@article {3672, title = {Preliminary investigations into genetic variation in distance travelled by young sheep}, journal = {New Zealand Journal of Animal Science and Production}, volume = {81}, year = {2021}, month = {01/2022}, pages = {63-67}, address = {Online}, abstract = {In pastoral grazing systems, animals need to walk to obtain nutrients (pasture) and water, however, it is also thought that the distance an animal travels is further influenced by factors including the grazing behaviour of the animal, its health status and its general motivation for moving. The purpose of this research was to investigate the repeatability and genetic variation in the trait of distance travelled for New Zealand sheep. Data were collected using global positioning satellite (GPS) collars fitted to 422 animals from three different groups of animals (Group). The animals were allowed ad libitum grazing. Progeny from 44 sires were represented in the data set. The GPS collars were fitted for up to 17 days. Given between-day variability in distance travelled depending on paddock attributes (size and feed availability) all data were scaled to a constant mean. A univariate repeated measures model was fitted to the data using ASREML, with Group fitted within the model, and day within Group fitted as the repeated measure. The heritability estimate for daily distance travelled was 0.36{\textpm}0.09, with a repeatability estimate of 0.51{\textpm}0.03. The results indicate that distance travelled is a repeatable trait at the individual animal level and is under moderate genetic control. Keywords: sheep; GPS; distance travelled}, issn = {1176-5283}, author = {PL Johnson and Cullen N and Hickey SM and Knowler K and Bryson B and Hall M and Pletnykov P} } @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} } @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 {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 {89247, title = {Some lessons from using zinc-salt treatments to protect dairy cows against facial eczema}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {73}, year = {2013}, month = {Jan}, pages = {171-174}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {

A trial at AgResearch Ruakura, evaluating two different methods of administering zinc++(Zn) salts to protect cows from facial eczema, was carried out in lactating dairy cows to study the variation in concentrations of blood Zn++. The treatments were: continuous supply of zinc sulphate (ZnSO4) through water troughs (n = 10 cows), versus daily oral drenching with zinc oxide (ZnO) (n = 10 cows). Responses in daily milk yields, and concentrations of Zn++in blood were recorded twice weekly over four weeks for each cow. The ZnSO4trough treatment took ten days for blood Zn++concentrations to equilibrate, after which the sampling-day average ranged from 20{\textendash}26 μmol/L. Between-cow repeatability was 0.42 {\textpm} 0.15. The daily ZnO treated cows equilibrated after drenching for three days. Average blood Zn++concentrations then ranged from 24{\textendash}29 μmol/L. Between-cow repeatability was 0.44 {\textpm} 0.17. Dailymilk yields did not differ significantly between treatments. Target ranges for blood Zn++concentrations to provide protection against facial eczema in lactating dairy cows of 18{\textendash}34 μmol/L were published 26 years ago. These may need to be re-assessed, with changes in breed composition and increases in milk yield over that time within the national herd.

}, issn = {1176-5283}, author = {Morris CA and Hickey SM} } @conference {79018, title = {Genetic and phenotypic relationships among flystrike indicator traits in the Earnscleugh stud Merino flock}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {192-195}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Increases in breech wrinkles, breech cover and dags have been shown to increase flystrike susceptibility of Merino sheep. At shearing at approximately 320 days of age in 2007, 2008 and 2009, breech wrinkle (1 to 5), dag score (1 to 5) and breech cover (1 to 5) were scored on 736, 806 and 866 yearlings that were the progeny of 31, 38 and 36 sires respectively. It was hypothesised that flystrike would become worse with an increasing score, where 5 indicated a very wrinkly, very daggy or very woolly breech. Fleece weight was recorded at shearing and fleece midside samples were collected and measured for washing yield. Breech wrinkle score (h{\texttwosuperior} = 0.25 {\textpm} 0.07), breech cover (h{\texttwosuperior} = 0.33 {\textpm} 0.08) and dag score (h{\texttwosuperior} = 0.10 {\textpm} 0.04) were found to be heritable. Breech wrinkle score and breech cover were phenotypically (0.39 {\textpm} 0.02, P < 0.05) and genetically correlated (0.40 {\textpm} 0.16, P < 0.05). Clean fleece weight was heritable (h{\texttwosuperior} = 0.33 {\textpm} 0.06) and showed a strong significant negative genetic correlation (-0.52 {\textpm} 0.14, P < 0.001) with breech cover. There was no evidence of flystrike during the three years of investigation, but this stud could decrease susceptibility by decreasing breech cover, breech wrinkles and dag score}, issn = {1176-5283}, author = {Scobie DR and Hickey SM and Campbell AK and Maslen DP} } @conference {78986, title = {Variation of milk composition traits among Holstein-Friesian-sired cows}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {58-62}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {

A pooled afternoon and morning milk sample was obtained from each of 3,789 cows of known pedigree during a standard herd-test carried out in 21 North Island spring-calving herds between November and February. The cows were all sired by one of 11 Holstein-Friesian bulls, in a sampling design intended to sample milk from many daughters per sire, for segregation studies. Routine herd-test data consisted of 24 hour milk yield, protein \%, fat \% and somatic cell count. Samples were measured at Ruakura for fatty acid composition, fat melting point, and the concentrations of the following components, lactoferrin, β-lactoglobulin, β-casein, κ-casein, and total carotenoids. After liaison between AgResearch Ruakura staff and each dairy farmer a variate describing the current grazing groups of cows were included in analyses. Coefficients of variation were calculated for each milk component, and ranged from 0.04 to 0.35. Phenotypic correlations among components were estimated. The correlations were negative between the percentage of mono-unsaturated fatty acids present in milkfat and both the protein \% (-0.26 {\textpm} 0.03 (standard error)) and fat \% (-0.38 {\textpm} 0.02) of the milk. Some implications of selection mainly for yield from cows at pasture are discussed in terms of likely effects on milk composition.

}, issn = {1176-5283}, author = {Cullen NG and Hickey SM and Morris CA} } @conference {75890, title = {BRIEF COMMUNICATION: Phenotypic selection of cows for lactation persistency}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {136-138}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {Lactational persistency is the degree to which early lactation yield persists during the lactation season. Though this is a desired dairy performance trait, it has not been directly selected for in New Zealand dairy populations. In spring-calving pasture-fed cows, peak lactation is reached soon after calving and then declines by about 10\% per month (Davis et al., 2000) until the cows are... Continued}, issn = {1176-5283}, author = {Hickey SM and Singh K and Morris CA and Henderson HV and Molenaar AJ} } @conference {75916, title = {Genetic and phenotypic relationships between flystrike indicator traits in a stud Merino flock}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {251-256}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {

Increasing breech wrinkles, breech cover and dags increase flystrike susceptibility of Merino sheep. Urine stain has been implicated in flystrike, although there is a paucity of data. At tail docking in 2007, 2008 and 2009 on a property breeding Merino rams, breech wrinkle (1 to 5) was scored on 238, 202 and 337 lambs that were the progeny of 12, 9 and 9 sires respectively. Dag score (0 to 5), urine stain (0 to 5) and breech cover (1 to 5) were scored at 100 days of age. Breech wrinkle score (h{\texttwosuperior} = 0.51 {\textpm} 0.11) and breech cover (h{\texttwosuperior} = 0.27 {\textpm} 0.08) were heritable, and phenotypically (0.16 {\textpm} 0.04, P \<0.05) and genetically correlated (0.77 {\textpm} 0.14, P \<0.05). Dag and urine stain scores were skewed towards low scores and the heritability estimates for these traits were low (h{\texttwosuperior} = 0.08 {\textpm} 0.07 and 0.04 {\textpm} 0.06 respectively). Yearling clean fleece weight was heritable (h{\texttwosuperior} = 0.28 {\textpm} 0.13) and genetically correlated with breech cover (-0.62 {\textpm} 0.26, P \<0.05). There was no evidence of flystrike during the investigation, but there was potential to decrease susceptibility by decreasing breech cover and breech wrinkles in this flock.

}, issn = {1176-5283}, author = {Scobie DR and Hickey SM and Maslen DP and Black GM} } @conference {75886, title = {An update on genetic parameters for facial eczema susceptibility in New Zealand dairy cattle}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {117-121}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {Resistance/tolerance to facial eczema (FE) is a heritable trait in New Zealand dairy cattle, as measured by genetic variation in liver enzyme levels. AgResearch has been collecting data from herds clinically affected by FE, by blood-sampling all cows in these herds, as a low cost method of phenotyping large numbers of animals. Over the past seven autumns, 66 herds and 14,799 cows were sampled. Breeding values for FE resistance were calculated for 238 sires. One complicating factor was the level of FE-protection provided by zinc sulphate administered through the farm water supply. Variable levels of serum zinc in cows were found, due to factors including water intakes and weather conditions. In zinc-treated herds there were three classes of cows: those still affected by FE, and others seemingly FE-tolerant either through genetics or having enough circulating zinc to provide protection. The zinc status of each herd was recorded at the time of blood sampling after a clinical outbreak. Data were analysed within zinc-treated and not zinc-treated herds to provide genetic parameters for each. Heritabilities in herds according to zinc status were very similar, regardless of zinc status.}, issn = {1176-5283}, author = {Cullen NG and Morris CA and Hickey SM and Henderson HV} } @conference {69517, title = {Daily water intake by individual cows on a pasture diet during mid lactation}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {257-260}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {Three small studies were undertaken in the Waikato involving daily measurements of water intake of individual mixed-age Holstein-Friesian and crossbred cows, mid lactation. In Trial 1 at Ruakura, cows were monitored whilst grazing and, in Trials 2 and 3 at DairyNZ, pasture was cut and fed to cows indoors. Mean daily water intakes by Trial were 41.3, 78.2 and 60.1 L/cow, respectively; standard deviations were 4.5, 8.3 and 7.2 L/cow, and between-cow repeatabilities averaged 0.56 {\textpm} 0.08. There were two days of rain in Trial 1; the greater of these rainfalls (26.4 mm) led to a 62\% reduction in water intake. There was no rainfall above 2 mm in Trials 2 or 3. Daily feed intakes (and feed dry-matter percentages) of cows were also available (Trials 2 and 3), and combined daily water intake (calculated from actual-water intakes plus water content of the feed consumed) averaged 104.5 and 110.6 L/cow, respectively. At an average water intake from the trough of 60 L/cow, the 25\% of cows drinking least are expected to drink ~8.4 L (14\%) less than average. This knowledge is useful when planning management practices such as supplementing water with zinc sulphate for facial eczema protection.}, issn = {1176-5283}, author = {Morris CA and Hickey SM and Thom ER and Waugh CD} } @conference {69497, title = {Genetic and environmental relationships between liveweight change over the summer in Perendale ewes and the lifetime live weight profiles of their progeny}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {165-170}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {Multi-generation data from 1985 to 2002 were analysed from a 200-ewe Perendale flock to investigate genetic and environmental relationships between ewe pre-mating liveweight change and live weight of their progeny at birth, weaning, and 1, 2, 3, 4 and 5 years of age. The flock was managed at Whatawhata Research Centre and then at Winchmore Research Station, with selection for either increased or decreased wool bulk at one year of age. A total of 162 rams were used in a single-sire system. Numbers of resulting dam-offspring pairs ranged from 3,510 for progeny birth weights, to 369 for daughter 5-year-old live weights. Genetic and environmental correlations of progeny trait on dam trait, and the derived genetic (bG) and environmental (bE) regressions, were obtained from a restricted maximum likelihood animal model with a relationship matrix, after adjustment for known fixed effects. The bG estimates were all non-significant, with 14 of the 20 estimates tending to be negative. Three of the 20 estimates of bE were significant, with values ranging from 0.7 to 1.3\% of mean progeny weight per kg dam gain. The estimated environmental relationships were of insufficient magnitude to impact on the flock{\textquoteright}s productivity in the short term.}, issn = {1176-5283}, author = {Sumner RMW and Morris CA and Hickey SM and Sheppard AM} } @conference {69467, title = {Natural variation in levels of Immunoglobulin A in bovine milk}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {43-45}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {Bovine milk has been reported to contain low levels of Immunoglobulin A (IgA) in comparison to human milk (0.1 g/L vs 1.0 g/L, respectively) (Butler, 1999). However, analysis of milk collected from cows vaccinated to induce antigen-specific IgA secretion in milk (Hodgkinson, et al., 2007) has demonstrated that the IgA response of individual cows is variable, with a ~10-fold range in the IgA production by individual vaccinated cows at peak lactation (E.A. Carpenter, Unpublished data). Approximately 10\% of these cows are classified as {\textquotedblleft}high milk IgA producers{\textquotedblright}, defined by Wagter et al.(2000) as those cows with a milk IgA concentration greater than one standard deviation above the group mean.}, issn = {1176-5283}, author = {Carpenter EA and Hurford DR and Hickey SM and Morris CA} } @conference {60957, title = {Relationship between blood phylloerythrin concentration and gamma-glutamyltransferase activity in facial eczema-affected cattle and sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {69}, year = {2009}, month = {Jun}, pages = {118-122}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Phylloerythrin (PLE) is a photo-dynamic compound, a natural breakdown product of chlorophyll. Its concentration and relationship with gamma-glutamyltransferase (GGT) were determined in animals seriously affected with facial eczema (FE). Seven commercial cattle herds (n = 1,455) and one experimental sheep flock (n = 597), each containing clinically affected animals, were monitored. On a pooled within-farm basis, mean PLE concentration was significantly higher in clinical FE cases than in non-clinical animals in cattle (28.7 vs 16.0 relative units, P <0.001), and in lambs (0.282 vs 0.024 {\textmu}g/ml, respectively, P <0.001). PLE concentration rose in some, but not all, animals when GGT activity exceeded \~{}600 IU/L in cattle and \~{}400 IU/L in lambs (Reference GGT range in normal (unchallenged) animals: 0 to 40 IU/L, cattle; 32 to 70 IU/L, sheep). A heritability for PLE concentration was estimated in cattle (0.19 {\textpm} 0.07), and phenotypic and genetic correlations with LogeGGT were 0.37 {\textpm} 0.02 and 0.92 {\textpm} 0.09, respectively. In the lambs the phenotypic correlation between LogeGGT and PLE was 0.32 {\textpm} 0.04. Thus PLE is a partially inherited trait, and is associated with visible signs of FE, especially above GGT thresholds of \~{}600 IU/L in cattle and \~{}400 IU/L in lambs. }, issn = {1176-5283}, author = {Morris CA and Hickey SM and Phua SH} } @conference {41917, title = {Genetic parameters for resistance to facial eczema in dairy cattle}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {66}, year = {2006}, month = {Jan}, pages = {310-314}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Napier}, abstract = {A project was designed to progeny-test dairy industry sires for their resistance to facial eczema (FE), as a preliminary step towards identifying DNA markers or genes for FE resistance. The FE disease is caused by the toxin, sporidesmin, produced by spores of a fungus, Pithomyces chartarum, found on many pastures in summer and autumn in the North Island of New Zealand. In susceptible animals, sporidesmin causes liver injury, and the cost of FE to the dairy industry is measured in tens of millions of dollars in years with serious outbreaks ($3.6 to 66.2M per annum). Earlier studies in New Zealand have established that resistance to FE in cattle is a heritable trait, with resistance measured by variation in activity in blood of liver-derived enzymes, gamma-glutamyltransferase (GGT) and the associated glutamate dehydrogenase (GDH). Widely used Friesian and Jersey sires were progeny-tested via 572 specially-reared sons (born in 2002-04 and dosed with sporidesmin), and also via 3761 daughters in autumns 2004 and 2005 in 17 herds with 3-22\% clinical cases of FE per herd. The data were combined from all sources, including four earlier years of GGT records (1173 animals born in the 1986, 1989, 1990 and 1992 birth years), and standardisation was applied to each contemporary group. Heritabilities were estimated for Friesians (0.47 {\textpm} 0.07 for log GGT; 0.32 {\textpm} 0.08 for log GDH) and for Jerseys (0.37 {\textpm} 0.06 and 0.39 {\textpm} 0.09, respectively), and there was a very high genetic correlation between activities of the two enzymes (0.93 {\textpm} 0.03). Sixty-eight sires had reliabilities of >0.70 for log GGT Breeding Value and 71 others had reliabilities between 0.60 and 0.70. The sires progeny-tested in this way generally were already proven for dairy traits and had been widely used, so that FE selection among these sires would be an additional trait when they were already old. Alternative approaches would be to performance-test young bulls for FE resistance, or to use sire and progeny data and their DNA to identify DNA markers or genes for FE resistance. }, issn = {1176-5283}, author = {Cullen NG and Morris CA and Hickey SM} } @conference {41832, title = {Further testing of the effect of a calpain-1 variant on meat tenderness in cattle}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {65}, year = {2005}, month = {Jan}, pages = {266-270}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {We have previously reported that a single-nucleotide polymorphism (SNP) on the large subunit of micro-calpain (the calcium-activated neutral protease-1 gene) is associated with differences in tenderness, as measured in cooked steaks from the longissimus dorsi of animals from the AgResearch Jersey-Limousin Beef DNA-marker trial. The effect was significant at the intermediate stages of the tenderising process and had little effect on initial or ultimate tenderness, so that tenderising was accelerated in animals having one or two copies of the favourable variant. We have now analysed tenderness and genotype data from 310 additional animals, comprising Hereford-cross and pure Angus breeds slaughtered under varying conditions of electrical stimulation and aged at a range of temperatures. Results in all cases support the original finding: animals with two copies of the {\textquoteleft}C{\textquoteleft} allele (the SNP on Exon-9 encoding alanine at amino acid number 316) have more tender meat (decreased shear force) at the intermediate stages than animals with two copies of the {\textquoteleft}G{\textquoteleft} allele (encoding glycine). Combining measurements from three intermediate cook times, mean shear forces from {\textquoteleft}CG{\textquoteleft} were less than from {\textquoteleft}GG{\textquoteleft} genotypes by 0.80 {\textpm} 0.29 kg (P < 0.01), and mean shear forces from {\textquoteleft}CC{\textquoteleft} were less than from {\textquoteleft}CG{\textquoteleft} genotypes by 1.19 {\textpm} 0.36 kg (P < 0.001). These results show that a genotype substitution from {\textquoteleft}GG{\textquoteleft} to {\textquoteleft}CC{\textquoteleft} is associated with a difference in shear force in longissimus dorsi steaks of approximately 20\% at intermediate aging times. KEYWORDS: cattle; meat; tenderness; micro-calpain; SNP. }, issn = {1176-5283}, author = {Cullen NG and Morris CA and Veenvliet BA and Hickey SM and Dobbie PM and Wilson T} } @conference {41837, title = {Repeatability of fatty acid composition in pm:am milk samples from cows}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {65}, year = {2005}, month = {Jan}, pages = {297-299}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {The present study was designed to estimate the repeatability of fatty acid composition in cows{\textquoteright} milk collected at a pm:am herd test. As part of a larger project, whole milk was collected during a routine herd test in March 2003 from 10 Friesian and 10 Jersey cows at Flock House, in the evening and again the following morning. Fat in the 40 samples was separated by centrifugation, fatty acids were converted to their methyl esters, and individual fatty acid percentages in each sample were assayed by gas chromatography. In general, the fatty acid composition of milk was very similar at the pm and am samplings. For the fatty acids making the largest contributions (10 to 29\% of the total) to fatty acids present in milk (C14:0, C16:0, C18:0 and C18:1 cis-9 (oleic)) and for conjugated linoleic acid and the Mono- Unsaturated/Saturated ratio, pooled within-breed correlations of compositions between pm and am milk samples were high (0.76, 0.80, 0.88, 0.76, 0.75 and 0.74, respectively; standard errors 0.06 to 0.12). The pm:am correlation, averaged over the most abundant 15 fatty acids in milk, was 0.77 {\textpm} 0.10. It is concluded that a single milk sample or a pooled pm:am sample is adequate for estimating the composition of the predominant fatty acids. KEYWORDS: milk; fatty acid; cows; repeatability. }, issn = {1176-5283}, author = {Morris CA and Hickey SM and Agnew MP} } @conference {41485, title = {Heritability of puberty traits in dairy heifers in commercial herds}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {64}, year = {2004}, month = {Jan}, pages = {115-117}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {Age and weight at puberty (first behavioural oestrus) are known to be heritable traits in experimental beef and dairy cattle. The recording required is usually labour-intensive, and may also be expensive if serial blood samples are taken to estimate progesterone concentrations. Our objective in this study was to ascertain whether a less labour- intensive approach for estimating age at puberty (AP) would still provide enough statistical power to show genetic variation among sire groups of Friesian and Jersey heifers grazing in large groups. Commercial heifers (n = 797) were born in the late winter/early spring of 2002, and were predominantly the result of artificial insemination (AI) matings. They were reared to weaning in six herds, and then grazed in five herds through 2003. Tailpaint was applied to heifers at visits to the grazing herds at 4-6 week intervals, and tailpaint loss was recorded at each visit to determine approximate date at puberty. Birth dates were known, and hence AP was calculated. The heritability of yearling live weight (W12) was used as a control measure. From four of the herds (n = 453), there were animals by 13 widely-used AI sires (9 Friesian and 4 Jersey), and 10 other sire groups were represented with at least 5 daughters each. The phenotypic standard deviations for AP and WP were 48 days and 34 kg, similar to that found in New Zealand experimental beef cattle herds. The pooled within-breed heritability estimates for AP, WP and W12 were 0.09 {\textpm} 0.10, 0.21 {\textpm} 0.14 and 0.24 {\textpm} 0.15, respectively. Confounding of AI sire group with date of birth of heifer was encountered. The breeding-value difference in AP between the top 7 and bottom 6 of the widely used AI sires was 15 days, or 1.05 genetic standard deviations. In conclusion, recording AI calves in large grazing herds may be a practical method of getting access to puberty data, but more frequent visits to each herd would probably be needed to reduce the noise, and increase the heritability for AP and WP. }, issn = {1176-5283}, author = {Morris CA and Hickey SM} } @conference {41434, title = {Heritability of Johne{\textquoteright}s disease and survival data from Romney and Merino sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {63}, year = {2003}, month = {Jan}, pages = {179-182}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Queenstown}, abstract = {Eight years of health records for ovine Johne{\textquoteright}s disease (OJD) from a long-term breeding trial with Romneys and Merinos at AgResearch{\textquoteleft}s Tokanui Station were analysed, to study the quantitative genetics of animal resistance/susceptibility to OJD. Necropsy records were used in preference to serology to determine OJD status. A total of 2348 Romney and 1297 {\textquoteleft}Merino{\textquoteleft} ewe records (5 groups: two purebred Merino groups (Australian imported superfine and NZ purebred Merino), two Merino x Romney halfbred groups and a superfine Merino back-cross) were analysed for OJD and survival, comprising animals born between 1971 and 1978. Few males were retained past two years of age, so disease and survival data on males were excluded. Romney ewes had a mean lifetime incidence of OJD of 3.49\% (range, by year of birth, 2.11 to 5.00\%), whilst the mean for Merino ewes was 4.78\% (range, by year of birth, 0.0 to 7.74\%). The breed contrast approached significance (P<0.051). The mean age at OJD incidence was 3.44 {\textpm} 0.09 years for Romneys, compared with a mean age for surviving females in the sample of 5.04 {\textpm} 0.02 years (P<0.001). Corresponding means for Merinos were 3.38 {\textpm} 0.13 and 5.00 {\textpm} 0.04 years, respectively (P<0.001). The heritability of lifetime incidence of OJD, considered as a binomial trait and using animal-model restricted maximum likelihood methods, was estimated as 0.07 {\textpm} 0.14 and 0.18 {\textpm} 0.11 for Romneys and Merinos respectively, giving an overall value (pooled within breeds) of 0.14 {\textpm} 0.09. Adjusting for Merino group in the relationship matrix (rather than as a fixed effect) led to a heritability for Merinos of 0.24 {\textpm} 0.09. These estimates may be biased upwards by {\textquoteleft}vertical transmission{\textquoteleft} of OJD organisms from dam to offspring. The heritability of age at death/culling had values of 0.11 {\textpm} 0.04 and 0.16 {\textpm} 0.05 for Romneys and Merinos respectively, with a pooled value of 0.13 {\textpm} 0.03. With the low heritability estimates for OJD in Romneys it is concluded that traditional breeding methods to reduce the incidence would be slow or unsuccessful; however, for Merinos, selection could begin to reduce the incidence, but ranking later generations may become difficult. }, issn = {1176-5283}, author = {Hickey SM and Morris CA and Dobbie JL and Lake DE} } @conference {41404, title = {A single-nucleotide polymorphism on Calpain-1 is associated with meat tenderness in cattle}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {63}, year = {2003}, month = {Jan}, pages = {53-56}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Queenstown}, abstract = {Variability in tenderness remains a major concern to the meat industry, and our objective was to identify genetic effects on beef meat tenderness, in animals treated alike, and under similar post-mortem processing conditions. A quantitative trait locus (QTL) for beef tenderness has been located on the same region of chromosome 29 in a United States Department of Agriculture (USDA) study and in our research. Micro-calpain, or calcium-activated neutral protease (CAPN1), has been identified as a candidate gene. The calpain/calpastatin system is involved in the change of tenderness with time, by regulating post-mortem proteolysis. The CAPN1 gene was sequenced by USDA workers who identified single-nucleotide polymorphisms (SNPs) in two exons. These results were followed up as part of the AgResearch Jersey-Limousin Beef QTL trial, where steak samples were obtained from the longissimus dorsi of 416 animals slaughtered at about two years of age. The segregating USDA and NZ families were both heterozygous for one of these SNPs, on exon 9, and this region was predicted to alter the protein sequence by the substitution of alanine for glycine in Domain II. Both families were genotyped for these two SNPs, as well as for six intronic polymorphisms, to define haplotypes. Analysis of tenderness measurements in the NZ data (n=81 animals) showed a difference between paternal CAPN1 haplotypes, with the SNP encoding alanine at amino acid number 316 being associated with more tender meat (decreased shear force) relative to the SNP encoding glycine (P<0.00001). The association of the maternal haplotypes with meat tenderness phenotypes (P<0.01) was also consistent with the hypothesis of CAPN1 as the gene underlying the QTL effect. The sire and dam effects together accounted for over 30\% of the residual variance in tenderness. Our results show that a single SNP test in the laboratory can distinguish genetically tender and genetically tough animals at any age. }, issn = {1176-5283}, author = {Cullen NG and Page BT and Morris CA and Hickey SM and Dobbie PM} } @conference {41261, title = {Correlations among beef carcass composition and meat quality traits from a genetic marker trial}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {61}, year = {2001}, month = {Jan}, pages = {96-99}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {A collaborative beef cattle project between AgResearch and Adelaide University is described, which had the aim of identifying genetic markers (DNA markers) for carcass composition and meat quality traits. Two extreme breeds were used, the Jersey and Limousin, and first-cross Jersey x Limousin bulls were mated to cows of both breeds to produce experimental animals in two herds, in New Zealand and Australia. The present paper provides information on relationships among some traits recorded in the New Zealand herd, with a total of 416 back-cross cattle of both sexes slaughtered as 2-year-olds at Ruakura in the springs of 1998 and 1999. The recorded data included hot carcass weight and the butcher-dissected weights of meat, fat and bone in the right side, expressed as percentages of side weight (MP, FP and BP respectively). The pH decline in the right striploin, removed from the carcass after dressing and maintained at a constant 15{\textdegree}C, was monitored to derive the initial (pH1), ultimate (pHu), and the rate of fall of pH. Average shear force (SAVG) and the half-life of the ageing rate (SHLF) were measured in striploin steaks cooked immediately after rigor and then at intervals until ultimate tenderness. Percentage weight loss (PWL) during cooking was recorded. Also measured in the striploin were the concentrations of three metabolic enzymes, lactate dehydrogenase (LDH), isocitrate dehydrogenase (ICDH) and 3-hydroxyacyl-Coenzyme A dehydrogenase (HAD), and the proteolytic enzymes m- and milli-calpain, and their inhibitor calpastatin (CAST). Glycogen concentration in the muscle at slaughter, expressed as the glycolytic potential (GLYP), was estimated from the sum of the concentrations at rigor of glucose, glucose-6-phosphate, lactate and residual glycogen. The range of pHu values was small, probably because all animals were regularly handled. Correlations, after adjustment for breed group, sire and slaughter group, included: MP with FP, -0.82; PWL with MP, 0.20; PWL with FP, -0.29; MP with enzymes LDH, ICDH and HAD, 0.22, -0.21, -0.03; FP with ICDH, 0.16; SAVG with SHLF, 0.48; SHLF with CAST, m-and milli-calpain, 0.28, -0.14, 0.03; CAST with m- and milli-calpain, 0.26, 0.38; GLYP with pH1 and pHu -0.01 and -0.17. Overall, HCW, MW and composition traits were not correlated with pH traits or SAVG, or m- or milli-calpain concentrations; HCW and MW were positively correlated with LDH and GLYP. }, issn = {1176-5283}, author = {Morris CA and Daly CC and Cullen NG and Hickey SM} } @conference {41198, title = {Genetic parameters for improvement of dual-purpose flock productivity with constraints on mature ewe body weight}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {203-206}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {SIL provides opportunity for inclusion of information on mature ewe body weight in animal evaluations. This paper reports estimates of the parameters needed for these evaluations. Traits analysed were: weaning weight (WWT) and hogget liveweight in May (ALW); hogget yearling liveweight (HLW) and greasy fleece weight (HFW); and pre-mating body weights (ELW), number of lambs born (NLB) and greasy fleece weights of ewes at 2 to 5 years of age. EFW and especially ELW, were highly repeatable (>0.9), the pattern of genetic correlations suggesting that breeding ewes had reached maturity in these traits by 40 months of age. Direct and maternal genetic effects on WWT showed similar heritabilities (0.14{\textpm}0.02 \& 0.18{\textpm}0.02) and were positively correlated (0.20{\textpm}0.08). Maternal influences on traits measured at old ages were much reduced, direct heritabilities being similar to published estimates. WWT showed a high direct genetic correlation with LW8 and HLW (0.82{\textpm}0.02), but lower with ELW (0.70{\textpm}0.06 for 3-year old ewes). LW8 and HLW showed even higher direct genetic correlations with ELW (of the order of 0.90{\textpm}0.02). EFW was highly correlated genetically with HFW (0.80{\textpm}0.03), HLW (0.25{\textpm}0.04), ELW (0.23{\textpm}0.05) and LW8 (0.21{\textpm}0.04). Dual-purpose genetic response predictions were derived using SIL{\textquoteright}s recently revised relative economic values for a dual-purpose index. Its correlation with aggregate breeding value was 0.67. It predicted positive selection responses (per generation and standard deviation of selection pressure) in all traits: LW8 (2.1 kg), EFW (0.14 kg), NLB (0.038 lambs/ewe) and ELW (2.4 kg or 87\% of the predicted single trait response despite the negative economic weight for this trait). Restraining the response in ELW to zero required a ten-fold increase in the negative relative economic value for this trait, and reduced the correlation of the index with aggregate breeding merit to 58\% of its previous value. Such restriction greatly increased the relative contribution of fleece weight to economic response, made little difference to the contribution of NLB (although the absolute rate of progress was nearly halved), and reduced the contribution of growth; maternal effects on weaning weight became relatively more important. }, issn = {1176-5283}, author = {Clarke JN and Dobbie JL and Jones KR and Wrigglesworth AL and Hickey SM} } @conference {41096, title = {Genetic progress in a Romney Group Breeding Scheme}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {59}, year = {1999}, month = {Jan}, pages = {117-120}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The Auckland Romney Development Group was established in 1968 and its aims continue to be to test and select rams for Group Members, and to breed rams for sale under conditions relevant to farming in the greater Auckland district. Breeding objectives include increased litter size (NLB), weaning weight (WWT), yearling live weight (YLW), yearling greasy fleece weight (YFW), and also increased facial eczema (FE) tolerance. Each year until 1993, members received selected nucleus-bred 15-month rams for use at home, and the next cut of nucleus rams and some elite homebred rams were offered as breeding stock for sale. From 1993, restricted maximum likelihood methods were introduced to calculate breeding values, and across-age ram selection was applied. At the same time, the nucleus ewes were re-distributed across all Members{\textquoteleft} flocks, and between-flock and between-year genetic links were maintained by movement of sires for mating. Estimates of total genetic progress by birth-year (obtaining data from Animalplan files, which were only available from 1986) were: WWT (1986-97) 1.83{\textpm}0.17 kg (7.8\% of the mean), YLW 2.76{\textpm}0.24 kg (6.4\%), YFW 0.23{\textpm}0.01 kg (7.3\%) and NLB (1986-95) 0.029{\textpm}0.015 lambs (1.8\%), and all flocks have contributed to the long-term genetic changes. Annual genetic trends over the period were approximately linear, except for YLW which appeared to show an increasing response rate. This is probably related to the extensive progeny testing carried out since 1994 to study sire families which appear to be elite for YLW, using progeny-test matings of rams to outside tester ewes. Segregation tests for a possible major gene have been carried out. Some evidence of bimodal distributions for YLW within sire was found, with a gene whose effect was +9\% of the mean, in heterozygotes. Since 1993, secondary selection decisions based on FE have been complicated by across-flock selection, but genetic progress for this trait appears to be linear, with a heritability estimate for log (gamma glutamyltransferase; GGT) of 0.34{\textpm}0.09. Over the birth years 1981-1997 there was genetic change in GGT by a factor of 0.71 (29\% improvement), compared with a factor of 0.30 (70\% improvement) over the same time period in the single-trait FE selection lines at Ruakura (Resistant versus Control lines). }, issn = {1176-5283}, author = {Morris CA and Amyes NC and Hickey SM} } @conference {41063, title = {Sex and age effects on genetic parameters for wool production and qualities}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {59}, year = {1999}, month = {Jan}, pages = {23-26}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Heritabilities and genetic correlations were estimated for New Zealand Romney sheep from within the selected and control lines of a 25-year selection experiment for greasy hogget fleece weight and yearling body weight. Average repeatability of clean fleece weight in 1 to 5 year-old ewes was 0.56, 25\% higher than the average heritability of 0.44. The average genetic correlation among measurements at different ages was 0.89. Sexual dichotomy in the relative predictive power of hogget records was most apparent for greasy and clean fleece weights but was evident to some degree for bulk and brightness as well, due mainly to lower heritabilities in male compared to female hoggets. Average co-heritability of greasy hogget with adult clean fleece weights was 25\% lower for male (0.26) compared to female (0.35) hoggets, in this case due to a lower genetic correlation (0.69 vs 0.81) as well as a lower heritability (0.33 vs 0.43, respectively). A repeatability model seemed an adequate approximation for estimation of breeding merit for most wool quality traits studied but not for lifetime wool production. }, issn = {1176-5283}, author = {Clarke JN and Dobbie JL and Jones KR and Wrigglesworth AL and Hickey SM} } @conference {40732, title = {Genetic parameters of lifetime wool production}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {55}, year = {1995}, month = {Jan}, pages = {268-271}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Heritabilities and genetic correlations were estimated from the selected and control lines of a 25-year selection experiment for hogget greasy fleece weight (GFW). The heritability of GFW was higher in the selected than the control line and in female hoggets (0.48) compared with males (0.32). Inter- age genetic correlations were less than unity, and higher in fleece weight selected animals. Average genetic correlations between hogget and adult records were higher in ewe than ram hoggets. Together these parameters gave co-heritability estimates (pooled across lines) for greasy hogget with clean adult ewe fleece weights of nearly half the average magnitude in males (0.21) compared with female (0.36). These results have important repercussions to the design of effective selection strategies for improvement of lifetime wool production. }, issn = {1176-5283}, author = {Clarke JN and Dobbie JL and Hickey SM and Jones KR and Wrigglesworth AL} } @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 {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 {40117, title = {Follicle and fleece characteristics of Merinos, Romneys and Merino-Romney crossbreds}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {48}, year = {1988}, month = {Jan}, pages = {195-200}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {In the first of 2 experiments, the milk production, food conversion efficiency, and grazing uniformity of Friesians and Jerseys were compared during a grazing trial of 21 d duration in mid lactation. Four groups of each breed, consisting of 12 cows per group, were offered pasture allowances of 10, 20, 30 or 40 kg dry matter (DM)/cow/d. In experiment 2, the energy metabolism of 6 Jerseys and 6 Friesians was compared by means of open circuit calorimetry. Energy balances were established for each cow when offered pasture at ad libitum, and at 75\% National Research Council (NRC) requirements. In Experiment 1, on average Friesians produced 26\% more milk, 6\% more milkfat, 13\% more protein and 24\% more lactose. At the lowest level of feeding (10 kg DM allowance/cow/d) Friesians produced more milk but less milkfat and protein than the Jerseys. Friesians consumed more pasture dry matter (av 13\%), lost more live weight and had a lower food conversion efficiency (61 v 67 g milkfat/kg DM consumed) than the Jerseys. It was calculated that milkfat per ha, at a common live weight was lower for the Friesians than Jerseys particularly at high rates of stocking. Partitioning of gross energy into digestible energy or metabolisable energy was not significantly affected by breed in Experiment 2, but the efficiency of utilisation of metabolisable energy for milk and tissue (balance energy) was higher for Jerseys than Friesians (0.58 v 0.48 respectively). The results suggest that in mid lactation Friesians produce more milk and milk solids per cow than do Jerseys because of the greater feed intake of Friesians. In contrast, the higher food conversion efficiency, utilisation of metabolisable energy and dry matter consumption per unit live weight of Jerseys allows them to achieve a higher production per hectare than the Friesians. Comparisons between breeds at other stages of lactation is warranted, particularly in light of current discussions about the system of payment for milk.}, issn = {1176-5283}, author = {Meikle HE and Wickham GA and Rae AL and Dobbie JL and Hickey SM} } @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 {39784, title = {A comparison of the composition and carcass quality of Kelly and Russian castrate, ram, wether and ewe lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {42}, year = {1982}, month = {Jan}, pages = {117-118}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Data on M. longissimus dorsi (LD) area, width and depth were examined on 1957 lamb carcasses graded for export as either P (moderate to heavy fat cover) or Y (light fat cover) over 3 slaughter seasons. Lambs were sired by 1 of 11 different breeds mated to Romney ewes. Carcasses in the 2 grades differed in mean weight and LD measurements in the different seasons. After adjustment for differences in carcass weight and the effect of sire breed, LD area did not differ between the P and the Y grades. After adjusting the A (width) and B (depth) measurements of differences in carcass weight and sire breed, P grade LD{\textquoteright}s were significantly narrower and deeper than those from the Y grade, but the differences were small (maximum of 5\% for depth in 1970/1 season) and of little practical significance. Thus if the leaner Y grade carcasses are desired, and this is done on a within breed basis, the LD area or shape should not be adversely affected provided carcass weights are not reduced.}, issn = {1176-5283}, author = {Kirton AH and Clarke JN and Hickey SM} } @conference {39790, title = {Evaluation of dam breeds and crosses for export lamb production}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {42}, year = {1982}, month = {Jan}, pages = {133-136}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The effects of castrating and surgically dehorning male Drysdale and Tukidale lambs at birth or docking on subsequent horn growth were investigated in 3 lamb crops at Whatawhata Hill Country Research Station. Castration was more effective than dehorning in reducing subsequent horn growth. A combination of castration at birth and dehorning at docking was the most effective way to treat lambs to reduce horn growth. Excision of germative tissue around the base of the horn following dehorning increased the effectiveness of dehorning. Attainment of meat inspection standards for horned breeds is more dependent on the "trimmers" on the slaughter chain than the time of dehorning.}, issn = {1176-5283}, author = {Clarke JN and Atkins KD and Geenty KG and Johnson DL and Hickey SM and Wilson JA} }