@article {3672, title = {Genome-wide association studies for milk traits in New Zealand dairy sheep}, journal = {New Zealand Journal of Animal Science and Production}, volume = {82}, year = {2022}, month = {01/2022}, pages = {64-68}, address = {Online}, abstract = {The New Zealand dairy sheep industry has grown markedly in the last decades. With better genetics and management, companies have been able to improve key production traits. This study aimed to identify single nucleotide polymorphisms (SNPs) associated with milk traits in dairy sheep. We performed genome-wide association (GWA) analyses for milk yield, fat and protein content using data from commercial farms. We used 54,698 milk yield records and 24,891 fat and protein records from 4,590 and 2,823 ewes, respectively. Phenotypes were collected between August 2018 and April 2021 across three locations in New Zealand. They were adjusted for flock, age, lactation, lambing date, weeks in milk and permanent environment. Animals were genotyped with commercial SNP chips with 13,759 markers available after quality control. GWA models included the genomic relationship matrix, three principal components and genomic inflation correction for the p-values. We found four genome-wide significant associations for milk yield. These variants were mapped to eight genes, PDZRN4 (intron), EDEM2, PROCR, MMP24 (intron), EIF6, FAM83C, UQCC1, and HDAC9 (intron). Of these, PDZRN4, HDAC9 and MMP24 were associated with milk traits in previous studies. No significant associations were found for fat and protein content. Genes shown here are promising candidate genes, requiring validation in independent samples.}, issn = {1176-5283}, author = {Costilla R and Chan PB and Mcrae KM and McEwan JC and Dodds KG and Newman SA and Baird HJ and Henry H} } @article {3672, title = {Sheep divergently selected for methane yield showed differences in meat fatty acid composition}, journal = {New Zealand Journal of Animal Science and Production}, volume = {81}, year = {2021}, month = {01/2022}, pages = {173-178}, address = {Online}, abstract = {The purpose of this work was to investigate whether 18-month-old rams from the methane selection lines differed in their levels of soft tissue depth over the 12th rib (GR, as a proxy of carcass fatness) intramuscular fat (IMF), and the fatty acid composition of IMF. The rumen is the site of microbial biohydrogenation of consumed plant fatty acids and synthesis of unique microbial body fatty acids. It is known that there are differences in the microbiome and fermentation characteristics of sheep selected for and against methane production (methane selection lines). When comparing the high and low lines several differences were found. Rams from low-methane-yield-selection lines tended to have lower GR (P<0.06) than those from high line rams, but there was no evidence for a difference in levels of IMF between the lines (P=0.77). There were, however, many significant differences in the fatty acid composition (as a \% of total fatty acids) of the IMF between the lines. The IMF from the low-methane-yield line had a significantly (P<0.05) higher proportion of branched-chain fatty acids, and fatty acids that are associated with the early stages of the biohydrogenation pathways in the rumen, specifically conjugated linoleic acid (CLA) and C18:1 t11 but with less C18:0 stearic acid (the end product of biohydrogenation) and a significantly higher proportion of C16:1 t9 which is produced through β-oxidation of C18:1 t11. These results provide insight into how differences in sheep from the methane-yield selection line may influence the fatty acid composition of their fat. Keywords: Methane; sheep; intramuscular fat; fatty acid composition}, issn = {1176-5283}, author = {PL Johnson and Agnew M and Jonker A and Hickey SM and McEwan JC and Bryson B and Dodds KG and Rowe SJ} } @article {3672, title = {BRIEF COMMUNICATION: Potential alterations in New Zealand sheep, beef cattle and deer numbers due to climate change: what can genetics offer?}, journal = {New Zealand Journal of Animal Science and Production}, volume = {78}, year = {2018}, month = {07/2018}, pages = {146-150}, address = {Lincoln}, abstract = {Many producers of red meat in New Zealand run enterprises consisting of a mix of sheep, beef cattle and deer, with obvious differences in species ratios across regions when aggregated. The aim of this study was to use these regional species ratios to predict livestock number changes in New Zealand in response to climate change. Simple linear regression was performed using mean temperature and species ratio (sheep, beef cattle and deer) for each region. The slopes of these linear equations were used to estimate {\textquotedblleft}business-as-usual{\textquotedblright} for each region in year 2100 under different models of climate change. An overall decrease in sheep and deer numbers by up to 38\% and 75\%, respectively, is predicted, along with an increase in beef cattle numbers by up to 60\%. Genetics provides an opportunity to select for animals that are adapted to the changing environment through reproductive plasticity, disease resistance, and heat tolerance, and therefore to moderate these predicted changes.}, issn = {1176-5283}, author = {Mcrae KM and Rowe S and McEwan JC} } @conference {3672, title = {BRIEF COMMUNICATION: Preliminary estimates of genetic parameters for adult dag scores in New Zealand sheep and their relationship with juvenile measurements}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {144-145}, address = {Adelaide}, abstract = {The accumulation of faecal material around the breech area of sheep (dags) is of interest to the New Zealand sheep industry for a variety of reasons, including financial penalties for presenting animals with dags at slaughter, reduced wool value, increased risk of flystrike and the labour cost associated with dagging both lambs and adult ewes (Pickering et al. 2012). Currently, dag scores at both three (DAG3) and eight (DAG8) months of age are routinely measured, and analysed in Sheep Improvement Limited (SIL). However, there are currently no formally published estimates of the genetic relationship between dag score as a lamb and dag score as an adult (DAGA) in the New Zealand sheep population. Adult dag score has been found to be highly repeatable between 12 months to two years of age (R = 0.42) and between two and three years of age (R = 0.44) in different strains of Merino sheep (Larsen et al. 1995). Currently within SIL, the estimated breeding values (EBVs) calculated from DAG8 measures are reported as the adult dag score EBVs. There are now, however, multiple flocks recording adult dag score in the SIL database. An analysis of the correlation of adult dag score with DAG8 and DAG3 would confirm if the current SIL model is appropriate for reporting adult dag EBVs, or if the model needs revising to include adult dag measures and its correlations with DAG3 and DAG8.}, issn = {1176-5283}, author = {Mcrae KM and Dodds KG and Newman S-AN and Brito LF and Pickering NK and McEwan JC} } @conference {3672, title = {2015 NZSAP Living Legend Address {\textendash} Invermay Agricultural Centre}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {149}, address = {Dunedin}, abstract = {Some of the best science is done by those who are excited by their research and by working with industry. Many breakthroughs come from people noticing, and following up on, unusual observations or anomalies. Often, their passions are funded {\textquotedblleft}from the back pocket{\textquotedblright} for several years; until sufficient information is secured to justify a formal funding application. The Living Legend Lecture invites distinguished longterm members of NZSAP to make a scholarly presentation at the Society{\textquoteright}s annual conference in recognition of their contribution to New Zealand Animal Production over a substantial period of time. Heeding the Guidelines recommendation to consider members resident in the area holding the conference, the 2015 organising committee chose to nominate the contributions of the scientists and technical staff of an iconic Institution, rather than acknowledge a single individual{\textquoteright}s work. No specific animal production {\textquotedblleft}theme{\textquotedblright} was selected. Instead, it was decided to highlight the contribution of the Invermay Agricultural Centre as a whole...}, issn = {1176-5283}, author = {Shackell GH and Drew KR and Fennessy PF and Allison AJ and McEwan JC and Crawford AM} } @conference {3672, title = {BRIEF COMMUNICATION: Developing genomic tools in the New Zealand Deer Industry}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {91-93}, address = {Dunedin}, abstract = { }, issn = {1176-5283}, author = {Rowe SJ and Clarke SM and Van Stijn TC and Hyndman DL and Ward JF and McEwan KM and Dodds KG and McEwan JC and Newman S-AN and Asher GW} } @conference {3672, title = {BRIEF COMMUNICATION: Genetic control of the rumen microbiome in sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {67-69}, address = {Dunedin}, abstract = { }, issn = {1176-5283}, author = {Rowe SJ and Kittelmann S and Pinares-Pati{\~n}o CS and Wood GR and Dodds KG and Kirk MR and Ganesh S and Hickey SM and Janssen PH and McEwan JC} } @conference {3672, title = {BRIEF COMMUNICATION: Genetic parameters for growth, carcass and meat quality traits in New Zealand sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {94-96}, address = {Dunedin}, abstract = { }, issn = {1176-5283}, author = {Brito LF and Miller SP and Clarke SM and Dodds KG and Bain WE and Lee MA and Pickering NK and McEwan JC} } @conference {3678, title = {BRIEF COMMUNICATION: An exploratory investigation of the effects of selection for divergence in methane emissions on rumen digesta and carcass traits in 8-month old sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {74}, year = {2014}, month = {06/2014}, pages = {142-144}, address = {Napier}, abstract = {Global agriculture accounts for approximately 14\% of anthropogenic emissions. In New Zealand, methane emissions from ruminants comprise 31.5\% of the total emissions (Ministry for Environment 2009), therefore, any future mitigation of emissions could have substantial economic implications for the agricultural sector. Reducing emissions from ruminant livestock without affecting animal production against a rising demand for animal products is challenging (Clark 2009). Measurements carried out over the last 15 years have shown a common feature of individual animal variation in methane emissions (Pinares-Pati{\~n}o et al. 2011b). Recently it has been shown that enteric methane emissions from sheep are both heritable and repeatable (gCH4/day 0.29 {\textpm} 0.05; repeatability 0.26 {\textpm} 0.02), whether expressed as gross emissions (g/d) or methane yield (emissions per unit of feed dry matter intake, g/kgDMI; Pinares-Pati{\~n}o et al. 2013). This makes breeding an attractive mitigation strategy for the lowering of enteric emissions from ruminant livestock given animal production performance is not affected (Pinares-Pati{\~n}o et al. 2011a)...}, issn = {1176-5283}, author = {Elmes SN and Bain WE and Greer GJ and Hickey SM and Young EA and Pickering NK and Rowe SJ and Knowler KJ and Pinares-Pati{\~n}o CS and McEwan JC} } @conference {89264, title = {Genome wide DNA methylation patterns and transcription analysis in sheep muscle}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {73}, year = {2013}, month = {Jan}, pages = {37-40}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {

The Carwell phenotype is a desirable inherited muscular hypertrophy of the Longissimus dorsimuscle in Poll Dorset sheep that does not have any detrimental effect on eating quality, fat deposition or detectable meat tenderness. The Carwell haplotype has been localized to a 350kb region on the distal end of OAR18 near the Callipyge locus (Nicoll et al. 1998) containing three known genes. However, in spite of considerable effort in sequencing and resequencing, the causative mutation has not been identified. Although unsuccessful in identifying the causative mutation, these studies have revealed that the Carwell phenotype displays an imprinted inheritance pattern, with increased muscling associated with inheritance from the sire but not the dam.

}, issn = {1176-5283}, author = {Couldrey C and Brauning R and MacLean PH and Henderson HV and McEwan JC} } @conference {79010, title = {Development of epigenomic analysis in agricultural animals}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {163-165}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Advances made in DNA sequencing technologies over the past 15 years (Zhao \& Grant 2011) have resulted in genome wide selection for production traits becoming a reality. Soon all sequence variations in each individual in closed breeding schemes will be known. What is not currently known is how to rank these variations, especially those that involve changes in gene expression rather than amino acid sequence. In order to continue making genetic progress we will need an understanding of how epigenetics affects gene expression and ultimately phenotype.}, issn = {1176-5283}, author = {Couldrey C and Brauning R and Retzel EF and McEwan JC} } @conference {79017, title = {Estimates of genetic parameters for flystrike in New Zealand Romney and Romney cross sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {189-191}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {

Myiasis, or flystrike, is a major animal welfare problem for sheep that causes significant production losses and potentially death. It is estimated that the prevalence of flystrike is 3-5\% in the national flock (Heath \& Bishop 1995) and is estimated to cost the New Zealand industry $40 to $50 million annually (Beef + Lamb New Zealand 1999). These costs accrue via production losses through reduced wool and body growth, morbidity, and control strategy costs including insecticide, lamb shearing and crutching. ... continued

}, issn = {1176-5283}, author = {Pickering NK and Dodds KG and Blair HT and Hickson RE and PL Johnson and McEwan JC} } @conference {79007, title = {Genetic and phenotypic parameters for stayability in a New Zealand research flock}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {152-155}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Productive lifespan is important to commercial farmers, as ewes that are culled prematurely from the flock represent a considerable cost. The greater the number of replacements retained, the fewer the number of animals available for sale, and the greater proportion of the farm that must be allocated to rearing replacements at the expense of carrying more productive ewes. As selection occurs in stud flocks, Sheep Improvement Ltd. (SIL) developed an exit fate recording system that distinguishes between commercial culls of unsound sheep and the culling of sound sheep based on knowledge such as pedigree or genetic merit that would not usually be available to commercial breeders. Ewes culled for commercial ... continued}, issn = {1176-5283}, author = {McIntyre SB and Newman SAN and Young EA and McEwan JC} } @conference {75915, title = {BRIEF COMMUNICATION: Arapawa: a novel New Zealand sheep breed of distinct origin}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {248-250}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {Arapawa sheep are a feral breed found on Arapawa Island in the Marlborough Sounds, New Zealand. Their origin is not documented, but it is thought to be one of the oldest feral flocks in New Zealand dating back to approximately mid 1800s (Orwin et al., 1984). There are numerous... Continued}, issn = {1176-5283}, author = {Young EA and Kijas JW and Mcculloch R and Scobie DR and Mcrae KM and Pickering NK and Dodds KG and McEwan JC} } @conference {75918, title = {BRIEF COMMUNICATION: Genomic selection in the New Zealand Sheep industry using the Ovine SNP50 Beadchip}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {263-265}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {The Illumina OvineSNP50 BeadChip is a single nucleotide polymorphism (SNP) microarray targeting 54,241 evenly spaced SNPs on the sheep genome, developed by Illumina in collaboration with AgResearch, Baylor, UCSC, CSIRO, and the USDA as part of the International Sheep Genomics Consortium. It was used to genotype key... Continued}, issn = {1176-5283}, author = {Auvray B and Dodds KG and McEwan JC} } @conference {75909, title = {Is rumen retention time implicated in sheep differences in methane emission?}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {219-222}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {Breeding ruminants for low methane (CH4) emissions is an attractive mitigation approach for this greenhouse gas. During the last three years research has progressed at AgResearch to accurately identify individual sheep with contrasting low (Low) and high (High) methane yields. A study was conducted using these animal resources in order to explore the animal factors responsible for the observed differences between rankings. For this, the sheep were fed first on fresh pasture forage (pasture) and then on pellets containing lucerne hay and wheat grain (pellet). Methane emissions were measured in respiration chambers over two consecutive days. Feed dry matter digestibility (DMD) was estimated from a total faecal collection, whereas ruminal retention times of feed particles (PRRT) and solutes (SRRT) were estimated by single dosing of external markers. Methane yields from the High sheep were higher (P >0.05) than from their Low counterparts both the pasture and pellet diets. High emission ranking sheep had higher (P <0.05) DMD and SRRT than their Low counterparts, whereas PRRT was only numerically higher for the High sheep than for the Low sheep. Results of this study align with previous findings that retention time of digesta is implicated in animal differences in CH4 emission.}, issn = {1176-5283}, author = {Pinares-Pati{\~n}o CS and Ebrahimi SH and McEwan JC and Dodds KG and Clark H and Luo D} } @conference {69487, title = {Carcass linear measurements as predictors of meat yield in lambs determined by VIAscan}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {130-132}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {Lambs yielding proportionally more lean meat are desirable to processing companies as they have a greater quantity of saleable product which also meets market demand withoutthe need for further processing. The quest for higher yielding lean lambs has seen a change in the lamb carcass grading system from classification on carcass weight and the GR measurement (total tissue depth above the 12th rib, 110 mm from the midline) (Kirton, 1989) to using imaging systems such as VIAscan{\textregistered}. VIAscan{\textregistered} is a two dimensional imaging system that estimates lean content of the carcass (Hopkins et al., 2004).}, issn = {1176-5283}, author = {Bain WE and McEwan JC and McLean NJ and PL Johnson} } @conference {60969, title = {Current and future impact of DNA technologies on the New Zealand sheep industry}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {69}, year = {2009}, month = {Jun}, pages = {165-168}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {DNA technologies are already widely used in the New Zealand sheep industry. Parentage determination in extensively managed flocks is currently the most widely used test. Increasingly, these tests are being supplemented by the use of performance markers, either by themselves or in conjunction with parentage. Commercial single marker tests currently available in New Zealand include: two for meat yield, two for prolificacy, parasite resistance and production, lamb survival, footrot, scrapie susceptibility, and several monogenic trait tests including: microphthalmia, horns, and spider lamb. However, the future is likely to be some form of {\textquoteright}genomic selection{\textquoteright} where the test explains a major, perhaps majority, of the genetic variation in an animal. This technology depends on the creation and use of high density SNP (single nucleotide polymorphism) probe chips. In New Zealand dairy cattle it is expected to increase the rate of genetic gain by 50 to 70\%. A similar chip has been created for sheep and New Zealand animals are currently being genotyped. If successful the expectation is that industry release will occur in late 2009. New Zealand sheep industry delivery will be as breeding values created using a blend of DNA and existing Sheep Improvement Ltd. information. }, issn = {1176-5283}, author = {McEwan JC} } @conference {60968, title = {Developments in the sheep meat industry: Genetic evaluation of meat yield}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {69}, year = {2009}, month = {Jun}, pages = {161-164}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Sheep Improvement Ltd. has a {\textquoteright}MEAT{\textquoteright} Goal Trait Group which is used to select animals on their genetic merit for meat production. Breeding values are calculated for weight of carcass lean, carcass fat and carcass weight. These breeding values are estimated from live weight and ultrasonic eye muscle dimension data, with the option of incorporating computed tomography (CT) measurements. This served the sheep industry well while carcasses were graded on the basis of carcass weight and GR tissue depth. However, deregulation in the meat industry has seen individual meat processors developing carcass grading systems which not only improve estimates of lean and fat, but also estimate retail yield within individual cuts. SIL have developed a {\textquoteright}MEAT YIELD{\textquoteright} module in response to these changes which estimates breeding values for lean weight in the shoulder, loin and hindleg primal cuts. Meat yield data collected from surplus slaughtered progeny are added to live weight and ultrasonic eye muscle data to predict the breeding values. Slaughter progeny should be randomly selected to avoid biasing the meat yield data. This module is likely to be developed further as additional grading systems are implemented, and equations to translate data into standardised measurements will be required. }, issn = {1176-5283}, author = {Jopson NB and Newman S-AN and McEwan JC} } @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 {41785, title = {Effect of MyoMAX on carcass lean and fat}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {68}, year = {2008}, month = {Jan}, pages = {43-44}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Brisbane, Australia}, abstract = {Previous research has identified quantitative trait loci (QTL) for increased lean meat yield and decreased fat in similar regions of sheep chromosome 2, in New Zealand and Belgian Texels (Broad et al., 2000; Johnson et al., 2005; Laville et al., 2004; Marcq et al., 2002). In the case of the Belgian Texels it has been demonstrated that a single G to A transition ...Continued }, issn = {1176-5283}, author = {Bain WE and PL Johnson and Greer GJ and Dodds KG and McLean NJ and McLaren RJ and Galloway SM and Van Stijn TC and McEwan JC} } @conference {41717, title = {Current status and future of genomic selection}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {67}, year = {2007}, month = {Jan}, pages = {147}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Wanaka}, abstract = {DNA marker test usage is expanding rapidly in the New Zealand livestockindustry. Uptake is already reaching in excess of 30\% of animals in the sire breeding tier for some industries. However, what is confusing to many commercial farmers and advisors is the diversity of claims and uses of these tests and the jargon that surrounds the topic. The aims of the associated Landcorp Speaker presentation and this contract, are to clarify just what DNA markers can do, what work is currently being undertaken, what tests are currently available, and what implications these have for farming systems in New Zealand over the next decade.}, issn = {1176-5283}, author = {McEwan JC} } @conference {41719, title = {Current status of QTL and association studies in New Zealand cattle , sheep and deer}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {67}, year = {2007}, month = {Jan}, pages = {153-159}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Wanaka}, abstract = {In the last 15 years, a series of experiments has beencarried out to search for quantitative trait loci (QTL) in New Zealand cattle, sheepand deer. A QTL represents the position on a chromosome where there is a statistically significant genetic effecton a measured trait. This paper reviews data published so far from these QTL trials and from various association studies. Although the measurement of traits (or {\textquoteleft}phenotypes{\textquoteright}) and the sampling of tissue or fluid for DNA may be complete, the genotyping of DNA isstill incomplete in most studies; further work may be expected as new DNA genotyping techniques and new genomic data become available, and as funds allow. In cattle, we describe the current status of research for carcass composition, meat quality, pubertal traits, milk yield and milk composition traits, and resistance to facial eczema and bloat. In sheep, we include QTL searches for disease traits (resistance to nematode parasites, facial eczema, ryegrass staggers, and footrot), muscling and carcass composition, reproductive traits, wool traits, and lamb survival. In deer, QTL searches have been carried out for live weights, seasonality and pubertal traits, using measurements from an interspecific hybrid. Generally, significant results have been followed further by finemapping and independent validation, before release to industry. Some of the mapping techniques will be described, with examples. So far, QTLs under study in New Zealand have led to the identification and use of gene-tests or marker-tests for meat tenderness and carcass composition in beef cattle, milk yield and composition traits in dairy cattle, and meat yield \%, muscling and litter size genes in sheep.}, issn = {1176-5283}, author = {Morris CA and Campbell AW and Cullen NG and Davis GH and Everett-Hincks JM and Hall RJ and Henry HM and PL Johnson and McEwan JC and Phua SH and Wilson T} } @conference {41970, title = {Developing genomic resources for whole genome selection}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {67}, year = {2007}, month = {Jan}, pages = {148-153}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Wanaka}, abstract = {After more than 20 years of research, genomic technology is now on the cusp of widespread adoption in animal industries. Industry adoption will initially involve improvement of existing breeding and traceability systems. DNA variants, commonly called markers, used in these systems can provide 4 pieces of information: identity, parentage, prediction of an animals genetic worth and its individual performance. The usability of the technology and its adoption is increasing as genotyping prices decline. The major challenges are: to decrease sample collection, processing and reporting costs, and integrate the systems so that all 4 separate pieces of information can be obtained from a single test. Underpinning future research will be availability of sequenced genomes for each of the production species, and large scale {\textquotedblleft}SNP chips{\textquotedblright} derived from them. Currently, the technology provides the ability to identify and map and use variants affecting animal performance in commercial populations. These technologies use existing natural genetic variation already present in the population. The potential of these technologies is safer and more nutritious food produced with less environmental impact and greater animal welfare due to lower level of disease.}, issn = {1176-5283}, author = {McEwan JC} } @conference {41723, title = {Estimation of autumn live weight breeding values in progeny test datasets when progeny are slaughtered to achieve a target carcass weight}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {67}, year = {2007}, month = {Jan}, pages = {175-179}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Wanaka}, abstract = {An analysis was undertaken to investigate how lamb autumn live weight breeding values could be calculated from fixed carcass weight progeny tests (e.g. lambs slaughtered at monthly intervals at a threshold carcass weight). Analysis of growth rate is problematic for this progeny test design as the slaughter groups may experience vastly different environmental conditions, both within and between years. Variance components were estimated from an animal model using restricted maximum likelihood (REML) on data from 11,411 Coopworth progeny records and 126 Coopworth sires. The dataset contained records of weaning weight and live weight at four, five and six months of age (LW4, LW5 and LW6, respectively) collected from 1995 to 2004 in a flock run at Woodlands Research Station. The multivariate mixed linear model included lamb birth day deviation as a covariate, sex of lamb, birth rearing rank, age of dam and live weight contemporary group as fixed effects, and sire as a random effect. The WWT model also had dam fitted as a random effect to give WWT direct and maternal effects (WWTdand WWTm). The analysis was then repeated, but with animals records removed from the dataset once they achieved a threshold weight of 31 and 27kg for ram and ewe lambs, respectively, on data prior to or following linear scaling by contemporary group mean. The heritabilities estimated from the full dataset for WWTd, WWTm, LW4, LW5 and LW6 were 0.30{\textpm}0.03, 0.04{\textpm}0.01, 0.49{\textpm}0.02, 0.49{\textpm}0.02 and 0.51{\textpm}0.02, respectively. These traits were highly correlated with both phenotypic and genetic correlations between the direct traits ranging from 84 to 99\%. The same analysis on the two culled datasets resulted in only minor changes the variance components. The correlation between sire breeding values for autumn live weight (LW6) estimated from the full and the two culled datasets were 98.8\% for both models. Autumn live weightbreeding values can be accurately estimated from datasets which include progressive culling if a multivariate live weight analysis is undertaken, and data from all animals measured at each date are used.}, issn = {1176-5283}, author = {Jopson NB and McEwan JC and Knowler KJ and Wheeler R} } @conference {41707, title = {Genetic technologies for deer breeding}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {67}, year = {2007}, month = {Jan}, pages = {91-94}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Wanaka}, abstract = {The deer industry has made significant progress in developing and applying genetic tools to accelerate genetic gain. This paper briefly outlines the application of current tools (DNA parentage, DNA breed composition and genetic evaluation for growth and velvet), and then suggests a range of other tools which might be used in deer breeding in the future and makes brief comment as to their application. These tools include: genetic evaluation of a wider range of traits; economic indices, mate allocation software, breeding program diagnostic software, enhanced breed composition tests, single gene tests and whole genome selection.}, issn = {1176-5283}, author = {Archer JA and McEwan JC and Hall R} } @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 {41507, title = {Comparison of two-stage selection breeding programmes for terminal sire sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {64}, year = {2004}, month = {Jan}, pages = {212-216}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {Two-stage selection is a technique used in animal breeding to make the use of expensive measurements economically viable in a breeding programme. Selection candidates are first screened using inexpensive, but imperfect, predictors of their genetic merit. A selected subset are then evaluated using more accurate, but expensive, measurements and the final selection is made. This study compared the assessment of carcass composition traits using either computed tomography (CT) scanning or progeny testing (with 10 or 20 progeny per sire; PT10 and PT20, respectively) in the second stage of two stage selection systems using quantitative genetic theory. Stage 1 selection was assumed to be based on live weight and ultrasonic predictions of carcass merit. For a genetic correlation of 0.7 between ultrasonic and CT/PT measures, the economic return peaked for progeny test at $2.70 and $2.38 per commercial ewe when 10 and 5\% of the male selection candidates were evaluated in PT10 and PT20, respectively. CT had a greater return at $3.52 per commercial ewe when 20\% of the male selection candidates were evaluated using CT. The results show that given the moderate heritability of carcass composition traits, the reduction in generation interval and the lower cost of evaluation of CT outweighs the increased accuracy of selection and higher mating ratios associated with progeny testing. }, issn = {1176-5283}, author = {Jopson NB and Amer PR and McEwan JC} } @conference {41479, title = {What the bovine genome project means to New Zealand}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {64}, year = {2004}, month = {Jan}, pages = {86-91}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {The sequencing of the bovine genome commenced in December 2003 and sequencing is planned to achieve a seven-fold coverage by November 2005. This along with previous physical mapping efforts will allow a high quality genomic assembly to be produced. The sequencing is being undertaken by Baylor College of Medicine in Texas. Separately, the Michael Smith Genome Science Centre in Vancouver will sequence 10,000 full length non-redundant bovine mRNAs. The assembled genome will be annotated in collaboration with the Ensembl project at the Sanger Institute, UK, and will be publicly available on genome browsers such as NCBI, Ensembl and UCSC. In the interim the raw sequence information is being made available at NCBI within days of being generated. As well as providing DNA sequence, the program will identify more than 50,000 microsatellites and one to two million SNPs. The availability of this information will transform and accelerate ruminant genomics research. Similar genome sequencing efforts in human and laboratory species have greatly increased the rate of gene variant discovery underlying quantitative trait loci. It will also aid our understanding of gene expression control. New Zealand stands to benefit directly from this work, because of its strong reliance on grazing livestock for export income and its internationally competitive beef and dairy industries. The project is funded by an international consortium involving CSIRO Australia, Genome Canada, New Zealand, National Human Genome Research Institute of the U.S. national Institutes of Health (NHGRI), U.S. Department of Agriculture (USDA), the State of Texas, The Kleberg Foundation, U.S. Beef Council, and Texas and South Dakota Beef Councils. Significantly, the National Institutes of Health have strongly supported the project as a consequence of its human health implications. This project benefited greatly from a previous international genomic collaboration to physically map the bovine genome, and it provides an excellent example of benefits obtained from international research consortia co-investing in public domain infrastructural projects. }, issn = {1176-5283}, author = {McEwan JC and Crawford AM} } @conference {41439, title = {The Alliance Central Progeny Test: Preliminary results and future directions}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {63}, year = {2003}, month = {Jan}, pages = {197-200}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Queenstown}, abstract = {The Alliance Central Progeny Test (CPT) was established in 2001 with the aims of improving the carcass dollar value of sires under the Alliance grading system and establishing links among ram breeders so Alliance can identify the best rams for their clients. In the 2002/2003 season 22 terminal sires from nine different breeds were evaluated. Each ram was mated to 30 ewes at the AgResearch Woodlands research farm. Progeny numbers for each ram ranged from 13-46. Initial early results showed that breeding values for weaning weight were well spread among sires (range over 2.5 kg) indicating there were genetic differences among sires used. Lambs were slaughtered in four slaughter groups between December 16th , 2002 and March 11th , 2003. Analyses from the full data set will be available from May 2003. The next cycle of the Alliance CPT begins with mating in April, 2003, with an emphasis on dual-purpose sires.}, issn = {1176-5283}, author = {Campbell AW and Knowler K and Behrent M and Jopson NB and Cruickshank G and McEwan JC and Wilson T} } @conference {41346, title = {Dynamic selection for sheep genetic improvement}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {62}, year = {2002}, month = {Jan}, pages = {188-190}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {Dynamic selection is a process used in livestock improvement programmes to maximise genetic progress while constraining the long term rate of inbreeding. An optimisation algorithm identifies proportions of genes each selection candidate should contribute to the next generation. Application of dynamic selection procedures to select cull and replacement ewes, and then subsequently to select a ram team, was demonstrated using data from a Romney sheep breeder. When compared with selection based on an index of breeding values alone, dynamic selection of cull and replacement ewes reduced the accumulation of relatedness by approximately 85\% of the average annual accumulation from 1994 to 2000. To achieve this, approximately 33\% of the average annual genetic progress in average index value was sacrificed. Using dynamic selection to identify a ram team to be mated to selected ewes resulted in a saving in relatedness by an amount equal to the average annual accumulation from 1994 to 2000 with only a very modest drop in genetic progress of 9\% of the average annual genetic progress in average index value. This study has demonstrated that dynamic selection tools could, when practically applied to sheep breeding populations, provide a transparent and efficient means of managing the tradeoff between rate of genetic progress and rate of accumulation of relatedness. }, issn = {1176-5283}, author = {Amer PR and Jopson NB and McEwan JC} } @conference {41186, title = {Differences in wool characteristics in lines of sheep with high or low levels of backfat thickness}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {159-161}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {Relationships between backfat thickness and wool characteristics for lines of Coopworth and Southdown sheep, selected for or against backfat thickness, were studied between years and between different age classes. On average, the lean Coopworth line grew 230 g more greasy wool (P < 0.001), which was 1.7 {\textmu}m finer (P < 0.001) and less variable in diameter (P < 0.05) than the fat line. Other measured wool characteristics were not affected. The Southdown lines did not differ in fibre diameter, variability of diameter or curvature, within age groups. Southdown lambswool was finer (P< 0.001) than hogget or ewe wool (23.6 {\textpm} 4.9, 27.0 {\textpm} 5.6 and 26.7 {\textpm} 5.4). Fibre diameter differences observed in the Coopworth lines may have been a founder effect, as subsequent selection had little impact on it. Selection for leanness increased greasy fleece weight without affecting fibre diameter or staple length. }, issn = {1176-5283}, author = {Merrick NC and Baird DB and McEwan JC and Purchas RW} } @conference {41156, title = {Lamb and ewe performance of East Friesian x Coopworths relative to pure-bred Coopworths}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {47-50}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {Purebred East Friesians (EF) sires were used in both the 1996 and 1998 matings (n=2 and 4, respectively) to generate 62 and 66 progeny for the two years. These animals were compared with approximately 1000 COOP lambs in each year for growth, ultrasonic fat and muscle depths, wool, dagginess, host resistance to internal parasites, and reproductive performance. For the 1998 mating, one F1 sire and 24 F1 dams were mated to COOP ewes and rams respectively to produce approximately 73 paternal and 33 maternal backcross progeny. Twenty four EF cross ewes were mated in each of the 1998 and 1999 birth years, and reproductive performance recorded. On average, the EF cross progeny had a live weight advantage (P0.05) after adjustment for live weight, but EF cross progeny had significantly lower C and GR measurements. EF cross progeny had lower fleece weight at 12 months (-0.46kg; P<0.001) than COOP. Average dag score differed between sire breeds with EF cross having lower scores (0.4 verses 1.2) compared to COOP. Sire breed differences in resistance to parasites were not significant. Analysis of the limited EF backcross data indicated positive EF direct and maternal effects for weaning weight, negative EF direct effects for dag scores, and negative EF direct and maternal effects for fleece weight. EF cross ewes performed significantly better (P<0.001) in lambs born per ewe lambing than the purebred COOP for both 2-tooth (2.57 cf. 1.84) and mixed-age (2.76 cf. 1.98) classes. The high lambing percentage in EF cross ewes meant that more than 70\% of mixed-age ewes had three or more lambs per lambing, which could result in management difficulties. There was significant overlap in the sire-breed ranges for all traits, meaning selection of sire was more important than breed selection. }, issn = {1176-5283}, author = {Jopson NB and Dodds KG and Knowler KJ and Wheeler R and McEwan JC} } @conference {41160, title = {Lamb survival traits in Coopworth sheep selected for high or low backfat depth}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {61-64}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {Consumer preferences for lean healthy meat have driven genetic selection for leanness in the terminal sire and dual purpose sheep industries over the last 20 years. The Invermay Coopworth lean and fat selection lines were established in 1980 to study the effects of selection for live weight adjusted leanness on carcass traits, and the correlated responses in other traits. This paper reports the findings of two year{\textquoteright}s data on lamb survival and performance in the lean and fat selection lines. Records were collected from 817 lambs comprising 325, 337 and 155 from the fat, lean, and a random-bred control line, respectively. Neo-natal mortality was not significantly different between the three lines, with approximately 93\% of lambs born surviving until tagging. Lamb survival from tagging until weaning differed significantly between the selection lines (P<0.05), with fat line animals having 10.9\% better lamb survival than lean line animals (95.5 verses 84.6\%), after adjusting for differences in year, birth weight, birth rank, skin thickness, wool length, age of dam, mothering ability and ewe udder volume. Fat line lambs were 0.9 {\textpm} 0.1kg (mean {\textpm} SEM) lighter than lean line animals, with control line animals intermediate. Udder volume (as measured by water displacement) did not differ between the three lines. Mothering ability (as measured by distance from ewe to the new born lamb during handling in the field) did not differ significantly between the lean and fat lines. Fat line lambs had thicker skins than lean line lambs at the same birth weight (P<0.01), but had no difference in wool length. The differences in lamb mortality between the lean and fat lines cannot be fully explained by differences in birth weight, indicating some physiological difference between the lines affecting survival. }, issn = {1176-5283}, author = {Jopson NB and Greer GJ and Bain WE and Findlay JA and McEwan JC} } @conference {41172, title = {Search for a locus near to myostatin that increases muscling in Texel sheep in New Zealand}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {110-112}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {In close collaboration with three Texel breeders, we initially genotyped 36 rams with 5 DNA microsatellite markers that are known to map around the myostatin gene in sheep. Of these 36 rams, progeny of 12 polymorphic sires (4 from each flock) were selected for further analysis. This selection was made on the basis of each sire producing more than 40 offspring which were accompanied by parentage records, live weights at weaning and 8 months of age, and ultrasonic measurements of fat depth and rib-eye muscle dimensions. Final progeny numbers from the sires chosen ranged from 45 to 115 per sire. The data was analyzed by regressing the observed measurements on the probability of which paternal grandparental chromosome was inherited at the myostatin locus. The results suggest that the region of the sheep genome near the myostatin locus affects muscling (P<0.05) and fat depth (P<0.05) in the progeny of 4 of 12 sires tested. }, issn = {1176-5283}, author = {Broad TE and Glass BC and Greer GJ and Robertson TM and Bain WE and Lord EA and McEwan JC} } @conference {41196, title = {The Sheep Improvement Limited (SIL) genetic engine}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {195-197}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {The Sheep Improvement Limited (SIL) genetic engine (GE) interfaces with the SIL national database. It calculates breeding values from data provided by the database and reports these back to the database along with adjusted deviations and genetic trends graphs. The SIL system is a distributed and modular design, with the database and the GE located on separate computers connected via the Internet. The individual GE components are also modular and version 2 consists of 6 separate goal trait modules: growth, meat, wool, reproduction, survival and host resistance to internal parasites. This modular design allows each goal trait module to be easily upgraded and additional modules can be added as required. The GE uses across flock and year multivariate animal model BLUP. Evaluations can be requested as required by the user via Internet access to the database. The size of the job submitted scales transparently up to requests involving more than 200,000 animals, sufficient for the largest across flock sire referencing schemes. The intention is that the system will be continuously extended and improved. Near term developments are likely to extend to across breed analyses, the inclusion of a facial eczema module, and improved diagnostics. In the longer term it is anticipated that information from genetic markers will be included. }, issn = {1176-5283}, author = {Newman SA and Dodds KG and Clarke JN and Garrick DJ and McEwan JC} } @conference {41016, title = {Cost-benefit analysis of commercial use of the Inverdale prolificacy gene}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {58}, year = {1998}, month = {Jan}, pages = {157-160}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The Inverdale prolificacy gene is one of several potential major genes currently being explored for commercial application to the New Zealand sheep industry. We calculated economic benefits of two strategies to breed Inverdale carrier stud rams using gene flow methodology. Strategy 1 involves continuous transition matings from a conventional stud flock to generate Inverdale carrier ewes while Inverdale carrier ewes are self replacing in Strategy 2. Strategy 1 involved less DNA testing per ram sold, resulting in a $140 saving in testing costs at $50 per test. Reduction in conventional genetic response was also lower for Strategy 1 (<5\% as opposed to 24\% for Strategy 2) although Strategy 1 requires closer monitoring of animal identification and some Inverdale rams must be kept to produce carrier ewes. Commercial Inverdale use was shown to be highly beneficial in an existing terminal sire mating system with an added value over a normal ram of $3350 per Inverdale ram purchased. This was also highly cost effective with an expected DNA test price of $50 to $75 per sheep genotyped. }, issn = {1176-5283}, author = {Amer PR and McEwan JC and Dodds KG and Davis GH} } @conference {40964, title = {Finding QTL{\textquoteright}s without markers: experience with FINDGENE.}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {57}, year = {1997}, month = {Jan}, pages = {290-294}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {FlNDGENE is a mixed inheritance model computer program which can analyse extensive animal pedigrees. It partitions the observed variance into fixed effects. polygenic inheritance, a two allele major locus effect and a residual envimnmental variance. It do-es not require genotype information. Data from three New Zealand sheep experiments where faecal nematode egg count (FEC) information had been collected were examined by this method. They included a long term selection experiment for FEC in Rornneys at Wallaceville, another in Perendales at Ruakura, and a randomly mated Coopworth flock at Woodlands Research Station. All PEC traits were initially transformed using the function log.(x+lOO). The final model included the effect of sex/year contemporary group, birthday and polygenic inheritance in addition to a 2 allele Mendelian gene effect. Results from all three data sets suggested a dominant a{\textquoteright}utosomal gene for host susceptibility was affecting strongyle PEC values in the summer/autumn period with estimates of 0.37,0.69 and 0.72 log eggs/g for the single allele effect from Romney, Perendale and Coopworth flocks respectively. Corresponding values for dominance were 0.47,0.44 and 0.88 log eggs/g with susceptible allele frequency 0.14.0.55 and 0.69. When considered together, these results suggest that at least one QTL is affecting the development of host resistance to internal parasites in young sheep. The identification and characterisation of this QTL may result in useful novel methods of internal parasite control.}, issn = {1176-5283}, author = {McEwan JC and Morris CA and Bisset SA and Kerr RJ} } @conference {40739, title = {Discovery of the Inverdale gene (FecX)}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {55}, year = {1995}, month = {Jan}, pages = {289-290}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Selection for ovulation rate in a screened prolific flock identified a prolific family of Romneys in 1984 that descended from one ewe, and progeny tests for her male descendants carried out from 1985 to 1990 indicated the presence of a major gene (Inverdale) on the X- chromosome. One copy of the gene increases ovulation rate by about 1.0 and litter size by about 0.6. However, research in 1991 found that ewes with two copies of the gene have small non-functional {\textquoteright}streak{\textquoteright} ovaries and are infertile. Many of these infertile ewes develop tumour-like structures on their ovaries and these are currently the subject of intensive research. In 1993 a prolific Romney flock in Tokoroa, with no known connection with A281, was also found to have the Inverdale gene. The place of the Inverdale gene in industry will be to increase prolificacy in ewe flocks mated to terminal sires, and a research programme has been established to identify a genetic market for ram breeders. }, issn = {1176-5283}, author = {Davis GH and McEwan JC and Fennessy PF and Dodds KG} } @conference {40740, title = {Elucidation of the genetic nature of the Inverdale gene (FecX): Segregation with a twist}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {55}, year = {1995}, month = {Jan}, pages = {291-293}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {A major gene, affecting a quantitative trait in farmed livestock, is usually detected by observing segregation of the gene within families such as half-sib sire families. In the case of the Inverdale, a maternal family was observed to contain some highly prolific ewes. Progeny testing of four rams from this family revealed two rams with prolific progeny, but segregation amongst these progeny was not apparent. The data appeared to be consistent with the hypothesis of an X-linked major gene, but were not conclusive. A further progeny test involving six sons and five maternal grandsons of a putative Inverdale ram was undertaken. Three of the maternal grandsons but no sons had prolific daughters, confirming the X-linked hypothesis. Further major gene searches should consider X-linked as well as other modes of inheritance. The mode of inheritance, and effect of one and two copies of the Inverdale gene, have important consequences for its use in research and production. }, issn = {1176-5283}, author = {Dodds KG and Davis GH and McEwan JC and Fennessy PF} } @conference {40743, title = {Industry use of the Inverdale gene (FecX)}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {55}, year = {1995}, month = {Jan}, pages = {298-300}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The Inverdale gene (FecX) offers the sheep industry the potential to markedly increase production at little cost. However, the characteristics of the gene mean that appropriate breeding structures are essential. The recommended structure is a stratified crossbreeding system. The three tier breeding structure consists of: (1) a ram breeder producing rams known to carry the Inverdale gene; (2) a ewe breeder producing carrier ewes by mating carrier rams across dual purpose breed ewes; and (3) a lamb producer who mates a meat breed ram with carrier ewes to produce lambs for slaughter. Some farmers may choose to have two, or all three tiers on a single property. If the gene was used to maximum extent possible in Romney and Romney derived breeds, some 40\% of all breeding ewes would contain a single copy of the gene and these would produce 31\% more lambs for sale per ewe mated. Conservative estimates of the benefits to the New Zealand farmer are approximately $29m per annum. }, issn = {1176-5283}, author = {McEwan JC and Davis GH and Fennessy PF and Dodds KG} } @conference {40753, title = {Sires for more valuable lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {55}, year = {1995}, month = {Jan}, pages = {324-326}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Specialist terminal sire breeds offer several advantages to the commercial farmer, particularly their ability for rapid change in relevant traits in response to market signals. The production, survival and disease resistance benefits resulting from the hybrid vigour in the crossbred progeny have also widely documented. Terminal sires breeds also provide for efficient utilisation of between breed differences in carcass quality and mature weight. However, terminal sires are presently under utilised by the NZ sheep industry. In future this situation is expected to change. Long term trends suggest that carcasses will be paid for on the basis of weight of lean meat. In addition, terminal sire breeders are increasingly using performance recording systems allied with methods of estimating carcass composition, both of which have markedly improved in recent years. Terminal sire breeds are the logical method to distribute major genes affecting growth and carcass quality. The identification, characterisation and "packaging" of these genes will become increasingly routine. }, issn = {1176-5283}, author = {McEwan JC and Davis GH and Fennessy PF and Clarke JN} } @conference {40524, title = {Heritability of ultrasonic fat and muscle depths in Romney sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {53}, year = {1993}, month = {Jan}, pages = {347-350}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Twelve buffalo (5 bulls \& 7 steers) at c.33 mo of age were compared with 16 Friesian cross cattle (6 bulls \& 10 steers) at c. 29 mo of age. The 2 species had not been run together, but were slaughtered and processed concurrently. Carcass weights were unaffected by species or castration (mean=258.6 kg). Relative to cattle, buffalo had shorter carcasses, higher dressing-out percentages, greater fat depths, more kidney and pelvic fat, and lower eye-muscle areas (all P<0.01). Buffalo had heavier hearts and spleens (P<0.001), and lighter livers and weights of rumen digesta (P<0.001). Buffalo rumen digesta contained fewer particles over 4.0 mm, but the size of particles in the abomasum was similar for both species. Yields of commercial cuts did not differ between buffalo and steers, but cattle steers had more fat trim, less meat, heavier striploins, and a higher ratio of hind-to forequarter meat than bulls (all P<0.05). Relative to the cattle, buffalo carcasses had lighter inside and cube roll cuts, but heavier outside flats, more fat trim, and a higher proportion of forequarter meat (all P<0.05). Buffalo fat was less yellow. Ultimate pH of cube-roll (M. longissimus) samples were higher for bulls than steers within cattle, and higher for cattle than buffalo (each P<0.05), possibly because the buffalo had been handled more. Other quality differences that could have been pH-related were the lower shear values (indicating more tender meat) and lower water-holding capacity (each P<0.01) of buffalo meat. However, colour (L*, a*, b* values), and sarcomere lengths were similar. Intramuscular fat levels were similar for meat from buffalo and cattle steers, but were much lower for bull beef. This is the first set of cattle/buffalo comparative data for carcass and meat quality collected under New Zealand conditions and will be of value when evaluating the role of Buffalo in this country.}, issn = {1176-5283}, author = {McEwan JC and Clarke JN and Hickey SM and Knowler KJ} } @conference {40528, title = {How reliable are sheep pedigrees?}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {53}, year = {1993}, month = {Jan}, pages = {363-370}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Ligand blotting analysis of serum from the horse using radiolabelled IGF-I revealed a protein at 96 kDa which was not present in serum from goat, cow, sheep, deer or donkey. These latter species all displayed five labelled bands in the range 24 to 41 kDa. Conversely these were only weakly labelled in serum from the horse. Size exclusion chromatography of horse serum pre- incubated with radiolabelled IGF-I revealed reduced binding in the 130 kDa peak compared with goat plasma and ligand blotting analysis indicated that 96 kDa protein was present in this peak. The 96 kDa protein from horse serum binds IGF-I and IGF- II specifically and appears to be unique to this species. The nature of this protein is at present unknown.}, issn = {1176-5283}, author = {Crawford AM and Tate ML and McEwan JC and Kumaramanickavel G and McEwan KM and Dodds KG and Swarbrick PA and Thomson P} } @conference {40526, title = {Investigation into the possibility of a major gene for fleece weight in screened sires}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {53}, year = {1993}, month = {Jan}, pages = {355-358}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {This study investigated the effect of a progesterone containing intravaginal CIDR (Controlled Internal Drug Releasing) device on plasma progesterone and luteinizing hormone (LH) concentrations during 14-day device insertion and the subsequent oestrous cycle of fallow deer (Dama dama). Blood samples were collected from 4 entire does at 20 minute intervals for periods of 8-12h on three occasions following device insertion (i.e. insertion, mid-treatment and withdrawal) and on Days 0, 5, 12 and 19 of the subsequent oestrous cycle. Plasma was analysed for progesterone and LH concentrations by radioimmunoassay. Plasma progesterone values were elevated (>6 ng/ml) and LH values reduced (<1 ng/ml) during device insertion relative to pre-insertion values. Plasma LH concentrations were highest on Day 0 of the oestrous cycle, with a marked increase in the pulse amplitude. One doe exhibited a pre-ovulatory LH surge. Plasma progesterone increased from <0.5 ng/ml on Day 0 to 1.5-4.2 ng/ml on Day 12 (luteal phase) and high amplitude progesterone pulses were exhibited by all does on Day 19 (onset of luteolysis). The study has demonstrated that CIDR devices deliver sufficient progesterone to inhibit ovulation and the declining plasma LH concentrations during device insertion support a hypothesis of negative feedback by progesterone on LH secretion.}, issn = {1176-5283}, author = {Wuliji T and Dodds KG and Fennessy PF and Andrews RN and McEwan JC and Turner P and Wheeler R and Hawker H} } @conference {40415, title = {Comparison of growth, hogget fleece weight and reproductive traits of three sheep breeds from a flock selected for prolificacy and a Romney control flock}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {52}, year = {1992}, month = {Jan}, pages = {211-216}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The total glucose concentration of a medium changes with the extent of serum supplementation, and this may have an effect on embryonic development in vitro. In this study, 1- and 2-cell sheep embryos (N+109) were cultured for approximately 120 hours at 39 C under humidified 5\% CO2, 5\%)2 and 90\% N2 in Synthetic Oviduct Fluid medium (SOF) supplemented with 20\% human serum and a total glucose concentration of either 1.5 mM (modified-SOF) or 2.3 mM (unmodified-SOF). A slight effect was observed on the proportion of embryos developing to at least the expanded blastocyst stage (63\% and 48\% for modified-SOF and unmodified-SOF, respectively, P<0.1). Twenty-eight blastocysts from each treatment were selected and transferred to 28 synchronised, mature ewes (2 blastocysts per ewe). Pregnancy and number of foetuses were determined by ultrasonography 54 days after transfer. All ewes were pregnant and survival of embryos was 82\% and 71\% for modified-SOF and SOF, respectively. However, a high post-natal mortality rate was observed (37\%), which was mostly attributed to a relatively high birthweight of dead lambs (6.4 }, issn = {1176-5283}, author = {McEwan JC and Davis GH and Dodds KG and Fennessy PF and Clarke JN and Bruce GD and Hishon MG} } @conference {40375, title = {Effect of selection for productive traits on internal parasite resistance in sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {52}, year = {1992}, month = {Jan}, pages = {53-56}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The distribution of condensed tannins (CT) in plants, their mode of action and benefits to ruminant nutrition are briefly reviewed. Data are presented showing the CT in lotus species reduced rumen degradation of protein and increased its flow to the intestine, but an increased amino acid absorption only occurred with Lotus corniculatus, suggesting the CT in Lotus pedunculatus prevented enzymic hydrolysis of the protected protein. The extent to which CT in Lotus pendunculatus depressed nitrogen (N) digestion was similar when fed as a sole diet and when fed as a third of the diet with pasture. The implications of these results are that both concentration and type of CT are important in affecting nutritive value, and that these factors need to be resolved before an effective plant selection program can be undertaken. }, issn = {1176-5283}, author = {McEwan JC and Mason P and Baker RL and Clarke JN and Hickey SM and Turner K} } @conference {40247, title = {Comparison of growth and carcass traits of ram lambs of three breeds from a flock screened for prolificacy and a Romney control flock}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {50}, year = {1990}, month = {Jan}, pages = {397-402}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {This paper reviews the application of intraruminal chromium controlled release capsules (CRC, Captec (NZ) Ltd, Auckland) to the measurement of herbage intake in ruminants. The capsules are designed to provide for the linear release of Cr2O3 over c. 25 days in sheep and c. 20 days in cattle. Uniform release of Cr2O3 is achieved 2 to 3 days after oral administration of the CRC but steady state levels of Cr2O3 in the faeces are usually not achieved until day 7 or 8 in sheep and day 5 or 6 in cattle. Where cross-over or multiple feeding level experimental designs are applied, time should be allowed for Cr2O3 to adjust to a new steady state in the faeces before sampling for each new treatment. The period of time required varies from 3 to more than 5 days depending on the size of feed intake change. The continuous mode of marker release in the rumen reduces diurnal variation of Cr2O3 in the faeces and this allows rectal sampling regimens to be applied at different times of each sampling day. Sward sampling of faeces reduced disturbance of animal grazing to a minimal level since Cr2O3 is delivered by a single CRC application. The effects of level of feed intake and feed type on the rate of Cr2O3 release are usually small, but release rates may be up to 13\% lower in rumen-fistulated than in non-fistulated animals and may differ for capsules of the same time applied to different ruminant species. Reduced animal handling, flexible faecal sampling times and lower labour requirements with CRC technology, compared to daily drenching of Cr2O3, enable the number of experimental animals to be increased. This improves the likelihood of detecting differences in mean intake between groups. Intakes of individual animals will not be reliably estimated with chromic oxide CRC until the digestibility of herbage consumed by individual animals can be measured more accurately. }, issn = {1176-5283}, author = {McEwan JC and Davis GH and Dodds KG and Fennessy PF and Clarke JN and Hishon M} } @conference {40233, title = {Wool production and other characteristics of progeny from high performance Coopworths x Romney rams}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {50}, year = {1990}, month = {Jan}, pages = {305-310}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Masked by the short-term influences of under or over-production at national level, concerns about the quality and hygiene of animal products and fears regarding dietary influences on human health, long- term projections of what will be expected of the pastoral animal industries are difficult to make. Concerns about the welfare of animals in intensive systems coupled with the political changes taking place in Russia and Eastern Europe are likely to swing animal production more towards pastoral systems. The removal of large quantities of fat from the food chain is likely to become a permanent feature. So too is the trend for a more even flow of high-quality products on to the market. In meeting these goals the role of the current biotechnological revolution, both directly in primary animal production, and indirectly through its contribution to the animal-product and food-processing industries, will be essential. We can not afford intellectual scientific complacency in a world where famine could, however remotely, become a truly global phenomenon. It is against this background that those aspects of the pastoral animal industries that currently limit production are viewed and the opportunities for implementing new technologies outlined. }, issn = {1176-5283}, author = {Andrews RN and Dodds KG and McEwan JC and Wuliji T} } @conference {40151, title = {Ultrasonic fat depths in Romney lambs and hoggets from lines selected for different production traits}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {49}, year = {1989}, month = {Jan}, pages = {113-120}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Forty four feral males, 30 Saanen males and 20 Saanen females, all yearling or younger, were slaughtered and their chemical and dissectible composition determined. The ferals, reared on hill country, were leaner than the Saanens reared on better grazing. Females tended to be fatter than males in most measures of fatness. All three groups were low in fat, both total chemical fat, and dissected fat in the leg. The fat content of lean tissue was extremely low.}, issn = {1176-5283}, author = {McEwan JC and Clarke JN and Knowler MA and Wheeler M} } @conference {40086, title = {Growth and carcass traits of purebred Texel and Suffolk sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {48}, year = {1988}, month = {Jan}, pages = {41-48}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {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.}, issn = {1176-5283}, author = {McEwan JC and Hanrahan JP and Fitzsimons JM and Allen P} } @conference {40119, title = {Production and characteristics of wool from the hogget progeny of sheep intensively screened for fleece weight}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {48}, year = {1988}, month = {Jan}, pages = {207-212}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {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{\textquoteright}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.}, issn = {1176-5283}, author = {Hawker H and Dodds KG and Andrews RN and McEwan JC} } @conference {40061, title = {Reproductive performance of progeny of prolific Romney, Coopworth and Perendale sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {47}, year = {1987}, month = {Jan}, pages = {89-91}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {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.}, issn = {1176-5283}, author = {Davis GH and McEwan JC and Howarth MV and Kelly RW and Paterson AT} } @conference {39963, title = {Effect of herbage allowance on the productive performance of lactating and non-lactating hoggets}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {45}, year = {1985}, month = {Jan}, pages = {147-150}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {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.}, issn = {1176-5283}, author = {McEwan JC and Mathieson CD and Hawker H} } @conference {39928, title = {Selection for productive traits on back fat depth in ewe lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {44}, year = {1984}, month = {Jan}, pages = {249-252}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {No abstract supplied.}, issn = {1176-5283}, author = {McEwan JC and Fennessy PF and Clarke JN and Hickey SM and Knowler MA} } @conference {39819, title = {Date of lambing and sheep production during lactation in Southland}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {43}, year = {1983}, month = {Jan}, pages = {45-48}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {In a series of 10 trials involving over 5000 lactating dairy cows, animals inseminated when detected in oestrus from 3 days after an injection of a prostaglandin F2a (PGF) had an average pregnancy rate of 68\% compared to 59\% in untreated herdmates. The variation in the post injection interval to oestrus necessitated detecting oestrus before the PGF-related fertility effect could be repeatedly demonstrated. When a synthetic analogue of gonadotrophin releasing hormone (GnRH) was injected before PGF in an attempt to reduce the variation in this injection-to-oestrus interval, the opposite effect occurred, the average interval was increased by 3 days (4.13 v 7.03) and the PGF-related fertility effect was eliminated. A second trial with GnRH confirmed that an injection of this hormone had an effect on the corpus luteum which prevented complete luteolysis by PGF. This interaction between GnRH and the corpus luteum was studied in 3 further trials in which GnRH was injected once at from 1 to 13 days post insemination. Positive fertility effects were observed in each trial, but they were not consistent. Nonetheless, the strategic use of these 2 types of hormones offer prospects for significantly increasing pregnancy rates to first insemination in lactating dairy cows.}, issn = {1176-5283}, author = {McEwan JC and Mathieson C and Hawker H} } @conference {39865, title = {Ewe live weight, level of pasture feeding and live-weight gain}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {43}, year = {1983}, month = {Jan}, pages = {225-228}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The following farmer observations are based on limited numbers and are really a plea for more accurate work to be done. Loss from dags is difficult to cost but nationally it probably runs into millions in devalued wool and extra labour. On my own farm the direct loss is estimated to be about 63 cents/stock unit/annum. To reduce this loss I have looked at the following practices: 1. Breeding, limited observations - nil results. 2. Drenching. In two-tooths a drench pretupping reduced dags 44\% in a 3 month period. 3. Docking tails longer was inconclusive, possibly due to a limited difference between {\textquoteright}long{\textquoteright} and {\textquoteright}short{\textquoteright} tails. 4. Mules operation. Result a 50\% reducing between January and May. Mulesed sheep are easier to crutch by hand or machine. Sheep were apparently not knocked about by the operation. Although gory, mulesing is preferable to flystrike in terms of suffering. Uninformed and emotional public opinion is a problem. The greatest benefit of dag control or elimination may come from reduced flystrike.}, issn = {1176-5283}, author = {Thompson KF and McEwan JC and Kelly RW and Crosbie SF} } @conference {39666, title = {Pasture allowance and lamb growth}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {40}, year = {1980}, month = {Jan}, pages = {92-97}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, issn = {1176-5283}, author = {Thompson KF and McEwan JC and Risk WH} }