewes anovular compared to 12% in the controls. The ovulation rate for those ewes ovulating was less in the treated ewes (1.55) than the controls (1.86). Treatment with zearalenone or FusariumM culture reduced the proportion of egg- yielding ewes that had fertilised eggs (27.3% and 55.5%) compared to the controls (100%). Treated ewes had a markedly longer duration of oestrus and it was evident from corpus luteum size that the oestrus-ovulation relationship had been disturbed.

Hogget oestrus synchronisation: a comparison of CIDR and sponges - McMillan WH (Proceedings of the New Zealand Society of Animal Production, 1986)
At 3 months of age, the ovaries of F+ Booroola lambs [i.e. those heterozygous for the fecundity (F) gene] were lighter (P<0.01) than those of ++ Booroola lambs (i.e. those without the F-gene) which were of similar age and body weight. However, the number of follicles (>/= 1 mm diam.) in the above F+ lambs was 1.5 fold greater (P<0.01) than that in the ++ lambs. In lambs of both genotypes, ovarian follicles were active in synthesising testosterone and oestradiol and of reaching diameters which were similar to those of preovulatory follicles in mature ewes. However, none of the ovaries showed evidence of recent ovulations. In Booroola ewes (4 to 8 years of age), the proportions of small ovarian follicles (0.5 to 1.0 mm diam.) that synthesised progesterone, androstenedione and oestradiol in culture were related (P<0.05) to genotype (homozygous, FF > F+ > ++ ewes). Also in the above ewes, follicles in the FF and F+ animals reached maturity at smaller diameters than in ++ animals, namely 3.4

Immunity to gastrointestinal nematode parasites in domestic stock with particular reference to sheep: A review - Watson TG (Proceedings of the New Zealand Society of Animal Production, 1986)
The effect of post-ruminal infusion of protein or energy on the pathology of Trichostrongylus colubriformis infection and body composition in lambs was investigated by a comparative slaughter experiment. Lambs infected with 3000 larvae/d were infused with casein (50.5 g crude protein/d; PI) or glucose (isocaloric with casein infusions; EI) or solvent/diluent (SI). Uninfected controls (C) were also infused with solvent/diluent. Mean live-weight gain

Implications of objective measurement for fleece tenderness research - Orwin DFG; Geenty KG (Proceedings of the New Zealand Society of Animal Production, 1986)
Two pen-feeding experiments were conducted on Romney rams from fleece weight-selected (FW) and control (C) flocks. In experiment 1, 12 yearling rams from each group were fed cut ryegrass/clover pasture ad libitum for 6 weeks. In experiment 2, 9 ram hoggets from each group were fed lucerne based diets in 3 periods (P1, P2, P3). Individual feeding in P1 was 1 kg/d protein-extracted lucerne; P2, 1 kg/d protein- extracted lucerne plus 0, 30 or 60 g/d formaldehyde-protected casein; P3, 1.4 kg/d chopped lucerne. No differences in intake or liveweight, and no consistent trends in dry matter digestibility were found. FW rams had consistently higher greasy wool growth, this difference increasing with higher intakes and casein feeding. Between rams, the regression of wool growth on intake was positive for FW rams and negative or near zero for C rams. FW rams had greater live-weight gain than C rams when fed chopped lucerne. Differences in wool growth between FW and C rams could not be directly attributed to intake.

Implications of objective measurement for sheep management - Sumner RMW; Hawker H (Proceedings of the New Zealand Society of Animal Production, 1986)
Fleeces from 2000 mixed age Merino ewes in each of 6 years were classed traditionally (i.e. by subjective assessment of fineness into 2 or 3 lines) or objectively (i.e. fleeces put into one line). Off-type fleeces (about 10%) which differed markedly from the bulk of the clip were excluded from all the lines. The fleeces from 800 to 1000 Merino hoggets in each of 6 years were also used in comparisons of traditional and objective classing. The fibre diameter of each objective (OCP) line was very similar to the weighted mean of the corresponding traditional (TP) lines. Clean auction prices for the OCP lines were 0.8% and 1.0% lower than the weighted means of the TP lines for the ewes and hoggets, respectively. Research in Australia has shown that there is no difference in the processing performance of traditionally or objectively classed lines of fleece wool. The optimum classing method is therefore determined solely by the relationship between price and diameter. Wools 21

Implications of objective measurement of wool for sheep breeding - Binnie DB; Elliott KH (Proceedings of the New Zealand Society of Animal Production, 1986)
Fleeces from 28 000 Romney ewe hoggets in 14 mobs on 7 farms were weighed. Within each mob the top 1% hogget fleece weight (High) and a random 1% (Random) were identified, midside sampled and weighed off-shears. Subsequently the top 0.6% on hogget fleece weight from each mob and a random 0.3% were transferred to Woodlands Research Station and managed as one flock for the next year. At hogget shearing (9 months fleece) the 14 High sub-groups had an average 1.08 kg higher fleece weights (greasy) and 0.83 kg higher clean fleece weights than the Random sub-groups. There was a close between sub-group relationship between greasy fleece weight and live weight with the High hoggets having 0.78 kg heavier fleeces at the same live weight. The High hogget sub-groups had a higher mean live weight (+3.9kg), fibre diameter (+2.7

The influence of sheep to cattle ratios in live-weight gain on pastures grazed to different levels in late spring-summer - McCall DG; Smeaton DC; Gibbison ML; McKay FJ; Hockey H-UP (Proceedings of the New Zealand Society of Animal Production, 1986)
A survey of 30 Wairarapa hill country farmers during 1983 investigated how management practices influenced sheep performance. Lamb growth rates between birth and weaning which ranged from 153 to 300 g/d, were most affected by lambing date and the use of N fertiliser. Pasture cover/SU at lambing was more often a limitation to high lamb growth rates on early lambing farms, but even on later lambing properties insufficient feed at lambing was common. Pasture cover/SU at lambing was most affected by ewe winter rotation length, the use of N fertiliser, stocking rate and stock policies which enabled winter stocking rates to be progressively reduced. Weighing of sheep was associated with the attainment of higher autumn live weights. A high proportion of farmers weighted (63%), but their knowledge of acceptable live weights was poor.

Inheritance of active and passive humoral immunity in ruminants - Hohenboken WD; Muggli NE; Berggren-Thomas PL; Norman LM (Proceedings of the New Zealand Society of Animal Production, 1986)
Gastrointestinal nematode parasitism is a major concern for animal health and productivity. Studies at Rotomahana Research Station are evaluating the potential of genetic selection of sheep with increased resistance and/or tolerance to parasitism. Progeny testing of 35 sires in 1984 and 20 of these again during 1985 to investigate strain and sire variation, as well as repeatability in faecal egg counts (FEC), revealed an average heritability estimate of 0.34

Inheritance of foot and jaw abnormalities in sheep - Baker RL; Clarke JN; Harvey TG; Meyer HH (Proceedings of the New Zealand Society of Animal Production, 1986)
There are a total of some 710 000 winterfed sheep in Iceland, all of which are of the native Iceland breed. The organisation of the breeding work is in the hands of the Agricultural Society of Iceland. Sheep recording schemes have a long-standing tradition in Iceland. There are 140 local associations recording about 200 000 ewes. The most important traits in Icelandic sheep breeding are fecundity of ewes and weaning weight of lambs, but conformation and wool quantity are also considered. Level of productivity is high. The use of AI is of great importance in the sheep breeding work. Nearly all the selection of lambs for replacement is within flocks and selection work must be undertaken during a few weeks in the autumn when the sheep are taken from mountain grazing.

Interpretation of objective measurements of wool by the manufacturer - Elliott KH (Proceedings of the New Zealand Society of Animal Production, 1986)
The implications for sheep breeding of objective measurement of the wool characteristics fibre diameter, medullation, length after carding, loose wool bulk, colour, and vegetable matter are discussed. For the purpose of this discussion breed differences are categorised into fine, medium, Romcross, higher-bulk, crimpy, lustrous, and medullated wool types

Lambing date, ewe live weight and pasture mass effects on ewe and lamb performance during lactation - McCall DG; Smeaton DC; Wadams TK; Gibbison ML (Proceedings of the New Zealand Society of Animal Production, 1986)
A series of 4 herbage allowance trials was conducted over 2 years with beef cattle on a well-drained site in Northland. Two trials were conducted in autumn/winter (April-July) and 2 in spring (October and November). Analysis of the data, for each seasonal period combined over the 2 years, showed large differences in the relationships between daily live- weight gain and herbage allowance between the 2 seasons. At the same allowance, beef cattle grew faster in spring than in autumn/winter. Relationships between allowance and daily live-weight gain were: Autumn/winter: LWG = 0.48-1.37* 0.65 allowance Spring: LWG = 1.09-2.82* 0.45 allowance These differences were not associated with differences in in vitro digestibility (70 to 78% in all trials) or N concentrations. Allowances required for maintenance were lower in spring than in autumn/winter and potential growth rates in spring approximately double those in autumn.

Live weights, fleece weights and wool characteristics of screened high fleece weight and randomly selected Romney ewe hoggets - Hawker H; Littlejohn RP (Proceedings of the New Zealand Society of Animal Production, 1986)
Trials between 1979 and 1984 with Angora or Saanen donors showed that synchronisation of oestrus with progesterone injections delayed oestrus compared with progestagen sponges and that this delay was associated with fewer follicles and increased egg recovery and fertilisation rates. Highest ovulation rates were achieved when FSH was injected instead of PMSG and when donors were Saanens rather than Angoras. Surgical egg recovery rates decreased in donors with prematurely regressing ovulations. The response of recipients (feral or Angora) to sponge treatment varied markedly between years. Recipient pregnancy rate and embryo survival both increased when recipients were surgically twinned rather than singled. The various trials have enabled the development of an effective transfer regime. This involves synchronising/superovulating donors with progesterone/FSH and twinning or tripleting of recipients. Under these conditions Angora and Saanen donors average respectively, 14.0 and 24.5 ovulations, 10.8 and 18.6 transferable embryos and 7.5 and 11.8 kids born to recipients.

Management practices and productive performance on hill country sheep farms - Parker WJ; Townsley RJ (Proceedings of the New Zealand Society of Animal Production, 1986)
Beef cows in New Zealand are traditionally calved in late winter so that calves will be as big as possible for the weaner sales. This can create spring pasture supply problems and may contribute to poor reproductive performance in many beef herds. Early (11 August) and late (25 September) calving have been compared in 2 trials run on steep hill country. Comparisons were made in self- contained farmlets between June and February under 2 grazing strategies (set-stocking and rotational grazing). Later calving reduced interval to first oestrus by 16 d in both trials and increased pregnancy rates by 4 to 6%. Late born calves grew at the same rate as early born calves in both trials (0.87 and 0.97 kg/d) and so were lighter at weaning at a fixed date. A rotational grazing strategy favoured cow performance, but set-stocking favoured calf weaning weight by 12 kg and 5 kg in the 2 trials. Later calving is likely to result in better reproductive performance in many hill country beef herds, but because calves will be lighter as weaners it would best suit systems where steers are currently retained and finished over 2 years or sold as store cattle at 18 months. The 18 month finishing policy will require earlier calving to maximise steer weight at sale time.

A marker for red deer - wapiti hybrids - Dratch PA (Proceedings of the New Zealand Society of Animal Production, 1986)
The importance of the objective measurement of 6 wool properties, namely mean fibre diameter, medullation, fibre length after carding, colour, bulk and vegetable matter content is discussed. The necessity of accounting for all these properties when determining wool price differentials or the suitability of a wool lot or blend for a particular end-use is emphasised. An assessment is made of the manufacturing consequences of unit changes in each property along with end-use suitability, based on textile technology knowledge. This is supported by prices for New Zealand wool, analysed with account taken of availability, end-use and textile properties.

New Zealand beef export carcass grading - Woods EG; Fowke PJ; Bass JJ; Butler-Hogg BW (Proceedings of the New Zealand Society of Animal Production, 1986)
Somatic cell counts are used widely in the dairy industry to provide information on subclinical mastitis and milk quality. The value of this information is related to the benefits that can be obtained by using the somatic cell concentration to predict the presence of mastitis, and to the reduction in somatic cell count concentration that can be achieved by selective breeding. In this study the reduction in somatic cell concentration that can be achieved by culling and breeding is calculated from data collected under New Zealand conditions. Selection against logarithm (natural log) somatic cell concentration, without any emphasis on milk production, results in an annual rate of genetic change in log cell concentration of less than 0.6%. This represents the maximum achievable rate of 10% on the basis of their log cell concentration alone is predicted to reduce log cell count in the next lactation by 0.05 (cell concentration change of 20 000/ml).

Observations on the effect of litter size, pregnancy nutrition and fat genotype on ewe and foetal parameters - Owens JL; Kyle B; Fennessy PF (Proceedings of the New Zealand Society of Animal Production, 1986)
Growth rates, carcass composition and management problems of "short scrotum" rams (made by elevating the testes to a position against the abdominal wall using rubber rings), wethers and entire male lambs were compared on a hill country property in northern Hawkes Bay. Of 3 groups of 65 Perendale lambs selected randomly at docking at about 4 weeks of age, 1 group was left entire, 1 was made short scrotum and the other was castrated. The lambs were weaned at about 10 weeks of age, separated from the main flock at about 14 weeks of age and thereafter kept as 1 flock until slaughter at 9 months of age. They were weighted every 6 weeks from 14 weeks of age. After the removal of 6 lambs from each group for detailed investigation at Massey University, the top 50 lambs from each group were slaughtered and their carcass characteristics recorded. Short scrotum rams showed management advantages over normal ram lambs. They were easier to handle, and avoided the works hygiene problem of dirty genitalia. Short scrotum rams had an overall live-weight advantage of 3kg over wether lambs. This was found not to be due to fat deposition, as short scrotum rams showed a significantly lower GR of 3.3mm, compared with normal rams (4.6mm) and wethers (6.2mm), as predicted by regression for lambs of 32kg live weight. There was no significant difference in carcass weight or dressing percentage between lambs of this live weight, although more normal rams and short scrotum rams fell into heavier grades than did the wether lambs. In detailed investigations on 6 lambs from each group, no differences were found in muscle:bone ratio or fat distribution between the groups. Short scrotum rams had very low fertility; 50 of 56 had no epididymal sperm reserves and 6 had extremely low sperm production. Most sperm from short scrotum rams were abnormal. Short scrotum rams had significantly lighter testes and epididymides than normal rams. Short scrotum rams had plasma LH levels intermediate to normal rams and wethers. Differences between entire and short scrotum rams in testosterone levels varied inconsistently

Organisation of sheep breeding in France - Bodin L; Flamant JC; Elsen JM (Proceedings of the New Zealand Society of Animal Production, 1986)
Grazing yearling steers with ewes between November and March led to improved ewe and steer live-weight gains compared to grazing them in mobs by themselves. This occurred on both steep and easy land, and on each of 3 grazing pressures; residuals of either 1200, 1700 or 2300 kg DM/ha with pre-grazing masses 1200kg DM/ha greater than residuals. Ewe live-weight gains were 56, 67 and 82 g/d where sheep/cattle ratios were 100/0, 80/20 and 60/40, on a stock unit basis. Steer live-weight gains were 0.65, 0.55 and 0.51 kg/d for the 80/20, 60/40 and 0/100 sheep/cattle ratio treatments. Associated with improved ewe and steer performance under mixed grazing on steep country was a decrease in the area of pasture rejected at 40% cattle stock units compared to 0% and 20% cattle (26% v 32%). On easy country, the amount of clover in the pasture increased by 5 and 19 percentage units at 40% and 100% cattle stock units respectively. The results suggested that between 20% and 40% cattle stock units in a mob may be needed to obtain high levels of ewe and steer live-weight gain in late spring-summer.

Ovarian follicular development in Booroola ewe lambs and in highly fecund Booroola ewes - McNatty KP; Lun S; Heath D; Hudson N; McDiarmid J; Ball K; Smith P; Henderson KM (Proceedings of the New Zealand Society of Animal Production, 1986)
Two hundred and thirty 5-year-old Romney ewes were synchronised with progestagen intravaginal sponges and injected with dexamethasone 142 or 143 days after the median mating day of the first and second cycles of oestrus. Seventy-one % of the lambs were born 30 to 50 h after injection. The ewes were offered 2 pasture allowances for the last 6 weeks of pregnancy (approximately 6 and 1 kg DM/ewe/d). Lambs were vigour scored (1 to 10) and probed for rectal temperature and ewe lambs were cross-fostered as soon as possible after birth in order to obtain a 2 4 factorial design incorporating birth type (single and twin) rearing types (single and twin), pre-natal nutrition of dam (high and low allowance), and pre-natal nutrition of foster dam (high and low allowance). Lambs born from high allowance ewes had higher rectal temperatures at birth than those born from low allowance ewes, and female lambs had higher rectal temperatures than male lambs. Single-born lambs scored higher on vigour than those born as multiples. Increasing vigour was associated with increasing birth weight for all lambs, but increasing temperature was associated with increasing birth weight only for male lambs. There were no effects of pre-natal nutrition on lamb growth either through the dam or foster dam. The effect of birth type on lamb live weight was significant to 9 weeks of age whereas the effect of rearing type was significant to 33 weeks. There were no significant birth type x rearing type interactions at any age.

Perinatal lamb losses on a group of commercial sheep farms in Central Canterbury - Gumbrell RC; Saville DJ (Proceedings of the New Zealand Society of Animal Production, 1986)
Voluntary consumption (VC) of wet feed and feed dry matter (DM) was measured indoors with sheep fed 3 ryegrass and 2 tall fescue cultivars at different stages of maturity. Increasing plant maturity, indicated by increasing proportion of stem and flowerhead and of neutral detergent fibre and cellulose contents, was associated with decreasing wet feed intakes. VC of wet feed was about 15% higher with ryegrass cultivars than tall fescue cultivars. VC of feed DM was positively correlated (r = 0.89) with forage DM content at all stages of forage maturity and over a wide range of forage DM contents (12 - 25% DM). VC of wet feed was not affected by changes in DM content so that with forage at the same stage of maturity DM intake was increased with an increase in forage DM content. Studies with rumen fistulated sheep showed 90% of cells in eating boli are ruptured during 1 h incubation in rumen fluid in vitro or in vivo. Also VC of immature and mature perennial ryegrass was not affected when a balloon containing 1.5 l water was placed in the rumen whereas VC of chaffed lucerne hay was significantly depressed. It is concluded that VC of fresh forage is limited by a mechanism regulating intake of wet feed, not feed DM, and that DM content may be an important factor limiting nutrient intake.

Prediction of changes in somatic cell counts due to culling and selection - Smit H; Wickham BW (Proceedings of the New Zealand Society of Animal Production, 1986)
Genetic variation of foot and jaw 'abnormalities' in ewe hoggets and ewes has been studied with several breeds and strains at the Rotomahana Research Station. Foot and digit placement, foot roll, pastern angle and degree of hoof growth were scored for all 4 feet of each sheep at 9 months, 18 months and 5 years of age. Teeth occlusion, measured as the distance in mm (+ or -) between the front surface of the central incisors and the anterior edge of the upper pad, was recorded at 18 months and 5 years of age. Differences in incidence of foot abnormalities at 18 months of age among 2251 ewe hoggets representing 6 Romney strains and Coopworth or Border Leicester x Romney crosses, were significant for all traits except foot roll and digit placement. Border Leicester cross hoggets had a lower incidence of foot placement, pastern angle and hoof growth abnormalities than straightbred Romneys or Coopworth crosses. In a separate trial, 602 Booroola Merino first cross hoggets out of Romney and Perendale ewes had a significantly higher incidence of foot abnormalities than 480 straightbred Romney or Perendale ewe hoggets for all traits recorded at 18 months of age except pastern angle. There were only small differences among Romney strains and among breeds and crosses for teeth occlusion. Paternal half sib heritability estimates of foot traits recorded at 9 months of age were low (less than 0.11) and non-significant except for hoof growth (0.18 to 0.29). Similar heritability estimates for hoof growth were found in 189 month ewe hoggets (0.14 to 0.27) with low to moderate estimates for the other foot traits (0.02 to 0.17), and teeth occlusion (0.13 to 0.25). Heritability estimates were similar in 5- year-old-ewes for foot traits (0.03 to 0.20) but increased with age for teeth occlusion (0.36). Correlations between foot traits recorded at 18 months and 5 years of age were low (0.08 to 0.25), but were higher for teeth occlusion (0.49). Foot abnormalities and teeth occlusion were not found to have significant effects on either hogget growth, wool production or ewe reproduction, live weight or wool production. It is concluded that undue culling emphasis in ewes or rams on teeth or feet abnormalities is not warranted and may be counter productive.

Prediction of ewe mutton carcass composition from carcass weight, GR and C measurements, and the Hennessy grading probe - Kirton AH; Feist CL; Duganzich DM (Proceedings of the New Zealand Society of Animal Production, 1986)
Fourteen herd-years of data, comprising a total of 2169 records, were obtained from beef heifers involved in the Ruakura Genetics Section's long term breeding trials. The contributions of breed-cross, weight selection , herd year, birth date and age of dam, to variation in live weight, proportion exhibiting oestrus and proportion pregnant were studied. For heifers reaching first oestrus by about 15 months of age, means ages and weights at puberty were also calculated. Later-born calves were younger and lighter at puberty than average. Younger dams produced heifer offspring which reached puberty when older but lighter than average. Breed and location differences were greater for proportions of heifers expressing oestrus before joining than for proportions pregnant. At Goudies, the proportion achieving oestrus among Jersey x Angus heifers was 0.72, Friesian-cross 0.61, Hereford x Angus 0.47, Hereford 0.38 and Angus 0.25. Corresponding proportions diagnosed pregnant after 8 weeks of mating were 0.83, 0.93, 0.83, 0.78 and 0.73. Where there were major feed shortages over an extended period between 5 and 15 months of age, live weights and pubertal age were more affected than pubertal weight. In contrast, long term weight selection increased pubertal weight by 11%, while pubertal age was little changed. Preliminary estimates of heritability for pubertal age and weight were 0.31

Preliminary investigation into factors affecting lamb growth from birth to weaning on Taranaki hill country - Thomson NA; Mace MJ; Wright LA; Bishell SM (Proceedings of the New Zealand Society of Animal Production, 1986)
The aim of the present study was to examine the influence of the ram on plasma FSH concentrations in progesterone-primed Romney ewes which were: (1) anoestrous; (2) devoid of ovaries; (3) or anoestrous but induced to ovulate by a pulsatile injection regimen of luteinising hormone (LH). The results showed that there was an abrupt fall in the mean FSH levels in anoestrous or LH-pulsed ewes at 1 hour after ram introduction and that this level of suppression (~40%) was maintained for ~22 hours in anoestrous ewes and for 12 hours in LH-pulsed ewes. Also, an FSH reduction (~20%) was observed in the ovariectomised ewes. In the anoestrous ewes, the FSH changes were observed without any associated oestrous or ovulatory behaviour. In the LH-pulsed group, all ewes showed oestrus and 75% produced normal corpora lutea. Collectively, the evidence suggests that when attempts are made to achieve fertile matings in hormone-treated anoestrous ewes, there may be advantages in delaying ram introduction until ~24 hours after progesterone withdrawal.

Progeny testing for lean meat production in the Poll Dorset breed - Barton RA; Pratt RM; Rae AL (Proceedings of the New Zealand Society of Animal Production, 1986)
The composition of the dressed carcasses of 54 mixed-breed ewes was predicted from their hot carcass weight (HCW), measurements C and GR, and carcass wall thickness taken on the left (GPL) and right (GPR) sides 13 cm from the mid-line between the 11th and 12th ribs with an electronic Hennessy grading probe. The right side of each carcass was dissected into fat, muscle and bone. Mean HCW was 25.4 kg, GR was 16.9 mm, C was 6.6 mm, GPL was 22.1 mm, GPR was 22.7 mm, dissectible fat was 32.4%, muscle was 52.4% and bone was 14.1%. Of the variation in carcass fat %, GPR accounted for 74% and GR for 78%. When combined with HCW, GPR accounted for 77% and Gr for 80%. This last value was not further increased by adding more variables. GPR accounted for 67% of the variation in carcass muscle % and GR for 68% of this variation. When combined with HCW these values increased to 71% and 73% respectively and were not further increased by adding more variables. GPR and GR were also the best predictors of percentage bone.

Ram-induced inhibition of plasma follicle-stimulating hormone (FSH) concentrations in anoestrous Romney ewes - McNatty KP; Hudson N; Gibb M; Ball K; Morrison L (Proceedings of the New Zealand Society of Animal Production, 1986)
A major constraint on the profitability of using 'Fecundin(r)' is the cost of treatment and one approach to this problem is to reduce the dose rate. In 1984 Coopworth ewes were allocated to 3 groups. One group was untreated (control) while the other 2 groups were injected twice with Fecundin. One treated group received a full dose (2ml) each time while the other group received a half dose (1ml) on both occasions. In 1985 the same ewes were roboosted with Fecundin(r). Control ewes remained untreated while ewes from each group in 1984 were boosted with either a half or full dose. In the first year, both immunised groups showed a substantial increase in ovulation rate over controls (2.45 full, 2.20 half and 1.86 control). The higher ovulation rate of full dose compared to half dose ewes did not result in more lambs born or weaned (lambs born/ewes joined were 1.68 full, 1.65 half and 1.35 control). In 1985 all 4 treatment groups had a higher ovulation rate (2.43) than the control (2.03 and there were no difference between immunisation treatments. A similar patter was seen in lambs born. Thus the cost of treatment can be halved by using a 1 ml dose of Fecundin(r) without a drop in the additional performance obtained.

Rationalised classing of fine wools - Andrews RN; Hawker H (Proceedings of the New Zealand Society of Animal Production, 1986)
Oestrus synchronisation in hoggets was compared using either polyurethane sponges containing progestagen or 9 mm diameter silicone elastomer CIDRs (controlled internal drug releasers) in 600 hoggets in 3 trials. CIDRs and sponges were removed after 12 days in late May and 200 IU PMSG given to hoggets in 2 of the trials. Hoggets in the third trial received 0 or 300 IU PMSG. Half of the hoggets were shorn 1 month prior to the 4-day joining with entire rams. The loss rate of CIDRs and sponges was low (2%). No hoggets mated in the first 24 hours after removal and most matings occurred during the second day. During the peak of mating, more CIDR-treated hoggets appeared to mate in 2 trials, but fewer in the third (28 v 44% P<0.01). By the end of the entire joining, there was little difference in total mated. Treatment with CIDRs or sponges did not affect ovarian activity. Pregnancy rates were unaffected by method of synchronisation in 2 trials and improved by CIDRs in the third (38 v 20% P<0.05). Shearing generally had no effect on reproductive performance. PMSG improve oestrous and ovarian activity, but did not affect pregnancy rate. CIDRs were an effective substitute for sponges in achieving synchronised pregnancies in hoggets. Low pregnancy rates limited the ability to fully capitalise on the benefits of synchronisation.

Reasons and strategy for the introduction of objective measurement of wool - Simpson WS (Proceedings of the New Zealand Society of Animal Production, 1986)
Management factors under the direct control of the wool grower which influence objectively measured wool characteristics are breed, age, sex, level of feeding, frequency and time of shearing, breeding status and control of disease. Choice of breed has the greatest overall effect on wool type and resultant price level. Within the prevailing price structure wool returns for each breed type are more influenced by quantity than shifts in objective characteristics because of short term management decisions. This has resulted in considerable emphasis by growers, advisers and researchers on maximising overall wool production. Of the flexible management decisions, level of feeding and frequency and time of shearing have the greatest effect on objective fleece characteristics important in manufacture. Objective measurement will provide an objective basis for payments to growers through a better understanding of the technical effects of changes in measured characteristics. This will result in clearer price signals for differential changes in fleece characteristics and improved product specification ensuring the long term viability of wool production.

Repeatability of reproductive performance following active immunisation of ewes - Clarke JN; Smith JF; Johnson DL (Proceedings of the New Zealand Society of Animal Production, 1986)
The New Zealand sheep industry has been supported by a national sheep recording scheme, Sheeplan, for nearly 20 years. Sheeplan is directed towards genetic improvement of the national sheep flock. Its personnel have recently prepared a plan for future development which aims to extend the scope of the scheme, the accuracy of selection decisions made and the flexibility and efficiency of the recording service. It is proposed that the improved scheme be developed under Sheeplan's existing organisation as a centralised recording scheme and that restructuring of the data storage and data processing system be undertaken to enable Sheeplan to develop the following specific areas: improved adjustments for non-genetic factors; greater breeding value accuracy; development of across-flock relationships among animals; extension of the Sheeplan database; establishment of an industry-wide database; improved operational efficiency; accommodation of electronic developments for data collection and transmission; provision of opportunities for data analysis; and improve documentation of the scheme. The estimated financial benefit of implementing the plan is a doubling of the annual return to the sheep industry, from $9.6 million from the current Sheeplan to $19.7 million. This is achieved through a 40% increase in accuracy of selection decisions; a 10% increase in Sheeplan membership; and a 30% increase in effective use of Sheeplan records.

Sheep breeding organisation and recording in Iceland - Johmundsson JV (Proceedings of the New Zealand Society of Animal Production, 1986)
Mixed grazing experiments require decisions on the equivalence or interchangeability of grazing species. Often equivalence is based on an assumption of the relative feed intake of the species concerned. Another approach is to equate the species in terms of the effect they have on the pasture e.g. removal of herbage mass. In this experiment the species response to given sward conditions was investigated by controlling the rate of disappearance of herbage mass so that the equivalence of the species in terms of intake was derived rather than assumed. An autumn/winter ryegrass/white clover sward was grazed separately by growing castrate cattle (320kg), sheep (28kg) and goats (17kg). Plot area and animal numbers were adjusted as necessary (on a daily basis) to achieve the same rate of dry matter (DM) disappearance for each species. The 2 rates of DM disappearance for each species were achieved over 4 and 10 days and were 522 (

The society - about attitudes and perspectives - Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1986)
One alternative to control of gastrointestinal nematode parasitism with anthelmintics may lie in genetic selection for resistance to infection and/or disease. Heritabilities for faecal egg count suggest that good selection responses can be achieved with Romney sires. Research must now identify markers that will accurately predict resistant and susceptible animals. To do this successfully, mechanisms associated with immune-competence, - tolerance and -expulsion and host resistance to these nematodes must be elucidated more fully. This review examines local and systemic humoral and cell-mediated immunities to some of the GI nematode parasites infecting sheep, goats and cattle, with emphasis to sheep. Additional literature is presented identifying some of the factors that may modify any responses; factors such as host nutrition, hormonal and reproductive status and genetics. The overwhelming conclusion must be that significant large voids exist in our understanding of the processes of immunity exerted by domestic stock to combat infection with nematode helminths. Furthermore much latitude has been taken describing and interpreting observations since many are postulated from studies involving laboratory host parasite models.

Some genetic and non-genetic effects on the first oestrus and pregnancy rate of beef heifers - Morris CA; Baker RL; Bennett GL (Proceedings of the New Zealand Society of Animal Production, 1986)
Hogget fleece weight (HFW) (n=10376) and live weight (HLW) records (n=5930) from a highly fecund Coopworth flock were analysed by least squares methods to obtain estimates of environmental effects, heritabilities and genetic and phenotypic correlations. Single-born ewe hoggets were 2.7kg heavier than twins and 4.0kg heavier than triplets, and HFW differences were 0.07kg and 0.13kg respectively. Single-born ram hoggets were 2.9kg heavier than twins and 4.3kg heavier than triplets, HFW differences being 0.04kg and 0.10kg, respectively. Ewe hoggets reared by 3, 4 and 5 year old dams were 0.7, 1.2 and 1.4kg heavier than those reared by 2 year old dams, and the corresponding estimates for ram hoggets were 0.6, 1.8 and 1.3kg. Dam age did not significantly affect HFW; linear regression coefficients of the traits on age were 0.003kgd-1 (ewes) and 0.006kgd (rams) for HFW, and 0.04kgd-1 and 0.08 kgd-1 for HLW. The regression of HFW and HLW was 0.02kgkg-1. Heritability estimates (from paternal half-sib analyses) for HFW were 0.52

A study of short scrotum, castrated and entire ram lambs - Probert AD; Davies AS (Proceedings of the New Zealand Society of Animal Production, 1986)
Evidence of genetic improvement in the Department of Lands and Survey's Angus Breeding Scheme (ABS) was examined. Data from the ABS project and from the pilot Angus Sire Reference Scheme (ASRS) were used to estimate genetic trend in weaning weight and yearling weight in the ABS nucleus by regressing sire group values on year of birth. Estimated genetic improvement in weaning and yearling weight used the ABS data were 1.6

Viability of frozen sheep embryos and semen imported from Europe - Tervit HR; Baker RL; Hoff-Jorgenson R; Lintukangas S; MacDiarmid SC; Rainio V (Proceedings of the New Zealand Society of Animal Production, 1986)
No abstract supplied

The application of a lean growth index in ram breeding flocks - Dodd CJ; Bennett GL; Purchas RW (Proceedings of the New Zealand Society of Animal Production, 1985)
Carcass composition is determined by the relative partitioning of metabolisable energy intake among protein, fat and heat. Protein deposition is the net difference between rates of protein synthesis and protein degradation in tissues; synthesis and degradation proceeding at rates several times that of deposition. Relatively small changes in rates of protein synthesis or degradation may result in relatively large changes in deposition. The energy cost of protein synthesis may reduce energy available for fat deposition. The manipulation of carcass fat content may be more readily achieved by increasing lean growth than reducing fat deposition. Development of accurate methods for measuring protein synthesis should facilitate understanding of the mechanisms by which lean animals are grown and the selection of growth promotants useful in the production of leaner carcasses.

Are rams necessary for the stimulation of anoestrous ewes with oestrous ewes? - Knight TW (Proceedings of the New Zealand Society of Animal Production, 1985)
A study in 1980 showed that rams from a high prolificacy flock (Waihora) were more successful than rams from a low prolificacy flock (Whatawhata fertility control) in fertilising ewes by copulation. In this study translational swimming speeds of ram sperm in caprogen at 39

Blood metabolites and infertility in dairy cows - Wilson GF; MacKenzie DDS; Holmes CW (Proceedings of the New Zealand Society of Animal Production, 1985)
Kallikrein-like enzyme (KE) activity has been detected in bovine saliva from the front of the mouth and from the cannulated mandibular gland. The maximal activity (39 mUnits ml-1) was present in secretions from the mandibular gland of cows stimulated with carbachol (parasympathomimetic). A lower activity (24 mUnits m-1) was obtained under isoprenaline (sympathomimetic) combined with carbachol stimulation. No detectable KE activity was present in parotid gland secretions. When tested for vasodilator activity in sheep, all samples tested were positive, but the greatest response was mandibular secretions collected under carbachol stimulation. Using purified salivary proteins, it was demonstrated that the KE activity was associated with bands 7 and 8, major proteins secreted by the mandibular gland.

Body energy changes and metabolisable energy requirements in growing and adult sheep at pasture - Geenty KG (Proceedings of the New Zealand Society of Animal Production, 1985)
The growth of lambs, herbage mass and pasture composition (pre- and post-grazing), were monitored from January to June 1984 on 3 farms carrying 12 to 13 su/ha in the Taranaki hill country. Live weight was measured monthly on a random 5% of each flock. Additional animals were treated with cobalt (vitamin B12), selenium or both to identify possible deficiencies of these elements. A 'preventative' drenching programme was adopted on each farm to control gastro-intestinal worms. Mean daily live-weight gain was low (49 to 74 g/lamb) and did not improve significantly as a result of selenium or vitamin B12 treatment. Faecal egg counts indicating significant worm burdens were recorded on 2 of the farms in autumn despite regular drenching. Pasture before grazing were characterised by a high herbage mass (>3000 kg DM/ha) and a low green leaf content (50 to 60%). Apparent utilisation of DM at a single grazing was low (14 to 24%) but utilisation of green leaf was higher (28 to 43%). Green stem and dead herbage were not utilised. Although no factor was clearly defined as limiting animal performance, it is felt that improvements could be made by more intensive grazing (so that young stock are presented with lower herbage mass of higher green leaf content) and by adopting a more effective drenching programme.

The calculation of a simple lean-growth index for young sheep - Purchas RW; Bennett GL; Dodd CJ (Proceedings of the New Zealand Society of Animal Production, 1985)
Display life of frozen lamb chops was unaffected by breed or sex. Chops shrink-wrapped in oxygen permeable film had a longer display life than those vacuum packaged in a film of low oxygen permeability. Chops cut from frozen loins, then packaged had a significantly longer display life than chops cut from chilled loins, packaged, and then frozen. Ram lamb chops had significantly higher pH values than those from wethers and ewes. Chops from Romney-cross lambs had lower pH values than those from Coopworth-cross and Perendale-cross lambs. Meat pH decreased slightly but significantly during storage.

Comparative dairy production of Jersey and Friesians - Bryant AM; Cook MAS; MacDonald KA (Proceedings of the New Zealand Society of Animal Production, 1985)
Reasons for a temporary infertility syndrome in pasture-fed dairy cows were sought. Low submission and conception rates in 35 mature Friesians (either of high or low breeding index) were associated with low plasma albumin and glucose concentrations at the commencement of mating and poor body condition prior to calving. Discriminant function analysis indicated that albumin concentration was the most important variable in the allocation of cows to "fertility" groupings. Breeding index and level of milk production were relatively unimportant. A disturbance in protein metabolism was implicated as the cause of the infertility syndrome. A concentrate supplement containing 19% crude protein, fed to monozygous twin cows at 1.4 kg/d for 3 weeks prior to mating led to a marked improvement in conception rate.

Comparative intake of digestible organic matter and water by sheep and goats - Alam MR; Poppi DP; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1985)
The diurnal pattern of grazing and of rumen fill was studied to assess whether the initiation and cessation of eating were associated with any particular level of rumen fill. Four wethers fitted with large rumen cannulae grazed Huia white clover or Matua prairie grass for 14 to 21 days. Animals grazed longer on the prairie grass than on the white clover (8.9 v 5.8 h). Major grazing periods were evident in the morning and afternoon, although the animals generally spent more of each hour in razing during the afternoon. Rumen fill (volume, wet weight and dry weight) showed diurnal patterns of change similar to the grazing pattern. The maximum level of rumen fill (9.5 and 7.0 g DM/kg live weight (W) on grass and clover respectively) was observed at the end of the afternoon grazing period and the minimum at 0900 h on the grass (5.2 g DM/kg W) and at 1300 h on the clover (3.9 g DM/kg W). The implication of these results is that the intake of these roughages is less than that which is physically possible if the animal ate consistently to its maximum fill.

Contract Summary - Smith JF (Proceedings of the New Zealand Society of Animal Production, 1985)
A predictive test for susceptibility to fleece yellowing, which has a high heritability (0.5), is described. In a flock of Corriedale ewes 2 lines, selected entirely on the basis of the predictive test, demonstrated predicted levels of fleece yellowness when conditions promoted high levels of discoloration. Assessed greasy and measured scoured wool yellowness were not highly correlated. The yellowness value of scoured wool of highly resistant (HR) fleeces was always low; that of highly susceptible (HS) fleeces was variable and often high. The yellowness value of HS fleeces increased on storage of greasy fleeces. There was a negative correlation between yield and susceptibility, which was not strong enough to use for predictive purposes. HR and HS Corriedale ewes, thoroughly washed and then housed to eliminate weather effects, showed striking differences in yield % (83 v 61), wax % (16 v 25) and suint % (5 v 29) respectively. Pilocarpine hydrochloride was administered to the housed sheep to determine whether fleece yellowing and related faults were caused by excessive sweating. Results are variable.

Diagnosis of foetal number in prolific sheep - Owens JL; Armstrong JR (Proceedings of the New Zealand Society of Animal Production, 1985)
Two experiments were designed to estimate the effects of paddock contour on lamb mortality between 1 and 4 d of age (Expt 1) and 5 and 28 d of age (Expt 2). In Expt 1, 153 lambs born to 2-year-old ewes lambing in easy contoured paddocks (<20

Differences among and within crossbred beef cow groups in body condition and live weight - Morris CA; Cullen NG; Carson PA; Morley GA (Proceedings of the New Zealand Society of Animal Production, 1985)
In April and May 1983 60 Merino x Romney ewes of known Booroola genotype (30 F+, 30++) were immunised against androstenedione. An equal number of contemporary ewes of the same breed type and Booroola genotype were run together as an untreated control. Ewes were joined with vasectomised rams and ovulation rates were measure 4 weeks after the booster injection and thereafter at 3 successive 17-day intervals. The immunised F+ ewes showed an initial ovulation rate response of 1.62 compared with F+ controls and the response had decreased to 0.17 at the fourth observation 51 days later. The immunised ++ ewes showed an initial response in ovulation rate of 0.29 which increased to 0.61 at the second observation and decreased to 0.12 at the fourth observation. The experiment was repeated with the same sheep in 1984. Half of the ewes immunised in 1983 were given a booster injection in December 1983 (early group) and the other half were boosted in May 1984 (late group). Control ewes remained untreated. The early F+ immunised ewes had an ovulation rate response of 1.93 in February and 6 months later in August the response was still 0.90. The early ++ immunised had an initial response of 0.33 which increased to 0.40 at the second observation and decreased to 0.9 in August. Late F+ and ++ immunised ewes had initial responses of 0.71 and 0.38 which declined to 0.52 and 0.05 respectively 51 days later. These results all show a consistently higher response to immunisation in F+ ewes. The F+ ewes immunised in December before the onset of the breeding season showed the highest initial response and 8 months after the booster vaccination a significant response was still evident. F+ ewes immunised during the breeding season (booster injection in May) showed a lower initial response and a lower subsequent response than F+ ewes immunised before the breeding season. The duration of the response could not be determined in these ewes because of the short period from boosting until the end of the season.

Display life of frozen lamb chops. Effect of breed, sex, packaging film and temperature at packaging - Moore VJ; Duganzich DM (Proceedings of the New Zealand Society of Animal Production, 1985)
Effects of shearing and restricted feeding on the weight and leanness of lamb carcasses were measured in 3 experiments. Changes in fat measurements were parallel to and consistent with changes in carcase weight except where shearing and restricted feeding were combined. The 2 treatments together resulted in carcasses about 1 mm GR leaner than expected for their weight. Shearing following by mild underfeeding was more effective than either procedure alone in reducing fat cover and may increase the market value of overfat lambs.

Diurnal patterns of rumen fill in grazing sheep - Thomson BC; Cruickshank GJ; Poppi DP; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1985)
Weaned lambs grazed areas of native tussock oversown with either lotus or a mixture of white and red clover for 2 consecutive 4-week periods in each of 2 years. The lambs selectively grazed introduced legume in the clover plots but not in the lotus plots. At herbage allowances at or below 2 kg DM/animal/d, there were no differences in live-weight gain (LWG) between lambs grazing areas oversown with either lotus or clover. At high allowances, LWG tended to be lower during the initial 4 weeks of grazing lotus (60 to 114 g/d) and to then increase to comparable values for lambs grazing areas oversown with clovers (140 g/d). Any depression of LWG could be minimised by "conditioning" lambs to lotus, and by management of companion grasses to keep them in the vegetative state. It was concluded that the initial period of lower LWG on lotus would not be a drawback if lotus was used as a maintenance-type feed for ewes in summer/autumn.

Does immunisation pay? - Scobie GM; Bircham JS (Proceedings of the New Zealand Society of Animal Production, 1985)
Selection objectives for wool characteristics are usually set by analysing past prices, considering the results of processing trials and trying to predict future changes. Deficiencies in the information for setting selection objectives were, until recently, the main problems in calculating selection weightings. The situation has largely been rectified and the major problem now is in translating the object into index weightings. Variation in the genetic parameters causes great variation in the indices and there are doubts about the accuracy of the estimates of genetic and environmental correlations available. Recently calculated objectives place more emphasis on fleece weight than earlier formulations. Bulk, colour, length, resistance to cotting and soundness (staple strength) seem sufficiently important to include in the objective but indexes calculated using present genetic parameters usually place little weight on them. The result is that the extra gains from including colour, cotting and soundness in the index will probably not compensate for the work involved. However inclusion of resistance to cotting and soundness in the objective leads to more attention to fleece weight in the index. Foreseeable changes in market conditions seem unlikely to change these conclusions but a different set of correlations or cost/benefit calculations might lead to modifications.

Effect of ewe live weight on the level of response to steroid immunisation - Smith JF; MacLean KS; McGowan LT; Potts IR (Proceedings of the New Zealand Society of Animal Production, 1985)
Immunisation has implications for genetic improvement programmes by influencing the intensity of selection, the amount and nature of genetic variation able to be exploited by selection, the accuracy of the selection process or by adding flexibility to animal husbandry that might otherwise be the objective of dynamic crossbreeding strategies. Since immunisation changes the reproductive rate of a flock there are consequential effects on the intensity of selection that is possible. Improving the effective lambing percentage from 120% to 140% can increase the intensity of selection of female replacements by about 19%. The improvement is less on the male side, the combined effect on genetic improvement in a ram-breeding flock of 400 ewes being about 6%. Alteration to the balance of physiological events may even serve to display genetic variation not otherwise available for selection. Good evidence is available that natural ovulation rate is a useful selection criterion for improvement in lamb production, but there is no direct evidence on the value of selection following immunisation of ewes to steroid hormones controlling reproduction. Indirect evidence for sheep that litter size responses to immunisation are essentially additive with respect to the effects of age of ewe, flushing treatment, breed and strain differences, suggests no major antagonisms with natural ovulation rate. Indirect evidence from mice is not so comforting - Land and Falconer's selection experiment for natural and PMS-induced ovulation rate gave an estimate of only 0.33 for the genetic correlation between these two traits, suggesting that they were largely independent genetically. Regardless of the true genetic situation for sheep it seems important that recording programmes recognise and adjust for the different distributions of ovulation rate and litter size under natural v immunised circumstances.

Effect of herbage allowance on the productive performance of lactating and non-lactating hoggets - McEwan JC; Mathieson CD; Hawker H (Proceedings of the New Zealand Society of Animal Production, 1985)
Techniques of real time ultra sound (ADR 2130), Toshiba Sonolayer-L SAL 22A) and radiography (DSIR X-ray) were assessed to determine the accuracy of identifying ewes carrying 3 or more lambs. Ewes were scanned between 62 and 75 days of gestation with ultra-sound and between 110 and 124 days with X-ray. There were 94.2% (ultra- sound) and 96.2% (X-ray) of ewes predicted to be carrying 3 or more lambs that actually lambed with 3 or more lambs. However, 21.1% (ultra-sound) and 8.4% (X-ray) of ewes which lambed with 3 or more lambs were predicted to lamb with<3 lambs. Because ultra-sonic diagnosis is carried out at an earlier stage of gestation it gives greater flexibility to apply nutritional management to ewes carrying 3 or more lambs in order to sustain foetal growth in these high litter sizes.

The effect of level of milk intake on growth rate and herbage intake of Friesian bull calves of high and low breeding index - Wang X-J; Brookes IM; Wilson GF (Proceedings of the New Zealand Society of Animal Production, 1985)
Protein (NAN) flow to the small intestine was measured in early- weaning ram lambs grazing pure swards of white clover (W), lucerne (L), ryegrass (R) and prairie grass (P) at high allowances. Lambs were weaned at 6 weeks of age and measurements made at 8 and 12 weeks of age. Live-weight gain (LWG) measured over 6 weeks after weaning was higher for lambs grazing on legumes (308

Effect of post-weaning and post-mating/post-weaning shearing on ewe performance - Sumner RMW; Willoughby LD (Proceedings of the New Zealand Society of Animal Production, 1985)
No abstract supplied

Effect of season of steroid immunisation and Booroola genotype on the level of duration of response in ovulation rate of ewes - Davis GH; Crosbie SF; Smith JF (Proceedings of the New Zealand Society of Animal Production, 1985)
A trial was conducted in 1984 to examine the effect of live weight on response to immunisation in 3 groups of 200 Coopworth ewes differentially fed from weaning in December to reach 3 live weights in March (40, 50 and 60 kg). Half of the ewes in each group were immunised with Fecundin(r) and further subdivided into 2 levels of nutrition (*1.5 v 3.4 kg DM/ewe/d) for 4 weeks prior to a synchronised mating. Ovulation rate (OR); percent ewes lambing to first cycle (CR); lambs born per ewe lambing (LB/EL); percentage ova wastage (PRMO); and lambs born per ewe joi9ned (LB/EJ) were determined. Immunisation had a significant effect on all parameters (OR= +0.56; CR= -7.6%; LB/EL= +0.37, PFMO +10.1%; LB/EJ= 0.25). Ewe mating weight significantly increased OR (+0.37), CR (+19.5%), LB/EL (+0.25) and LB/EJ (+0.34) but did not significantly influence ova wastage. Premating nutrition significantly increased OR (+0.23), LB/EL (+0.09) and PFMO (+8.9%), but not LB/EJ. The regressions on mean group mating weight of OR and LB/EL in first cycle showed similar slopes for the immunised and control ewes. Nutritionally induced differences in ewe mating weight therefore did not influence these responses to immunisation. The response to LB/EJ was greater in the heavier ewes and reflected the effects of live weight on conception rate and embryonic loss.

Effect of slope on lamb mortality - McMillan WH; Knight TW (Proceedings of the New Zealand Society of Animal Production, 1985)
In the 10 years since it was observed that immunisation of ewes against steroid hormones resulted in an increased ovulation rate, research has provided some understanding of the mechanism of immunoneutralisation and of the factors which influence or modify the immunological and physiological response of ewes. It has also led to the development of a commercial vaccine. The mechanism of action is still uncertain although several changes in the endocrine balance of the ewe may be involved. Active immunisation against a number of steroids has been shown to increase ovulation rate and with passive immunisation, a mixture of steroid antibodies produced the best result. One possible mechanism via a reduced negative feedback on the pituitary and increased gonadotrophin release has been recorded. Effects at the ovarian level influencing follicular atresia must be also considered. The initial attempts at the practical application of this technology were unsuccessful. Although ovulation rates were increased, fewer lambs were born per ewe joined due to problems of anoestrus and anovulation. From these data the relationship between antibody titre and response was established and alterations to the composition of the antigen and treatment schedule were developed to modify the antibody response. Factors such as ewe age, level of nutrition and breed had little effect on the response. The response to changes in nutrition and live weight appear to be additive to those of immunisation, as is the response to exogenous gonadotrophins (PMSG). The timing of treatment relative to mating appears to have some effect, with intervals of less than 21 days reducing the lambing response through a high proportion of barren ewes. However there has been considerable variation in the final response indicating a major effect of early embryonic mortality. Lamb birth rank distribution has been within the predicted range and been seen mainly as an increase in twins with some higher order multiples. The mortality of lambs from treated ewes has been similar to that of lambs of the same birth rank from untreated ewes. The growth and reproductive performance of the progeny from treated ewes has been unaffected.

Effect of steroid immunisation in the performance of 3 breeds of sheep under hill country conditions - Knight TW; Smith JF; Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 1985)
Forty Romney hoggets were immunised against oestrone during March. A similar number served as untreated controls. Half of each group was treated with progestagen sponges to induce oestrus. Their ovulation rates were determined 7 day after sponge withdrawal and in mated hoggets within 14 days of first oestrus. Half of the immunised ewes were boosted as 2- and 4-tooths, the balance receiving only a 4-tooth booster. Half of the untreated controls were first immunised as 4-tooths. Ovulation and lambing rates were recorded. Immunisation increased hogget multiple ovulation rates by 50%. Unboosted 2-tooth ewes had multiple birth rates and numbers of lambs born similar to untreated controls. Boosted 2-tooths had more multiple ovulations (37%), ewes lambing multiples (28%) and lambs born (28%) than control ewes. The ovulation rate of 4-tooth ewes was 2.24. Untreated control ewes had the lowest proportion of triple ovulating ewes (11%), with first treated 4-tooths and 4-tooths missing their 2-tooth booster intermediate (22%) and annually boosted 4-tooths highest (38%). Control 4-tooths lambed fewest multiples (53%), first treated 4-tooths were intermediate (63%) and 4-tooths missing their 2-tooth booster and annually boosted 4-tooths highest (75%). However, differences in 4- tooth ovulation and lambing responses were not significant. The limited data demonstrate that annual immunisation against oestrone can increase ovulation and lambing rates. Ewes missing an annual booster perform at levels similar to untreated control. Furthermore, the immunomemory system for oestrone appears to last for at least 24 months since the ewes gave birth to 189% of lambs compared to 194% in annually boosted ewes and 159% in untreated controls.

Effects of facial eczema on ewe reproduction and ewe and lamb live weights - Smeaton DC; Hockey H-UP; Towers NR (Proceedings of the New Zealand Society of Animal Production, 1985)
Because preliminary evidence indicated that shearing Romney ewe hoggets in early October increased wool growth in spring-summer but had little effect on live-weight gain, an experiment was designed to quantify the feed intake, live-weight gain and wool growth of shorn and woolly hoggets in spring-summer. The design was a 2 x 3 x 2 factorial, i.e. shorn v woolly hoggets (shorn at 4, 12 and 17 months of age v shorn at 4 and 17 months) x 3 herbage allowances (1.6, 3.2 or 4.8 kg total DM/hogget/d) x 2 replicates x 2 years. The 12 mobs, each comprising 15 hoggets, were shifted twice weekly for 18 weeks, with residual DM measured and intakes estimated at each shift. Live-weight gain (LWG) and wool growth were measured every 6 weeks from early October until mid February. There were no significant differences between the shorn and woolly hoggets in residual DM (and therefore in utilisation and intake) or in LWG. The shorn hoggets grew 1 g/d more clean wool during spring-summer, i.e. a total advantage of 0.2 kg greasy. LWG and wool growth increased curvilinearly with allowance. LWG's were greatest in October-November, while wool growth was greatest in January-February. Five shorn and 4 woolly hoggets were penned outdoors in close proximity to the grazing experiment and fed a pelleted diet ad lib. for the first 6 weeks after shearing in early October. Relative to the woolly hoggets the short hoggets ate 20% less in week 1, the same amount in week 2, and increasingly more from weeks 3 to 6 (30% difference in week 6). The results indicate that shearing in spring does not lead to significantly higher feed intakes nor to greater LWG's, although it does results in a modest increase in wool growth.

Effects of level of feeding at different times of the year on milk production by Friesian cows of high or low genetic merit - Holmes CW; Brookes IM; Ngarmsak S; Mitchell KD; Davey AWF (Proceedings of the New Zealand Society of Animal Production, 1985)
Udder volume (post milking) was determined in high and low breeding index (HBI;LBI) Jersey and Friesian cows. The difference in milk production of HBI and LBI Jersey herds (2 to 4 litres/day) was entirely attributable to difference in udder volume. This difference was generated during late pregnancy. Udder volume declined during lactation; 35 to 40% of udder volume at calving being lost by 20 weeks of lactation. There was no difference in udder volume between BHI and LBI Friesian cows measured at peak and in late lactation. Differences in production between these herds were due to increased udder productivity in the HBI animals (HBI, 2.0 litres/litre tissue/d; LBI 1.8 litres/litres tissue/d). Udder productivity in Friesians was 25% greater than in Jersey cows at peak and in late lactation. Milk yield and udder volume were significantly correlated (P<0.05) in Friesian and Jersey cows at all stages of lactation. Genetic selection of Friesian and Jersey cows has resulted in more productive animals in both breeds but through differing physiological mechanisms.

Effects of level of nutrition in winter and summer on the wool growth of Romney and Perendale ewes with a history of high or low winter wool growth - Hawker H; Crosbie SF (Proceedings of the New Zealand Society of Animal Production, 1985)
The active immune system involves phagocytic, cell mediated and humoral processes plus complement proteins, all interacting to protect the individual from pathogenic organisms. Passive immunity is acquired by new-born ungulates by ingestion of immunoglobulins from colostrum. Research in laboratory animals has established that peak antibody synthesis following challenge with a foreign antigen responds readily to directional selection. The increased titre frequently results in enhanced resistance to some diseases but enhanced susceptibility to others. Oregon State University research has produced conflicting results as to the heritability of the ability of new-born calves and lambs to acquire and absorb colostral immunoglobulins and as to the heritability of this passive immunity considered as a trait of the dam. Significant differences among breeds, selection lines and strains did exist for level of colostral immunoglobulins, and low levels (and, in one experiment, high levels as well) were associated with lower neonatal survival. In cattle, there was little evidence that either active immune response or level of complement protein C3 was heritable; but in ewes, the antibody titre to a challenge antigen was moderately to highly heritable. The authors speculate that stabilising selection for immune system traits might be most effective to improve generalised disease resistance and overall livestock production efficiency.

The effects of season on reproduction in beef cows - a review - Montgomery GW (Proceedings of the New Zealand Society of Animal Production, 1985)
The aim of this study was to examine the temporal relationships between FSH concentrations in blood and their effects on ovarian follicular viability, oestradiol synthesis and ovulation rates in Romney ewes. Collectively, the results showed that: (1) the number of non-atretic antral follicles (>/-1mm diameter) in sheep ovaries is influenced by plasma FSH concentrations; (2) the level of follicular oestradiol biosynthesis can be enhanced by FSH supplementation; and (3) sustained elevations of plasma FSH concentrations for 24 but not 6 h within 48 h of the onset of luteolysis significantly enhance the ovulation rate in Romney ewes.

Effects of shearing and herbage allowance on the intake, live weight gain and wool growth of Romney ewe hoggets in spring/summer - Hawker H; Crosbie SF; Barber M; Andrews RN (Proceedings of the New Zealand Society of Animal Production, 1985)
Previous work showed that nutrition during pregnancy substantially affected ewe live weight, but that subsequent effects on ewe and lamb survival and weaning weights were small. However, farm advisers have suggested that industry ewes suffer more weight loss than in the above trials with serious consequences for ewe and lamb survival. These problems were investigated in a trial involving 2 levels of nutrition in mid-pregnancy followed by 3 levels of nutrition in late pregnancy. Average conceptus-free live weights of the 6 groups at lambing ranged from 47.6 to 38.1 kg. The ewes had weighed 53 kg at the start of the trial. Ewes severely under-nourished throughout had an 86% survival during the trial period compared with 94% for the 5 better-fed groups. A line of ewes within the severely under-nourished group had, however, only 80% survival. There was a decline in the percentage of ewes lambing due to very nutrition in mid-pregnancy (78 v 85%). Similarly, lambing percentage of those ewes lambing was affected (126 v 142%). There was some effect on twin lamb survival. Birth weight, particularly twin lambs, was reduced by low nutrition but there was no effect on weaning weight.

Effects of varying feeding time on diurnal calving patterns in dairy cows - Macmillan KL; Pearce MG; Copeman PJA; MacDonald KA; Kilgour R (Proceedings of the New Zealand Society of Animal Production, 1985)
Season has important effects on reproduction in cows, although they may ovulate throughout the year. During winter, the effects of season delay puberty, prolong post-partum anoestrus and reduce fertility. There are seasonal differences in gonadotrophin secretion, pre-ovulatory follicular development and corpus luteum function. Furthermore, effects of season are more likely to be expressed when factors such as nutrition, age and lactation limit reproduction performance. Significant interactions occur between season and nutrition in the onset of puberty and the length of the post-partum anoestrous interval. In the pasture-based agricultural system in New Zealand, minimum feed supply occurs in winter when season depresses cow reproductive performance. A concentrated calving pattern is essential to improve feeding management and herd performance. To maintain a concentrated calving and high weaning percentage, calving date must be adjusted to reduce the effects of season and improve herd nutrition.

Effects of very low nutrition during pregnancy on live weight and survival of ewes and lambs - Smeaton DC; Wadams TK; Hockey H-UP (Proceedings of the New Zealand Society of Animal Production, 1985)
The relationship between maternal behaviour and ewe productivity was determined by least squares analyses of records for 1 year on 1050 ewes of 6 genotypes and 3 age groups. A 1 to 5 score was assigned to each ewe based on observations during tagging of lambs within 24 h of birth. Maternal behaviour was better (by 0.26 score) in 6-tooth (6th) than 4th ewes which had a score 0.27 units higher than 2th ewes. Maternal behaviour score increased by 0.18 for each unit increase in litter size (range 1 to 4). When the effect of litter size on maternal behaviour was removed, ewe genotype differences in maternal behaviour score were small. Lambs weaned/lambs born, corrected for litter size, age and genotype of ewe, increased by 0.06 for each unit increase in ewe behaviour score. The rate of increase was greater within high litter sizes. Weight of lamb weaned/ewe lambing was higher for ewes with higher scores for maternal behaviour.

Estimates of environmental effects and some genetic parameters for weaning weight and fleece weights of young Angora goats - Nicoll GB (Proceedings of the New Zealand Society of Animal Production, 1985)
Forty Romney and Perendale ewes with a history of either high (W+) or low (W-) winter wool growth but similar summer wool growth were selected from a large flock. The ewes were not pregnant and were penned individually indoors and offered either 500 or 1500 g/d of high quality pelleted diet for 8 weeks in both winter and summer. The 2 breeds had similar intakes and live-weight changes, but the Romneys grew more wool. The W+ and W- ewes had very similar intakes and live-weight changes. Intakes on the low and high plane of nutrition respectively were 420 and 1093 g DM/d in winter and 422 and 1222g DM/d in summer. Corresponding live-weight changes were -71 and +54 g/d in winter and -112 and +131 g/d in summer. Summer wool growth rates were on average twice those in winter. Plane of nutrition had a much greater absolute effect on wool growth in summer than in winter (5.5 v 2.3 g/d), but the relative effects were similar (54 v 48%). The W+ ewes grew 38% more wool in winter than the W- ewes (5.8 V 4.0 g/d) and had a 38% higher mean staple strength (2.7 v 1.8 g/tex). Differences between the W+ and W- ewes were similar on the high and low planes of nutrition, and also similar for the Romneys and Perendales. The variation in winter wool growth and hence in staple strength was evidently due to variation in the partitioning of nutrients to wool growth rather than to variation in feed intake.

Evaluation of by-product feedstuffs: acceptability to cattle and farm feeding procedures - Matthews LR; Kilgour R; Bremner KJ; Dawson J; Eden M (Proceedings of the New Zealand Society of Animal Production, 1985)
Metabolisable energy (ME) intake and body compositional and energy changes were measured in grazing lambs weaned at 4 or 12 weeks of age and in light or heavy ewes offered 3 herbage allowances during early lactation. Body energy change (MJ/kg) from 4 to 12 weeks of age varied markedly between early weaned (7.4) and suckled lambs (13.4) because of different rates of body fat deposition but was similar for both groups (16.4) from 12 to 24 weeks of age. Average efficiency of utilisation of ME for growth was 0.38 and maintenance energy requirement 0.691 MJ ME/kg W0.75/d. The ME intakes of lambs were considerably higher than those estimated using MAFF (1975) and ARC (1980) data, particularly between 4 and 12 weeks of age. The energy content of body weight loss (MJ/kg) was greater in light (60) than in heavy ewes (37) because of a higher proportion of fat in weight loss in light ewes. Absolute body energy loss (MJ/d) was lower in light (6.3) than in heavy ewes (7.9), but ME intake (MJ/d) and milk energy production (MJ/d) were similar for each class of ewe.

Ewe maternal behaviour score and lamb survival - O'Connor CE; Jay NP; Nicol AM; Beatson PR (Proceedings of the New Zealand Society of Animal Production, 1985)
Data on live weight (LW) and condition score (CS) were collected in a large scale breed evaluation at Goudies (Department of Lands and Survey, Rotorua). The LW data were obtained 4 times a year; the CS data on a 1 to 10 scale similar to the Ellinbank scale (10 fattest), were obtained on 7 occasions from April 1982 to February 1984. Seven breed groups, 5 2-breed crosses and 2 straightbreds (Angus and Herefords), were compared. The crosses were Hereford-Angus (HA, including its reciprocal), South Devon-Angus (Sd.A), Friesian-Angus (FA), Friesian- Hereford (FH) and Jersey-Angus (JA). Breed differences for LW and CS were reasonably consistent between years or seasons, in spite of large year effects and significant breed x age interactions. The CS means for JA, FA and FH were 0.9, 0.5 and 0.6 units less than for Angus cows, which in turn were 0.3 and 0.7 units lower than HA and Herefords respectively. The scores of Sd.A cows were near the average of the 7 groups together, but they were heaviest, being 22 kg above the herd mean. It is suggested on the basis of this evidence that using the same target for LW or CS for different breed crosses is unrealistic. Within breed and age groups, the correlation between August and November CS was 0.43. The equivalent figure for LW was 0.84. For each unit increase in CS, LW rose by 25.2 kg (r=0.53, range 0.42 to 0.60 on different recording occasions.

Exploitation of the sheep's genes - the Government contribution - Callow CF (Proceedings of the New Zealand Society of Animal Production, 1985)
Friesian cows of high (126) or low (104) breeding index (BI) were differentially fed during late gestation, early lactation and late lactation, and milkfat (MF) yield and condition score (CS) responses measured. In 40 cows fed to calve in either thin (CS=4) or fat (CS=5.3 in 1981; CS=6.0 in 1982) condition, a similar non-significant response to extra CS at calving was observed in both BI groups (3.0 to 8.6 kg extra MF/extra CS). For up to 4 weeks in early lactation, 24 and 32 cows in 1982 and 1983 respectively, were offered either restricted (12 to 15 kg DM/cow) or generous (50 kg DM/cow) daily allowances of pasture. Feed restriction reduced daily MF yields by 0.2 to 0.4 kg/cow, but subsequent production recovered rapidly. The extent of this recovery was less for cows of low than for cows of high BI in 1983 but not in 1982. In weeks 27 to 30 of lactation in 1983, 24 cows were offered either restricted (18 kg DM/cow) or generous (80 kg DM/cow) daily allowances of pasture. In weeks 28 to 31 of lactation in 1984, 32 cows were offered 30 kg pasture DM daily, either with or without a daily supplement of 5 kg of concentrates. Feed restriction reduced daily MF yields by a similar extent for both BI groups (0.2 to 0.3 kg MF/cow) and recovery during the final 6 weeks of lactation was similar for both groups.

Immunisation of ewes against steroids: A review - Smith JF (Proceedings of the New Zealand Society of Animal Production, 1985)
The first two years' (1983, 1984) results of a trial to determine the effect of immunisation with Fecundin(r) on the reproductive performance of Romney, Coopworth and Perendale ewes under hill country conditions are reported. Immunisation increased ovulation rate by 40 to 60%, lambs born/ewe present at lambing by 19 to 26% and lambs present at weaning by 4 to 9%. The major reason that the increased potential lamb production of the immunised ewes was not realised in practice was the failure of the ewes that lambed to produce as many lambs as expected from their measure ovulation rate. Immunisation tended to produce a larger increase in ovulation rate in Romneys than in Coopworth and Perendales and in older ewes than in younger. Lambs of immunised ewes had lower birth weights and higher mortality rates within each birth rank than lambs from non-immunised ewes.

Implications of steroid immunisation for programmes of genetic improvement of sheep - Clarke JN (Proceedings of the New Zealand Society of Animal Production, 1985)
No abstract supplied

The importance of protein turnover to metabolism and carcass composition of growing lambs - Schaefer AL; Davis SR; Hughson GA (Proceedings of the New Zealand Society of Animal Production, 1985)
A serial slaughter experiment was conducted with sheep under continuous growth and during realimentation following body weight stasis at c. 20kg for 56 days. Undernutrition resulted in negative protein and energy balance. Skeletal remodelling facilitated growth in linear dimensions while protein, water and ash decreased or remained unchanged in bone. Bone weight increases were solely attributable to large increases in bone fat. Protein appeared to be depleted in similar proportions from muscle, bone and the whole body. Realimentation resulted in a trend for compensatory growth of muscle mass relative to bone length and protein content. Within bone there was a trend for restoration of bone protein content rather than growth in bone length. Bone weight was inadequate in describing these phenomena.

Improved feedback of carcass information from freezing works to farms - Dodd CJ; Pownall MJ (Proceedings of the New Zealand Society of Animal Production, 1985)
A Sheeplan supplementary lean lamb option has been developed to assist in the selection of sheep for meat production. Output information includes a breeding value for fat-depth measurement "C" over the 'eye muscle' and a lean growth index (LGI), combing leanness with growth performance. Performance records, including live animal ultrasonic fat depth measurements and subjective assessments of fatness by lamb drafters were analysed on 1970 ram hoggets from 25 ram breeding flocks. The average mob live weight at assessment was 47.9 kg (range 34.2 to 60.3) associated with an average fat depth C of 3.3 mm (range 1.7 to 5.6). The subjective assessment of live-animal fat depth has the advantages of speed and simplicity but further work is required to develop the most appropriate calibration techniques. The extent of within-flock variability in the animal records was examined and comparisons made between 2 methods of adjusting fat depth for live weight within each flock. The calculation of within-flock fat- weight relationships for this adjustment was adopted for use in larger flocks, but a constant exponent method is preferred when flock size is small. The wide variation in the LGI within flocks suggests considerable opportunity exists to make worthwhile genetic progress in lean growth rates.

Influence of follicle stimulating hormone on ovarian follicular development and ovulation rate in Romney ewes - Hudson N; McNatty KP; Ball K; Gibb M; Heath D; Lun S; Kieboom L; Henderson KM (Proceedings of the New Zealand Society of Animal Production, 1985)
Levels of cell mediated immunity (CJMI) were monitored in pregnant and non-pregnant control ewes to assess the impact of pregnancy on CMI in sheep. Pregnant plasma caused a significant depression in lymphocyte culture reactivity with mitogens (PHA, Con A and PWM) or with antigen (BSA) in primed animals. No defect in transformation was evident in pregnant lymphocytes per se, which gave normal transformation when cultured in control plasma. Delayed- type hypersensitivity (DTH) responses to specific antigens were significantly lower during pregnancy in response to 1

The influence of the Beta2-adrenergic agonist, clenbuterol, on lipid metabolism and carcass composition of sheep - Thornton RF; Tune RK; Payne G; Larsen TW; Johnson GW; Hohenhaus MA (Proceedings of the New Zealand Society of Animal Production, 1985)
Three experiments involving a total of 7 forages ranging in N content from 6.6 to 26.8 kg DM were conducted to examine comparative ad libitum digestible organic matter intake (DOMI) in goats and sheep. Digestibility trials were conducted for 7 to 10 d during each trail when water consumption and rumen NH3N concentration were also monitored. DOMI in goats was higher than in sheep with forages of less than 0.6 OM digestibility (OMD). The relationship between the DOMI (g/kgW0.75/d) of goats and sheep was described as DOMI (goats) = 0.74 DOMI (sheep) + 10.6. The ratio of DOMI (goats)/DOMI (sheep) was greater than 1.15 for forages of OMD less than 0.6 and close to 1 for forages of OMD greater than 0.6. Goats maintained higher rumen NH3N concentration (109 mg NH3N/l). Of the 5 forages with OMD<0.6, 2 resulted in rumen NH3N>50 mg NH3N/l, considered the critical level for microbial digestion. The other 3 forages resulted in rumen NH3N<50mg NH3N/l (15 to 41 mg NH3N/l) in sheep whilst goats were able to maintain higher concentrations (43 to 60 mg NH3N/l). The ability of goats to maintain higher rumen NH3N with low N diets was associated with their lower water intake. The mean water intake of goats and sheep was 1884 and 2795 ml/kg DMI, respectively. It is concluded that goats have a greater DOMI than do sheep particularly when offered forages with OMD<0.6 and of low N content partly because of their ability to maintain higher rumen NH3N concentrations.

Inheritance of loose wool bulk in Romney and Perendale sheep - Bigham ML; Sumner RMW; Clarke JN; Johnson DL (Proceedings of the New Zealand Society of Animal Production, 1985)
Lifetime performance data were collected from flocks of 200 mixed-age Romney, Coopworth and Perendale ewes at Whatawhata Hill Country Research Station which were shorn either once yearly in November or twice yearly in May and November beginning in 1978, together with the lifetime performance data of 2-year-old replacement ewes entering these flocks in 1979 and 1980. Twice-shorn ewes were consistently heavier after shearing in November with an apparent carryover effect the following May. More of the twice- shorn ewes required dagging before shearing in November. There was a significant frequency-of-shearing x breed interaction for both total greasy and total clean wool production. Twice-shorn Romney and Perendale ewes grew more wool than once-shorn ewes. Wool growth of the Romney was greater following shearing in May compared with the other 2 breeds. Frequency of shearing did not affect ewe survival, number of lambs born, lamb survival, or weight of lamb weaned per ewe. Incidence of casting was insignificant. Average net wool returns were greater for once-shorn ewes.

Intake and duodenal protein flow in early weaned lambs grazing white clover, lucerne, ryegrass and prairie grass - Cruickshank GJ; Poppi DP; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1985)
Groups of animals were exposed to 1 of 8 by-product feedstuffs for 15 minutes daily. Each animal's consuming time was scored. Stable intakes occurred after intervals ranging from 2.3 d for whey permeate to 6.4 d for brewer's waste. Sulphuric acid whey and mother liquor were not accepted. Familiarising the animals with the pens and feeding procedures, and reducing social dominance effects resulted in increased consumption. Mixing a low preference feed in increasing proportions with a highly acceptable feed can result in cows eating previously rejected products. By this means cows were changed from concentrated deproteinised lucerne juice or corn steep liquor (highly acceptable) to mother liquor, brewer's waste or cheese whey (less acceptable) in from 5 to 15 days.

Leanness of lamb carcasses following restricted feeding and shearing - Bray AR; Moss RA; Burton RN; Taylor AG (Proceedings of the New Zealand Society of Animal Production, 1985)

Nutritional value of 'Grasslands Maku' lotus grown on low fertility soils - Lowther WL; Barry TN (Proceedings of the New Zealand Society of Animal Production, 1985)
Ingestion of the spores of Pithomyces chartarum by sheep causes liver injury with a resultant rise in the blood concentration of the liver enzyme, gamma glutamyl transferase (GGT). This paper collates results concerning the effects of facial eczema (as determined by GGT levels) from 2 trials carried out in the autumn of 1981. Wash counts of spores in pasture ranged from nil to 130 000 for 45 days in February- March. Levels of GGT were determined about 1 month later. Factors significantly associated with GGT levels included premating shearing, age, nutrition level (erratic response), and ewe selection line. High levels of GGT were associated with depressed ewe performance. For each 100 iu/l increase in GGT, ewe mating and subsequent weaning weights declined by up to 0.3 and 0.4 kg respectively. Litter birth and weaning weights declined by up to 0.15 and 0.6kg/100 iu. Similarly the proportions of ewes lambing and lambing multiples were reduced by up to 2.5%. For a modest outbreak of facial eczema causing a rise in GGT of 200 iu/l, the loss in weight of lambs weaned could be as high as 13%.

Ovulation and lambing responses with alternating steroid immunisation over 3 years - McMillan WH; Smith JF (Proceedings of the New Zealand Society of Animal Production, 1985)
Immunisation is a potentially profitable technique to improve ovine fecundity. It increases the proportion of multiple bearing ewes and lambs born as multiples. This calls for adequate feeding if production is to be sustained. The technique is therefore likely to have higher net returns in areas with ample summer feed. AS the response to the treatment is variable, the probability of not breaking even with the cost of the drug can be as high as 30%. Where feed is adequate additional net returns of $1 to $2 per ewe can be expected if the response is a 25% increase in lambs born per ewe joined.

A physiological basis of genetic improvement in milk production of Friesian and Jersey cows - Davis SR; Hughson GA; Bryant AM; MacKenzie DDS (Proceedings of the New Zealand Society of Animal Production, 1985)
Changes in rumen digesta and electrolyte composition were investigated in 4 high (HS) and 4 low (LS) bloat susceptible cows for 7.5 h following intraruminal loading with 10 litres water containing 0 (L), 1.76 (C), 3.52 (H) or 7.04 (HH) moles Na. Pre-treatment Na concentrations averaged 130 mmol/litre for both susceptibility groups, with increases averaging -20, 10,42 and 95 mmol/litre after addition of L, C, H and HH respectively. Susceptibility groups did not differ in rate of return of Na concentration toward pre-treatment values. Increasing Na loading decreased fluid loss from the rumen but LS cows consistently lost more fluid than HS cows, with no treatment- susceptibility interaction.

Prediction of lamb carcass composition from GR and carcass weight - Kirton AH; Duganzich DM; Feist CL; Bennett GL; Woods EG (Proceedings of the New Zealand Society of Animal Production, 1985)
A lean-growth index (LGI) incorporating growth rate and the proportion of that growth which is fat is calculated by first converting live-weight differences into differences in weight of lean tissue and then adjusting these values using an estimated breeding value for fat depth. The adjustment of fat depths for weight is by within-flock double-log regression or by specifying a constant exponent in the relationship between fat depth C and live weight. Simulation studies suggested that the constant-exponent method was superior for smaller groups of sheep. Improvements in LGI by selection appear more likely to arise from genetic increases in growth rate than from decreases in weight-corrected fatness, but the inclusion of fatness in the index should lead to the production of lambs that can be taken to heavier weights before becoming overfat.

A preliminary investigation into factors affecting lamb growth on Taranaki hill country - Thomson NA; Brown WB; Mace MJ (Proceedings of the New Zealand Society of Animal Production, 1985)
Lactating or non-lactating Coopworth ewe hoggets were offered low, medium or high herbage allowances for 8 weeks during lactation in each of 2 years. Herbage allowance had only a small effect on the penalty of a hogget lactation. Relative to their non-lactating counterparts, the hoggets that had lactated were on average 12.8 kg lighter at weaning and had a 0.29 kg lower clean fleece weight. These penalties are larger than those reported in other New Zealand studies in which the lactating hoggets were preferentially fed. The lambs reared by the hoggets had live-weight gains typical of those observed in twin lambs reared by adult ewes.

The presence of kallikrein-like enzymes in bovine saliva - McIntosh JT; McLaren RD; Carr DH; Howe GW; Cockrem FRM (Proceedings of the New Zealand Society of Animal Production, 1985)
Normal calvings among 527 cows in a Ruakura Research Station herd (No.1) were not evenly distributed throughout the 24 hours. They were most frequent in the early morning (0100 h to 0600 h, 39%) and afternoon (1300 h to 1900 h, 29%). This diurnal pattern was consistent between years. Altering feeding time from 0700 h to either 1600 h or 1900 h did not increase the frequency of daylight calvings. Feeding at 1900 h did produce 2 periods of intensive grazing each 24 h instead of only one. If a beneficial change in calving pattern is to be produced, it may be necessary to disrupt the period when most cows rest (0100 h to 0600 h) by feeding at around 0300 h.

Replacement policies for dairy cows - McArthur ATG (Proceedings of the New Zealand Society of Animal Production, 1985)
In anoestrous ewes that have been primed with progestagens, the introduction of oestrous ewes together with the teaser rams at progestagen withdrawal increased the percentage of ewes exhibiting oestrus over the subsequent 7 days (19.% teaser rams only v 24.4% teaser rams + oestrous ewes; Experiment 1) and the percentage of ewes ovulating in the subsequent 5 days (7.7% teaser rams only v 21.6% teaser rams + oestrous ewes; Experiment 2). The introduction of oestrous ewes without teaser rams in Experiment 2 failed to stimulate anoestrous ewes to ovulate. When rams were placed with oestrous ewes for 2 days before they alone were introduced to anoestrous ewes, the percentage of ewes ovulating was similar to when rams plus oestrous ewes were present together (38.1% stimulated teaser rams v 35.0% teaser rams + oestrous ewes; Experiment 3). Both of these treatments resulted in more ewes ovulating than in the isolated ewes (0.0%) with the response to unstimulated teaser rams (19.5%) and to oestrous ewes alone (9.5% being intermediate.

Resistance and susceptibility to fleece yellowing and relationships with scoured colour - Wilkinson BR; Aitken FJ (Proceedings of the New Zealand Society of Animal Production, 1985)
Data from 1048 young Angora goats by 15 sires in the Department of Lands and Survey's flock at Waitangi were used to obtain preliminary estimates of the effects of year, age of dam, sex, rearing rank and birth day (age). Characters studied included weaning weight, 6- and 12- month fleece weight, and yearling fleece weight (the sum of 6- and 12- month weights). Estimates were also obtained of the heritabilities of, and the genetic and phenotypic correlations among, these traits. The weaning weights of kids out of dams aged 3, 4, 5 and 6+ years of age were heavier (P<0.001) than those out of 2-year-old dams by 1.9, 2.2, 2.0 and 2.5 kg respectively. Corresponding differences for 6-month fleece weight of kids were 0.05, 0.05, 0.04 and 0.04 kg (P<0.01) but those for 12-month fleece weight were not significant. Males were heavier at weaning than females (1.6 kg, P<0.001) and also had heavier 6-, 12-month and yearling fleece weights (0.08, 0.10 and 0.18 kg respectively; P<0.001). Single-reared animals had significantly heavier weaning weights and 6-month and yearling fleece weights than multiple- reared animals (2.4, 0.09 and 0.11 kg, respectively). Age was a highly significant source of variation for all traits. The heritabilities of weaning weight, and 6-, 12-month and yearling fleece weights were respectively 0.28, 0.23, 0.40 and 0.53. Genetic correlations between weaning weight and 6-, 12-month and yearling fleece weights were respectively 0.0, 0.38 and 0.24. Corresponding phenotypic correlations were 0.58, 0.28 and 0.44.

Response of cows differing in bloat susceptibility to intraruminal water and electrolyte loading - Carruthers VR (Proceedings of the New Zealand Society of Animal Production, 1985)
A simulation model of dairy herds was built to examine the economic consequences of alternative culling policies. Only culling cows on the basis of their first lactation was examined because previous studies had show that it is not worthwhile acquiring more information before making the culling decision. The simulation model shows that the culling decision is sensitive to the ratio of cull salvage value to replacement cost. At a ratio of 0.7, a third of first lactation cows should be culled. Used optimally to make replacement decisions, herd testing is worthwhile particularly if the less expensive alternate month test is used.

A review of the importance of wool traits as genetic improvement objectives and selection criteria for New Zealand Romney sheep - Wickham GA; McPherson AW (Proceedings of the New Zealand Society of Animal Production, 1985)
Genetic parameters of loose wool bulk were estimated by half- sib correlations for Romney ewe and ram hogget fleeces sampled at Tokanui Research Station, Romney and Perendale ewe hogget fleeces sampled at Rotomahana Research Station and Perendale ewe hogget fleeces sampled from 5 industry flocks. Daughter-dam analyses were used to estimate similar parameters for Perendale ewe fleeces sampled at Whatawhata Hill Country Research Station. Heritability estimates for loose wool bulk were 0.34

Skeletal changes and some muscle-skeletal relationships during growth and undernutrition in sheep - Young MJ; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1985)
Eight Friesian bull calves from high breeding index (HBI) parents (mean BI=134) and 8 from low breeding index (LBI) parents (mean BI=104) were allocated to 1 of 2 levels of milk intake from 3 weeks of age until weaning at 7.5 weeks of age. The calves were then grazed at pasture and weighed at 21 to 25 weeks of age. LM calves consumed more herbage organic matter (OM) both before (P<0.01) and for 3 weeks after (P<0.05) weaning. Increasing daily milk intake by 1 litre decreased daily herbage OM intake by 0.11 kg. The total DE intake from 3 weeks to 10.5 weeks of age did not differ significantly between treatments. HM calves grew faster (P<0.05) than LM calves in the pre-weaning period, but no differences were observed from them on. At no stage were significant differences observed in calf live weights between milk treatment groups. There were significant differences in growth rate or herbage intake between BI groups, nor any significant interactions between BI and levels of milk intake.

Suppression of T-cell function in the pregnant ewe - Griffin JFT; Davis GH (Proceedings of the New Zealand Society of Animal Production, 1985)
Increased payment to farmers for leaner lamb carcasses places greater emphasis on specifying target carcass weights and grades on individual farms. In the past there has been little objective information available to help the farmer set these targets and make livestock buying and selling decisions. At the Tomoana freezing works in Hawkes Bay new computer outputs have been introduced to provide the farmer with better information for farm management decision-making. A more detailed lamb grading analysis presenting the number of carcasses within each grade at each carcass weight, and a new output named a "fat trend report" are provided. The fat trend report estimates the relationship between the GR fat depth and carcass weight for each mob of lambs slaughtered. Combined with an iso-dollar overlay, the fat trend report assists in establishing production targets in future mobs for each sheep breed and sex farmed. It is suggested that financial incentives for leaner lamb carcasses should be further increased, to bring carcasses closer to the New Zealand Meat Producers Board's ideal.