@article {3672, title = {Liveweight gain and urinary nitrogen excretion of lambs grazing diverse (plantain, Italian ryegrass and red clover) or ryegrass-white clover pasture in autumn}, journal = {New Zealand Journal of Animal Science and Production}, volume = {80}, year = {2020}, month = {09/2020}, pages = {70-75}, address = {Online}, abstract = {The objective of this study was to investigate the effect of grazing a diverse pasture of plantain, Italian ryegrass, and red clover versus a ryegrass-white clover pasture on the liveweight gain (LWG) and urinary nitrogen (N) excretion of ram lambs over an 82- day experimental period in autumn. Eighty Coopworth ram lambs (8 months old) were allocated to two replicates of two pasture treatments (n = 20), a diverse pasture containing plantain, Italian ryegrass, and red clover (Diverse) and conventional ryegrass-white clover pasture (RGWC). Unfasted live weight (LWT) of lambs was recorded on seven occasions during the autumn experimental period. Apparent dry matter intake (DMI) was estimated as the difference between pre- and post-grazing herbage mass plus daily herbage growth. On two occasions, urine and blood samples were collected from each lamb to determine concentration of urinary N and plasma urea N (PUN). Liveweight gain (P=0.008) and feed conversion efficiency (P=0.022) were greater in Diverse than RGWC treatment (240 vs 160 g/day and 111 vs 86 g LWT per kg DMI, respectively). Urinary N and PUN concentration were similar between treatments; however, when urinary N excretion (g/d) was estimated as a function of PUN, lambs grazing Diverse pasture excreted less (P=0.003) urinary N per 100 g LWG than those grazing RGWC pasture. The proportion of N intake retained in LWG was greater (P=0.008) for lambs grazing Diverse (11.0\%) than those grazing RGWC (9.0\%). The results indicate that there is a potential to achieve target LWT of lambs in a shorter time and with less N loss to the environment by using a diverse mix containing plantain, Italian ryegrass and red clover in comparison to ryegrass-white clover mix in autumn. Keywords: Growing lambs; liveweight gain; urinary nitrogen; diverse pasture; ryegrass}, issn = {1176-5283}, author = {Al-marashdeh O and Cook GA and Anderson FC and Meyer JPH and Logan CM and Edwards GR and Maxwell TMR} } @article {3672, title = {Farm-management tools: reasons for the decision not to use specific tools}, journal = {New Zealand Journal of Animal Science and Production}, volume = {79}, year = {2019}, month = {07/2019}, pages = {125-130}, address = {Palmerston North}, abstract = {There are a large number of management tools available to farmers, however, some are utilised by only a small percentage. The reasons behind the choice not to use a particular tool were investigated using a postal questionnaire that was distributed to all New Zealand sheep farmers in 2014. Farmers were asked first to indicate from a list of 40 farm-management tools those they had used in the previous three years. For tools they had not used, they were asked to select one from a list of eight reasons. A total of 1659 usable questionnaires were received. The most commonly cited reason for not using any given tool was {\textquotedblleft}not relevant to my situation{\textquotedblright} (50.3\%) followed by {\textquotedblleft}benefits not apparent{\textquotedblright} (15.3\%) and {\textquotedblleft}it{\textquoteright}s an unwanted complication{\textquotedblright} (15.0\%). Demographic factors (age, education, gender, farm type and flock size) influenced the reasons for non-use of 20 of the 22 tools. Reasons for non-use of fecundity-boosting vaccine or quarantine treatment for footrot were not influenced (P>0.05) by any demographic factors. The results suggest that although many farmers do not see the relevance of particular tools to their enterprise, demographic factors can influence their reasons for not using a tool. }, issn = {1176-5283}, author = {Corner-Thomas RA and Kenyon PR and Morris ST and Ridler AL and Hickson RE and Greer AW and Logan CM and Blair HT} } @article {3672, title = {Faecal avoidance in Romney sheep lines selected for resistance or resilience to gastro-intestinal nematodes}, journal = {New Zealand Journal of Animal Science and Production}, volume = {78}, year = {2018}, month = {07/2018}, pages = {100-104}, address = {Lincoln}, abstract = {Faecal avoidance was assessed in Romney lambs from lines selected for resistance or resilience to gastro-intestinal nematode parasites. Ten lambs from each selection line that were maintained in separate farmlets and naturally exposed to parasites were assessed on distance grazed from either a mud-clay or faecal ball at 130, 150, 180 and 210 days-of-age. Resistant line animals maintained lower faecal-egg counts compared with resilient lambs, viz. 25.6 c.f. 771.0 eggs per gram of faeces (P<0.001) and greater Trichostrongylus colubriformis-specific immunoglobulin G absorbance (P=0.005) indicating differences between selection lines in parasite loading and immunlogical status. Grazing distance from the object was greatest for faecal ball, viz. 11.53 {\textpm} 1.14 cm compared with mud-clay ball, viz. 4.19 {\textpm} 1.00 cm (P<0.001) and decreased with time (P<0.001). Grazing distance tended to be greater for resilient, viz. 8.63 {\textpm} 1.14 cm than resistant, viz. 7.09 {\textpm} 0.99 cm (P=0.09) but there was no interaction between selection line and ball type (P=0.709) indicating similar levels of faecal-specific aversion between the selection lines. These results suggest that the lesser infection levels in resistant-line animals when grazing is unlikely to be due to reduced exposure to infective larvae as a consequence of greater faecal avoidance.}, issn = {1176-5283}, author = {Hamie JC and Logan CM and McAnulty RW and Greer AW} } @article {3672, title = {Investigation into udder characteristics, mastitis and milk production in crossbred sheep}, journal = {New Zealand Journal of Animal Science and Production}, volume = {78}, year = {2018}, month = {07/2018}, pages = {82-87}, address = {Lincoln}, abstract = {Associations between udder characteristics, milk yield, milk somatic cell counts (SCC) and prevalence of mastitis were evaluated in 121 twin-suckled crossbred non-dairy ewes at four, eight and twelve weeks after parturition. Overall, milk production decreased with time, being 1.09 {\textpm} 0.04 litres per four hours at week four of lactation, 0.68 {\textpm} 0.02 litres at week eight and 0.48 {\textpm} 0.01 litres at week twelve with corresponding mean SCC of 0.32 x 106 cells mL-1, 0.39 x 106 cells mL-1 and 0.28 x 106 cells mL-1, respectively. Incidence of mastitis was 12.7\%, 9.8\% and 8.9\% for weeks 4, 8 and 12, respectively. Of the 20 individuals that displayed SCC indicative of mastitis, only 5 had elevated SCC at more than one sampling time. No consistent association was observed between SCC and visual scores for udder depth, udder distention, degree of separation or teat placement (P>0.05 for all). Milk volume and weight of lamb was greater for ewes with an udder depth of 3 compared with 4 with no other associations evident (P>0.05). Overall, the incidence of subclinical mastitis was low but present in this flock with the udder characteristics assessed here providing poor indicators of either mastitis or milk production.}, issn = {1176-5283}, author = {Yusuf OM and Logan CM and Ridler AL and Greer AW} } @article {3672, title = {Supplementation of ewes on pasture to provide an epidemiological benefit for gastrointestinal parasitism}, journal = {New Zealand Journal of Animal Science and Production}, volume = {78}, year = {2018}, month = {07/2018}, pages = {45-50}, address = {Lincoln}, abstract = {The potential epidemiological benefit of reducing the peri-parturient relaxation in immunity to gastro-intestinal nematode parasites through supplementing twin-bearing ewes during the first four weeks of lactation was evaluated in a replicated farmlet study. In two sequential years, ewes either grazed pasture alone or grazed pasture while supplemented with 0.5 kgDM/d of a high-protein pellet. Supplementation did not affect ewe live weight or body condition score or weight of lamb weaned per ewe (P>0.05). Ewe faecal egg counts (FEC) showed a time x supplementation interaction (P<0.05), being reduced by 50\% from week six of lactation in both years, although this only resulted in transient and inconsistent reductions in pasture larval contamination. After weaning, there was no consistent parasitological benefit to lambs grazing areas where ewes had been supplemented that were reflected in either pasture larvae concentrations, lamb FEC, the requirement for anthelmintic treatment or lamb growth rate (P>0.05 for all). Despite supplementation of ewes during the first four weeks of lactation successfully reducing ewe faecal egg count by 50\%, this was not sufficient to provide a measureable and consistent epidemiological benefit to the lambs.}, issn = {1176-5283}, author = {Tambunan RD and Logan CM and Bywater AC and Greer AW} } @conference {3672, title = {BRIEF COMMUNICATION: The use of farm-management tools by New Zealand sheep farmers: changes with time}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {78-80}, address = {Adelaide}, abstract = {The utilisation of farm-management tools by New Zealand sheep farmers can support on-farm decision making, thus facilitating improvements in productivity and profitability of the farming enterprise. There are numerous management tools available to farmers, for example, a recent report identified 127 tools that were available to New Zealand farmers (Allen \& Wolfert 2011). Although a large number of tools are accessible to farmers, a survey of sheep farmers conducted in 2012 by Corner-Thomas et al. (2015) identified many that were utilised by only a small percentage of farmers. This indicates that there is the potential for increased uptake of management tools which, if relevant, may lead to benefits in on-farm productivity. The aim of the current study was to determine for sheep farmers in New Zealand, if use of farm-management tools had changed over a two-year period.}, issn = {1176-5283}, author = {Corner-Thomas RA and Kenyon PR and Morris ST and Ridler AL and Hickson RE and Greer AW and Logan CM and Blair HT} } @conference {3672, title = {BRIEF COMMUNICATION: Optimizing a fasting protocol to assess live weight of sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {223-224}, address = {Dunedin}, abstract = { }, issn = {1176-5283}, author = {Wilson RF and Hardwick-Smith JA and Logan CM and Corner-Thomas RA and Bywater AC and Greer AW} } @conference {3672, title = {Ryegrass staggers and liveweight gain of ewe lambs and hoggets grazing four combinations of perennial ryegrass and strains of endophyte}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {175-178}, address = {Dunedin}, abstract = { Ryegrass staggers and live weight gain of Coopworth ewe lambs or hoggets were assessed over four eight week trials (two summer, two autumn) for four combinations of perennial ryegrass and strains of endophyte: Arrow with standard (SE, wild type) endophyte, Trojan with NEA3 endophyte, Trojan with a mixture of NEA2 and NEA3 endophytes, and Rohan with a mixture of NEA2 and NEA6 endophytes. In each trial, three replicates of 10 to 12 sheep were assigned to 0.3 ha plots of each cultivar x endophyte strain combination, with herbage mass reduced from 3-4000 kg DM/ha to 1500 kg DM during the eight weeks. Severe ryegrass staggers occurred in all four trials in Arrow SE, with a mean ryegrass staggers score ranging between 1.65 to 2.8 (0 to 5 scale). Minor ryegrass staggers occurred in Trojan NEA3, Trojan NEA2/3, Rohan NEA2/6 in two of the four trials, but only with a low mean score (<0.4). Live weight gain was lower in Arrow SE than the other cultivars in three of the four trials. Trojan NEA3 had live weight gain that was different from Trojan NEA2/3 (+27 g/head/day higher in Trojan NEA2/3) on one trial only. The perennial ryegrass cultivar x novel endophyte strain combinations Trojan NEA3, Trojan NEA2/3 and Rohan NEA2/6 showed liveweight gain that was similar or greater than the standard endophyte control, and caused minimal ryegrass staggers in {\textquoteleft}worstcase scenario{\textquoteright} conditions designed to induce this.}, issn = {1176-5283}, author = {Logan CM and Edwards GR and Kerr GA and Williams S} } @conference {3678, title = {BRIEF COMMUNICATION: Ewe ultra-sound pregnancy diagnosis and its use by New Zealand farmers}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {74}, year = {2014}, month = {06/2014}, pages = {65-67}, address = {Napier}, abstract = {Ultra-sound pregnancy diagnosis can be a valuable management tool for sheep farmers. The benefits include early identification of non-pregnant (dry) ewes which can be culled, freeing up valuable feed for pregnant ewes (Blair 1986) and the identification of single, twin and triplet fetuses, allowing ewes to be fed based on their specific nutritional requirements during pregnancy (Garrick 1998). In addition, selection of lambing paddocks can be made based on the number of fetuses identified (Garrick 1998).}, issn = {1176-5283}, author = {Corner-Thomas RA and Kenyon PR and Morris ST and Ridler AL and Hickson RE and Greer AW and Logan CM and Blair HT} } @conference {3678, title = {BRIEF COMMUNICATION: Performance of lambs exposed to a desensitising regime prior to infection with Trichostrongylus colubriformis}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {74}, year = {2014}, month = {06/2014}, pages = {73-75}, address = {Napier}, abstract = {Enhancing the immune response of lambs against the gastrointestinal nematode Trichostrongylus colubriformis through vaccination has been previously investigated (Windon et al. 1984; Douch 1989; McClure 2009). However, the majority of production loss from this parasite species in sheep has been attributed to components of the immune response (Greer et al. 2005). As such, manipulation of the host immune response through desensitisation may provide a novel method of reducing production loss associated with infection. The objective of this investigation was to evaluate the ability of a desensitising regime with parasite antigens to reduce the production cost associated with Trichostrongylus colubriformis infection in lambs...}, issn = {1176-5283}, author = {Greer AW and Huntley JF and Hogan A and Logan CM and McAnulty RW and McNeilly TN} } @conference {3678, title = {Predicting fleece weight from the difference in live weight pre- and post-shearing}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {74}, year = {2014}, month = {06/2014}, pages = {68-72}, address = {Napier}, abstract = {Radio frequency identification (RFID) and automated weighing platforms facilitate the practicality and ease with which individual live weight (LW) can be recorded. This raises the possibility for the difference in recorded LW of sheep between pre- and post-shearing to provide an estimate of fleece weight (eFW) which, in turn, could allow selection pressure to be applied for improved wool production. The eFW of yearling ewes (n=98), yearling rams (n=274) and mixed-age ewes (n=305) were compared with their recorded fleece weight (FW). Positive linear correlations (P<0.001 for all stock classes) were observed between eFW and FW and also the eFW rank and FW rank. Although some variability between stock classes existed, for all data combined, FW rank was able to account for 42\% of the variation in eFW rank. Further, selecting individuals on eFW was able to retain an average of 64\% of the selection differential obtained using recorded FW. Overall, these results suggest eFW calculated from the difference in LW between pre- and post-shearing, in combination with RFID and automated weighing platforms, may provide a useful and practical tool to assist with selection for improved wool production in a commercial setting.}, issn = {1176-5283}, author = {Galway JM and Logan CM and Bywater AC and Greer AW} } @conference {89241, title = {Can weighing multiple times increase the accuracy of live weight recording?}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {73}, year = {2013}, month = {Jan}, pages = {146-148}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {

The recording of live weight in livestock enterprises is fundamental for breeding and production, the ease of which has been greatly improved with the advent of automated weighing and recording platforms. However, the extent to which significant advances within a livestock enterprise can be made with the utilization of live weight data depends on the validity of the indicated weights which can be influenced by measurement error from a number of sources (Hughes 1976). Thus, the use of scales only provides an estimate of an animal{\textquoteright}s true live weight. Despite the importance of live weight, there is a distinct paucity of published data surrounding the variation in live weight estimates and weighing protocols that may be used to reduce this variation.

}, issn = {1176-5283}, author = {Galwey JM and Logan CM and Greer AW} } @conference {89248, title = {Evaluation of lambs subjected to a targeted selective treatment anthelmintic regime}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {73}, year = {2013}, month = {Jan}, pages = {175-179}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {

Targeted selective anthelmintic treatments (TSTs) can identify individuals less reliant on anthelmintic, information from which could be utilised to select lambs based on anthelmintic requirement. However, it is important to first determine if selection based on anthelmintic requirement compromises genetic potential for productive traits. Sheep Improvement Limited (SIL) estimated breeding values (eBVs) for production traits and associated indexes for 214 female lambs and 158 male Coopworth lambs were compared with their requirement for anthelmintic following exposure to a liveweight gain-based TST regime. Mean liveweight gain for both sexes was reduced with increasing anthelmintic requirement (P \<0.001). Favourable increases in eBVs with decreasing anthelmintic requirement wereobserved for fecundity in both sexes (P = 0.003) and for survival in females only (P = 0.03). No effect was observed for eBVs for maternal survival, weaning weight, maternal weaning weight, live weight at eight months of age, and live weight and fleece weight at 12-months of age (P \>0.05 for all). Dual purpose index values for resilience increased with decreasing anthelmintic requirement (P \<0.001) while meat yield index and overall productivity were not affected (P \>0.05 for both). It is concluded that selection of lambs for low anthelmintic requirement can be made with no apparent compromise in the genetic potential for production traits.

}, issn = {1176-5283}, author = {Greer AW and Pettigrew CA and Logan CM} } @conference {75882, title = {Flexibility and climate risk management in high stocking rate dryland sheep farming systems}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {96-102}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {A trial unit of 87.8 ha with conventional grass-based pastures and one of 85.1 ha with high legume-content pastures were used to investigate the impact of climate-risk management strategies on production and profitability of dryland sheep farming systems. The target stocking rate of both units was 14 stock units (SU)/ha, which is markedly higher than the regional monitor farm at 8.8 SU/ha. Information on the feed supply and animal feed requirement of the two units for 2008/09 and 2009/10 are presented, along with differences in weather patterns, soils moisture, climate-risk responses used, and stock sales between the two years. Results from the grass-based unit indicated that the flexible livestock policies used and climate-risk management responses imposed were able to increase farm profitability and reduce its variability between years in comparison to the local Ministry of Agriculture and Forestry monitor farm model. However, the same was not true for the high legume-content unit, which encountered a number of problems with high lamb deaths and poor lamb finishing in 2008/09. Soil moisture level in the top 25 cm proved to be a simple, inexpensive and effective indicator for making appropriate farm management decisions in response to changes in the climate.}, issn = {1176-5283}, author = {Bywater AC and Logan CM and Edwards GR} } @conference {75883, title = {Pasture growth and quality, and lamb growth rates in high stocking rate dryland sheep farming systems}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {103-108}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {Pasture growth and quality, and lamb growth rates were measured on a conventional grass based trial unit of 87.8 ha and a high legume unit of 85.1 ha, established to investigate climate-risk management strategies within high stocking rate dryland sheep farming systems. There was no difference between the units in total pasture production with a pasture utilization of 71.7\% and 74.3\% on the grass and legume units, respectively. Metabolisable energy values remained close to, or above, the target values throughout the growing season. Preweaning lamb growth rates averaged 304 g/day on both units. There were significant differences between singles (342 g/day), twins (300 g/day) and triplets (254 g/day) and between lambs from first cycle (294 g/day) and main mob ewes (315 g/day). There were some differences in lamb growth rates between different pastures types but these were not consistent between years. Post-weaning growth rates averaged 137 g/day with significant differences attributable to litter size, mob and year. Growth from birth to sale averaged 295 g/day, slightly less than the target of 300 g/day. Thus high lamb growth rates are possible on a range of pasture types on dryland at low pasture covers of high quality.}, issn = {1176-5283}, author = {Bywater AC and Logan CM and Edwards GR and Sedcole JR} } @conference {69507, title = {Suitability of the Happy Factor decision support model as part of targeted selective anthelmintic treatment in Coopworth sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {213-216}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {The suitability of the Happy Factor decision support model as the determinant of a targeted selective treatment regime incorporated into an automated weighing and drafting facility was evaluated in a Canterbury environment. One hundred and twenty, six-month-old Coopworth lambs naturally infected with gastrointestinal parasites were weighed and faecal sampled every two weeks for eight weeks. Individual performance targets during each two week period were calculated using the Happy Factor decision support model. Lambs that did not reach their performance target were automatically drafted out and subsequently treated with anthelmintic. Those deemed to benefit from treatment had significantly greater faecal egg count (FEC) than their untreated counterparts at Week 4 only, were lighter on Weeks 2 and 8, but had lower liveweight gains on all four occasions. Overall, the system provided a rapid and reliable method of identifying and separating poorer performing individuals, which were not necessarily those with a high FEC or those that were lighter. Furthermore, the optimum treatment threshold was determined to be 0.74, which is greater than previously published values of 0.66 for Scottish Blackface sheep. This suggests that validation of an optimum Happy Factor treatment threshold for each environment and/or animal genotype may be required.}, issn = {1176-5283}, author = {Greer AW and McAnulty RW and Logan CM and Hoskin SO} } @conference {60978, title = {Genetic and phenotypic parameter estimates for growth, yield and meat quality traits in lamb}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {69}, year = {2009}, month = {Jun}, pages = {210-214}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {The Meat and Wool New Zealand Central Progeny Test has evaluated 143 sires from terminal and dual purpose breeds for meat yield and growth. Meat quality traits, including pH, fat and meat colour (CIE L*, CIE a*, CIE b*) have also been measured. This paper determines genetic variation in these quality traits and their correlations with growth and meat yield. Progeny were drafted for slaughter at a threshold live weight of 34 kg at weaning and 36 kg for subsequent slaughters. Fat colour, eye muscle meat colour and meat pH were measured 24 hours post-slaughter, with meat colour measured after a 30 minute bloom. Heritabilities and genetic correlations between traits were calculated from the measurements. Data were analysed with a linear mixed model in ASReml. Results showed significant variation among sires for meat quality. Heritabilities were moderate for most meat quality traits: fat colour (CIE b* 0.42), initial meat colour (CIE L* 0.29, CIE a* 0.19) and pH (0.12). Relationships between meat quality and yield/growth showed that meat CIE L* had a positive genetic correlation with weaning weight (0.42). Simulated index selection for growth rate and meat yield predicted a small increase in meat lightness and decline in fat yellowness (0.231 and -0.227 units per generation and unit selection intensity, respectively). }, issn = {1176-5283}, author = {Payne GM and Campbell AW and Jopson NB and McEwan JC and Logan CM and Muir PD} } @conference {60979, title = {Genetic parameters for primal cut meat yield traits in sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {69}, year = {2009}, month = {Jun}, pages = {215-219}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Lamb carcass grading is changing from classification on carcass weight and tissue depth (GR) to yield grading systems such as VIAscan{\textregistered}. Under the VIAscan{\textregistered} system, farmers receive information on the percentage lean meat yield from the hindleg, loin and shoulder primal cuts, and payments are based on these measurements. Genetic improvement programmes for meat have concentrated on producing age-adjusted breeding values for carcass lean and fat weight from live weight and ultrasonic eye muscle measurements. This has worked well for grading using carcass weight and GR, but does not quantify differences in yield between meat cuts. Carcass and VIAscan{\textregistered} yield data collected for the Meat and Wool New Zealand Central Progeny Test were analysed to determine heritabilities and genetic and phenotypic correlations for meat yield traits. The dataset contained around 6,600 progeny from 143 terminal sire or dual purpose rams. Data were analysed using linear mixed models in ASReml. The results showed significant variation between sires for lean yield traits. Heritabilities for age-adjusted lean weight in the hindleg, loin and shoulder were 0.40, 0.37 and 0.42, respectively. Genetic correlations for age-adjusted weight of lean by carcass region were all high (range 0.94 to 0.96), but were lower (0.62 to 0.85) when adjusted to constant carcass weight. }, issn = {1176-5283}, author = {Jopson NB and McEwan JC and Logan CM and Muir PD} } @conference {42048, title = {Artificial insemination success rates for Meat and Wool New Zealand central progeny test sires}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {68}, year = {2008}, month = {Jan}, pages = {77-78}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Brisbane, Australia}, abstract = {National progeny testing schemes have become important components of national sheep genetic improvement programmes in Australia, France, and New Zealand (Fogarty et al., 2002; Bib{\'e} et al., 2002; Campbell et al., 2005). In 2001 the Alliance Central Progeny Test was established, this was combined in 2005 with the Elite Lamb Progeny Test to become the Meat and Wool New Zealand Central Progeny Test (CPT). Over the past six seasons, a total of 120 leading industry sires, comprising 14 different breeds, have been mated via artificial insemination. CPT rams are genetically connected via common sires ...Continued }, issn = {1176-5283}, author = {McLean NJ and Dodds KG and Knowler KJ and Jopson NB and Behrent M and Logan CM and Muir PD and Shackell GH and McEwan JC} } @conference {41676, title = {An evaluation of sheep meat genetics in New Zealand: The central progeny test (CPT)}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {66}, year = {2006}, month = {Jan}, pages = {368-372}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Napier}, abstract = {The New Zealand Central Progeny Test (CPT) was first established in 2001 with the aims of improving the carcass dollar value of sires and establishing genetic links among sire referencing schemes. Over the past three seasons, a total of 72 sires from both terminal and dual purpose breeds have been evaluated for meat genetics at the AgResearch Woodlands farm and the Lincoln University Ashley Dene farm. All progeny, except the 2004 born ewe progeny from the dual purpose sires, were slaughtered at monthly intervals from December to March each year through two Alliance plants, at threshold liveweights of 34kg. Carcass measurements included cut yield (measured by ViaScan grading) eye muscle area, GR, meat pH, meat and fat colour and days to reach an 18kg carcass weight. These measurements were used to calculate three key indices; days to kill, meat value and a combined meat and growth index, as well as individual breeding values. Results showed significant variation among sires for all key traits and that no single ram or breed dominated the top of the indices or breeding values. The range of economic value was approximately $10 across the terminal and dual purpose sires evaluated, demonstrating that considerable potential exists to identify and select better terminal sires. The CPT is now commencing maternal evaluation, using the retained ewe lambs produced from the dual purpose sires. }, issn = {1176-5283}, author = {McLean NJ and Jopson NB and Campbell AW and Knowler K and Behrent M and Cruickshank G and Logan CM and Muir PD and Wilson T and McEwan JC} } @conference {41424, title = {Recognising the limits to live weight-reproduction relationships in ewes}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {63}, year = {2003}, month = {Jan}, pages = {140-143}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Queenstown}, abstract = {The relationship between joining live weight and ovulation rate and number of lambs born was examined in a composite flock of small- and large-framed ewes. Approximately equal numbers of small- (n = 315) and large (n = 305) framed, mixed-age ewes of equal average condition score, selected in the same proportion from 9 commercial flocks (mainly Coopworth), were managed together from early March to pre-lambing. The average pre-joining live weight ({\textpm}SD) of small-framed ewes (61.3 {\textpm}6.35 kg). was significantly (P<0.001) lower than that of large-framed ewes (71.1{\textpm}6.58 kg). Ewes were joined with 14 Coopworth ram hoggets fitted with ram harnesses on 8 April. Ewes marked by rams were temporarily removed from the flock every 7 days for 21 days and ovulation rate (0, 1, 3, 4) recorded by laparoscopy the following day after fasting. Pregnancy status (0, 1, 2 or more) was recorded by ultrasonography on 4 July. Ewes were fully recorded at lambing. The mean ovulation rate (OR) of small-framed ewes was significantly lower (1.76, P<0.05) than that of large-framed ewes (1.92). The regression of OR on joining live weight (jLW) was significant (P<0.001) for small-ewes (OR = 0.0216 x jLW + 0.463) but there was no relationship between OR and jLW in large-framed ewes. Maximum OR (1.92) was predicted to occur at 67.5 kg jLW. The results of this study indicate an upper limit to the live weight ovulation rate relationship. Compared on the basis of equal ewe live weight per ha, OR per ha was 12\% higher for small- than large-framed ewes. }, issn = {1176-5283}, author = {Rutherford L and Nicol AM and Logan CM} } @conference {40816, title = {Prediction of carcass tissue weight in vivo using live weight, ultrasound or X-ray CT measurements}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {56}, year = {1996}, month = {Jan}, pages = {205-211}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Twenty-one Dorset Down ewe hoggets (49.4kg body weight, 9months old) were scanned by ultrasound and X-ray computer tomography (CT). Total carcass tissue (fat, muscle and bone) weights were assessed by the Cavalieri procedure from 16-18 CT slices per animal. Additional CT slices were taken at four anatomical reference sites; 7th thoracic (TV7), 2nd lumbar and 5th lumbar vertebrae (LV5), and mid-shaft of the femur. Subcutaneous fat depth and muscle depth were assessed over the last rib using ultrasound. Body weight, ultrasound measurements and reference slice carcass tissue areas were used to predict total carcass tissue weights by multiple regression techniques. In combination with BW, single CT slices predicted tissue weight more accurately than ultrasound measurements with BW for fat (R2=72-84\% vs. 63\%) but not for muscle (R2=79-87\% vs. 83\%) or bone (R2=62-66\% vs. 65\%). The best combination of two CT slices was TV7 \& LV5. In combination with BW these improved prediction accuracy further (fat, R2=92\%, muscle, R2=91\%, bone, R2=71\%). It is possible that data from a single CT slice predict carcass tissue weight less accurately than expected due to anatomical registration errors despite CT producing better quality images than ultrasound. These errors are attributed to scanning protocol constraints for CT equipment. Two or more CT slices need to be scanned in order to predict tissue weight more accurately than ultrasound.}, issn = {1176-5283}, author = {Young MJ and Nsoso SJ and Logan CM and Beatson PR} } @conference {40612, title = {Responses to selection for lean tissue growth in Dorset Down sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {54}, year = {1994}, month = {Jan}, pages = {255-260}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Responses to selection using a lean tissue growth index were estimated from performance data of the Lincoln University Dorset Down flock. Data were available for ewes (n=922) born in the years 1984 - 1991 and rams (n=816) born in 1984 - 1992. Data were from two closed lines, one control and the other selected for high lean tissue growth. Initially selection was on the basis of an index comprising measurements of live weight and fat depth. Subsequently muscle depth was incorporated into the index. Ewes and rams born in spring each year were run separately at pasture from weaning (late summer) onwards. Performance testing was in the following autumn for ewes and winter for rams. Measurements were live weight and in vivo ultrasonic fat and muscle depths. Responses were calculated from regression of the difference between the line means for breeding value against time. Breeding value estimates were derived by AIREML analyses. Both sexes exhibited desirable responses in all component traits: rams; +0.290kg/yr, +0.019mm/yr and -0.013mm/yr and ewes; +0.154kg/yr, +0.028mm/yr and -0.028mm/yr for live weight, muscle and fat depths respectively. Increases in muscle depth occurred after it was incorporated into the selection index. }, issn = {1176-5283}, author = {Nsoso SJ and Beatson PR and Young MJ and Logan CM} } @conference {40371, title = {Factors affecting repeatability of tissue depth determination by real-time ultrasound in sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {52}, year = {1992}, month = {Jan}, pages = {37-40}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The behaviour of 7476 calves transported on double- or triple- decker trucks was studied during unloading. Recorded behaviour was classified into 2 categories (upright or not upright) and the frequencies of these at three ramp slopes (4.2, 12 and 18.8 ) are presented. The proportions of animals upright on the 3 slopes (low, medium and high) were 93, 74 and 20\%. On average, 100 calves were unloaded in 5.3, 7.7 and 7.1 min down the low, medium and high slopes, respectively. Improvements in welfare of bobby calves and probably reduced bruising would result if ramp slopes were kept at less than about 12 so that most animals could remain upright. }, issn = {1176-5283}, author = {Young MJ and Deaker JM and Logan CM} }