@conference {3672, title = {Using genomic information to predict sex in dairy cattle}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {26-30}, address = {Adelaide}, abstract = {Sex misassignment of animals in breeding programmes can arise from sources such as misidentification and data-entry errors. The objective of this study was to develop a test for checking sex using Single Nucleotide Polymorphism (SNP) chip genotypes on chromosome X. All animals in this study were genotyped using the GeneSeek Genomic Profiler LD v3 (GGPv3) SNP chip. After filtering, 16478 sex-verified animals (15703 cows and 775 bulls) were available in the training set. The proportion of heterozygous SNPs on chromosome X was used to predict sex. The distribution of heterozygosity was bimodal in the training population with a clear gap between 0.01 and 0.03. Using the heterozygosity cutoff of 0.02 resulted in 100\% and 99.6\% prediction accuracy for males and females, respectively. Additional analysis determined that four incorrectly classified females were either XO or inbred. The test was validated on an independent set of 2212 animals, which resulted in seven animals for which the predicted sex differed to the recorded sex. Physical examination of these animals revealed that the predicted sex was correct in all cases. The method developed is a useful addition to quality control of genotypes obtained as part of a genomic selection programme.}, issn = {1176-5283}, author = {Zhang IL and Couldrey C and Sherlock RG} } @conference {42045, title = {Liveweight and body condition of single- and twin-bearing Merino ewes}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {68}, year = {2008}, month = {Jan}, pages = {67-68}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Brisbane, Australia}, abstract = {

While dairy cows are generally milked twice-a-day (TAD) in New Zealand, more farmers are adopting a once-a-day (OAD) milking routine to improve their lifestyle, reduce farm costs and improve animal welfare. Clark et al. (2006) reported that the yield of milksolids (MS) from Jersey cows was less affected (-19.9\%/cow) by OAD milking than the MS yield from Holstein-Friesian cows (-29.4\%/cow). Jersey cows milked OAD in Taranaki between 2000 and 2004 averaged 222 kg MS/cow and 979 kg MS/ha (Clark et al., 2006). In the 2006/07 season ...Continued

}, issn = {1176-5283}, author = {van Reenen EH and Kenyon PR and Sherlock RG and Hickson RE and Morris ST} } @conference {41561, title = {The effect of sward height during pregnancy on the wool follicle and fibre characteristics of twin and triplet born lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {65}, year = {2005}, month = {Jan}, pages = {168-172}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Previous work estimating the impact of differential feeding of ewes during pregnancy, on lamb wool follicle development, has been done primarily with single- and twin-bearing ewes. The aim of this study was to compare the follicle development and fibre characteristics of twin- or triplet-born/reared lambs, born to ewes offered different sward height allowances during pregnancy and lactation. After pregnancy scanning, 186 twin- and triplet-bearing Romney ewes with 6 weeks wool growth, were randomly allocated to four different sward heights (2, 4, 6 and 8 cm). Within the first 24 hours of parturition ewes were transferred to one of two sward heights (4 and 8 cm). The wool and follicle characteristics of twin- (n = 65) and triplet-born (n = 63) ewe lambs were compared. Fleeces from triplet-born lambs were lighter (1.59 kg vs 1.82 kg, P < 0.05) and finer (32.7 μm vs 33.4 μm, P < 0.05) than those from their twin-born counterparts. Lambs born to ewes offered higher sward heights during pregnancy had increased loose wool bulk (P < 0.01). Although increasing sward height during pregnancy increased fibre diameter in twin-born lambs, there was no similar relationship for triplet-born lambs (P < 0.05). Sward height during pregnancy had no effect on secondary follicle number in twin-born lambs but, triplet-born lambs born to ewes grazed on the 4 cm sward tended to have significantly higher numbers of secondary follicles than those grazed on 6 cm (89.2 vs 66.0, P < 0.05). More work is necessary to determine whether this interaction has practical implications for breeding replacements. Nutritional treatments during lactation had no significant effects on lamb wool characteristics. KEYWORDS: feeding; nutrition; follicle development; wool bulk; wool characteristics. }, issn = {1176-5283}, author = {Sherlock RG and Kenyon PR and Morris ST} } @conference {41519, title = {Are elevated maternal thyroid hormone concentrations after-mid-pregnancy shearing responsible for changes in lamb fleece characteristics?}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {64}, year = {2004}, month = {Jan}, pages = {272-276}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {This study was designed to test the hypothesis that elevated maternal thyroid hormone concentrations in mid- pregnancy are responsible for the observed differences in lamb follicle characteristics as a result of mid-pregnancy shearing. The study involved 51 twin-born lambs in a 2 x 2 factorial design involving dams that were either shorn or unshorn in mid pregnancy and had either normal or elevated thyroid hormone levels. All ewe groups were thyroidectomised except for unshorn-normal ewes which were sham-operated. The thyroxine implant and injection regimes used to manipulate maternal thyroid hormone levels in mid-pregnancy were successful in mimicking the levels previously reported in mid-pregnancy shorn ewes. Lambs born to shorn dams had significantly (P<0.05) higher coefficients of variation of mean fibre diameter. Dam shearing treatment had no effect on any other follicle or wool characteristic. Lambs born to ewes with elevated thyroid levels in mid-pregnancy had a significantly (P<0.05) higher numbers of secondary fibres, and tended to have more primary fibres (P=0.08) and whiter wool (P=0.06). The absence of any dam shearing-treatment effect on secondary and primary fibre numbers, fibre diameter and length, suggests that the changes observed in follicles and wool characteristics of lambs born to mid-pregnancy shorn dams are primarily due to elevations in maternal thyroid hormone levels in mid-pregnancy. More work is required to confirm this hypothesis. }, issn = {1176-5283}, author = {Kenyon PR and Sherlock RG and Morris ST} } @conference {41498, title = {The effect of sward height during pregnancy on wool grown by ewes rearing twins or triplets}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {64}, year = {2004}, month = {Jan}, pages = {171-174}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {Previous work estimating the impact of rearing lambs on wool growth and processing characteristics has been done primarily with single and twin-bearing ewes. The effect of bearing/rearing triplets on wool growth has been largely extrapolated from these data. The aim of this study was to compare the wool growth and quality of twin- and triplet- bearing/rearing ewes offered different sward height allowances. After pregnancy scanning, 94 Romney ewes (including 68 twin- and 26 triplet-bearing ewes) with 6 weeks wool growth, were randomly allocated to four different sward heights (2, 4, 6 and 8 cm). Within the first 24 hours of parturition ewes were transferred to one of two sward heights (4 and 8 cm). Ewes were shorn 87 days after parturition, the fleece was weighed and a sample was taken from the midside for measurement of fleece characteristics. There were no interactions between nutritional treatment and litter size for any wool measurements. Fleeces from twin-bearing/rearing ewes tended to be heavier (P<0.1 ; 2.0 kg vs 1.9 kg) than those from triplet-bearing/rearing ewes. There was no effect of litter size on any other wool characteristic. Ewes offered 2 cm during the last half of pregnancy had lighter (1.6 vs 2.2 kg, P<0.05) and finer (39.0 vs 41.8 {\textmu}m, P<0.05) fleeces than those offered 4 cm but there was no increase in weight or fineness for those offered more than 4 cm. Nutritional treatments post parturition had no significant effects on wool characteristics. There seems to be little benefit, in terms of wool growth and wool processing characteristics, of offering twin- or triplet-bearing ewes a sward height of more than 4 cm. }, issn = {1176-5283}, author = {Sherlock RG and Torbatinejad N and Kenyon PR and Morris ST} } @conference {41425, title = {Metabolic changes in ewes shorn during mid-pregnancy}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {63}, year = {2003}, month = {Jan}, pages = {144-148}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Queenstown}, abstract = {Previous work has shown that, under appropriate circumstances, mid-pregnancy shearing results in an increase of both the birth and weaning weights of multiple-born lambs. However, the physiological mechanisms for this response are poorly understood. This paper attempts to clarify the link between mid-pregnancy shearing and heavier lamb weights by investigating the metabolic changes that occur in ewes that are shorn in mid-pregnancy. Twenty-four twin-bearing ewes were assigned to one of two treatment groups; mid-pregnancy shorn (70 days after the mid-point of mating: P70) or unshorn. Groups were balanced for ewe age and weight. Blood samples were collected from all animals on days P53, P69, P81, P84, P90, P109 and P130, for measurement of concentrations of triiodothyronine (T3), thyroxine (T4), cortisol, glucose, non-esterified fatty acids (NEFA) and beta-hydroxybutyrate. Lamb birth weight, girth and crown-rump length (CRL) measurements were collected within 24 hrs of birth. Lambs were weighed at weaning. Mid-pregnancy shearing increased lamb birth weights and girths by 0.43 kg (P<0.05) and 2.18 cm (P<0.05) respectively although these differences were not significant once adjusted for date of birth. There was no effect on CRL. Plasma concentrations of T3 and T4 were significantly higher in mid-pregnancy-shorn ewes relative to unshorn ewes at both P81 (P<0.01) and P84 (P<0.01 and P<0.05 respectively) and T4 concentrations tended to be higher at P90 (P<0.10). There was a significant effect of shearing treatment at P81 on plasma NEFA concentrations (P<0.05). There were no significant post-shearing differences in mean cortisol, glucose or beta-hydroxybutyrate concentrations. The study proposes that the most likely mechanism by which mid-pregnancy results in higher lamb birth weights is by increasing maternal thyroid hormone concentrations, resulting in an increase in fat mobilisation causing increased NEFA concentrations in the maternal blood supply, which in turn improves placental nutrition and, thus, lamb birth weight. }, issn = {1176-5283}, author = {Sherlock RG and Kenyon PR and Morris ST and Parkinson TJ} } @conference {41314, title = {Does mid-pregnancy shearing affect lamb fleece characteristics}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {62}, year = {2002}, month = {Jan}, pages = {57-60}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {Mid-pregnancy shearing has been promoted as a technique to increase both lamb birth weight and survival in multiple-born lambs. Mid-pregnancy shearing has also been shown to increase dam wool quantity and quality and, in some instances, increase lamb growth rates until weaning. It has also been suggested that shearing of the dam during pregnancy results in a change in the lamb{\textquoteright}s fleece characteristics. The aim of this study was to further investigate the effect of dam shearing treatment on lamb fleece characteristics. Thirty-one singleton and 29 twin-born lambs were born to either mid-pregnancy shorn or unshorn Romney ewes. At 6 months of age the lambs were midside sampled (to allow measurement of staple length (SL), washing yield, loose wool bulk, colour and mean fibre diameter (MFD)). A skin biopsy was taken from the midside to measure the ratio of secondary to primary follicles. The lambs were shorn three weeks later and a fleeceweight was obtained. Lambs born to shorn dams had a higher MFD (32.9 vs. 31.3mm, P<0.05) and had slightly whiter wool (0.1 vs. 0.3, P=0.07) than their counterparts born to unshorn ewes but did not differ for yield, SL or bulk. The higher MFD found in the lambs born to shorn ewes was associated with a decrease in the number of secondary follicles (P<0.05) without a significant decrease in the number of primary fibres. There was a significant interaction (P=0.05) between birth rank and shearing treatment on fleeceweight such that twin-born lambs born to shorn dams tended to have heavier fleeces (by 170g) than those born to unshorn dams, this relationship was not observed in singleton lambs. This study suggests that for singleton lambs, mid-pregnancy shearing of the dam will have no appreciable effect on wool value. However in twin-born lambs an increase in fleece weight may offset any decreased value due to higher MFD. }, issn = {1176-5283}, author = {Sherlock RG and Kenyon PR and Morris ST} } @conference {41068, title = {Relationship between wool sulphur concentration and wool characteristics}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {59}, year = {1999}, month = {Jan}, pages = {43-45}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {It is well established that naturally occurring wool sulphur concentration is lower in high wool-producing sheep, however little is known of the relationship between wool sulphur concentration and wool fibre characteristics. Mid-side wool samples were collected from ewe hoggets differing in lamb wool sulphur concentration. Wool from hoggets, which had lower wool sulphur concentrations as lambs, had longer staple lengths, were higher yielding and had lower loose wool bulk values. There was no relationship between wool sulphur concentration and mean fibre diameter or colour. An increase in length should have a positive effect on the price of wool, especially for second shear crossbred wools. At present the price premium for bulk is poorly defined, but is unlikely to have a significant impact on the value of these wools. These findings suggest that selecting animals for low lamb wool sulphur concentration will, if anything, positively affect the per kilo price of wool produced. }, issn = {1176-5283}, author = {Kenyon PR and Sherlock RG and Lee J and Blair HT} } @conference {40735, title = {Impact of breeding technologies on the genetic gain of Merino flock}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {55}, year = {1995}, month = {Jan}, pages = {278-280}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Several breeding technologies are available to sheep breeders for increasing the rate of genetic progress in their flocks. The relative merits of these technologies depends on the selection objective and other breeding and management circumstances. This paper investigates the effects of artificial insemination (AI), progeny testing and an open-nucleus flock, on a breeding programme for fine woolled merinos. The selection objective was to decrease Mean Fibre Diameter (MFD) while maintaining Clean Fleeceweight (CFW). Two population structures were considered: a)Maintaining a closed nucleus flock of 1000 breeding ewes b)Operating an open-nucleus breeding scheme sourcing a proportion of replacements from the progeny of 5000 contributing ewes. For each structure, the benefits of AI and progeny testing were investigated individually and in combination. For the range of options considered, selection resulted in a reduction of one micron in MFD every three to five years, with no reduction in CFW. All other things equal progeny testing decreased the genetic progress possible by 0.04-0.06 u/year. An open-nucleus breeding scheme increased the rate of genetic gain by 0.06 u/year with progeny testing or 0.03 u/year in the absence of progeny testing. AI increased genetic progress by 0.06 u/year. The combination of AI and an open nucleus provided the maximum potential rate of genetic gain (0.36 u/year). To optimise the age structure for this combination of breeding technologies, the nucleus flock comprised 60\% two-tooth ewes. These results describe the impact of breeding technologies on the rate of genetic gain. To determine their cost-effectiveness, the marginal genetic gain provided by any individual technology must be weighed up against the costs and management constraints that the technology imposes. }, issn = {1176-5283}, author = {Sherlock RG and Garrick DJ} } @conference {40531, title = {Metabolic changes in sheep divergently selected for plasma IGF-1}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {53}, year = {1993}, month = {Jan}, pages = {381-384}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The detection of small amounts of biologically active material in animals may require quantification of radioactive label. Here we compare several image analysis methods for quantifying relative levels of radioactive probe detected by x-ray film or photographic emulsion. Total RNA "dot blots" and ovine muscle sections were probed for the presence of muscle actin mRNA using 35S-labelled riboprobes. Bound probe was detected by x-ray film in both cases. The probed sections were further exposed to photographic emulsion, while the dot blots were individually quantified by scintillation counting. Bound probe was quantified macroscopically by digitisation of optical density (OD) and thresholding of the x-ray film image. Dot blot image ODs were correlated with scintillation counts (r>0.96), demonstrating that the levels of mRNA detected in tissues by autoradiography are proportional to cellular mRNA concentration. Densitometry of section macroautoradiographic images can therefore be useful in determining relative probe signal at the tissue level. When probe was quantified microscopically by counting silver grains in emulsion autoradiographs, simple thresholding correlated with manual counts (r=0.88) but was unreliable at higher grain densities. Processing of the gray image gave a more direct estimate of silver grain density (r= 0.98).}, issn = {1176-5283}, author = {Sherlock RG and Blair HT and Kuhn B and MacKenzie DDS and Breier BH and Gluckman PD and McCutcheon SN} }