Journal articles on the topic 'Australian Merino sheep industry'
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1
Geenty, K. G., F. D. Brien, G. N. Hinch, R. C. Dobos, G. Refshauge, M. McCaskill, A. J. Ball, et al. "Reproductive performance in the Sheep CRC Information Nucleus using artificial insemination across different sheep-production environments in southern Australia." Animal Production Science 54, no. 6 (2014): 715. http://dx.doi.org/10.1071/an11323.
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The present paper covers reproductive performance in an artificial-insemination (AI) program of the Sheep CRC Information Nucleus with 24 699 lambs born at eight locations in southern Australia across five lambings between 2007 and 2011. Results from AI with frozen semen compared well with industry standards for natural mating. Conception rates averaged 72%, and 1.45 lambs were born per ewe pregnant for Merino ewes and 1.67 for crossbreds. Lamb deaths averaged 21% for Merino ewes and 15% for crossbreds and 19%, 22% and 20% for lambs from ewes that were mated to terminal, Merino and maternal sire types, respectively. Net reproductive rates were 82% for Merino ewes and 102% for crossbreds. From 3198 necropsies across 4 years, dystocia and starvation-mismothering accounted for 72% of lamb deaths within 5 days of lambing. Major risk factors for lamb mortality were birth type (single, twin or higher order), birthweight and dam breed. Losses were higher for twin and triplet lambs than for singles and there was greater mortality at relatively lighter and heavier birthweights. We conclude that reproductive rate in this AI program compared favourably with natural mating. Lamb birthweight for optimum survival was in the 4–8-kg range. Crossbred ewes had greater reproductive efficiency than did Merinos.
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Hutchison, Dayna, Bronwyn E. Clarke, Serina Hancock, Andrew N. Thompson, Elise Bowen, and Caroline Jacobson. "Lower Reproductive Rate and Lamb Survival Contribute to Lower Lamb Marking Rate in Maiden Ewes Compared to Multiparous Ewes." Animals 12, no. 4 (February 18, 2022): 513. http://dx.doi.org/10.3390/ani12040513.
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Suboptimal reproductive performance of maiden (primiparous) ewes remains a source of inefficiency for the Australian sheep industry. However, the extent and causes of the poorer reproductive performance of maiden ewes on Australian sheep farms are not well understood. Here, we show the reproductive performance of maiden ewes relative to their multiparous counterparts on the same farms across Australia using a cohort survey. The difference in marking rate for non-Merino maiden ewe lambs compared to multiparous ewes was 58% (74 vs. 132%; p < 0.001), and this was attributable to a 50% difference in reproductive rate (109 vs. 159%; p < 0.001) and 16% difference in lamb survival to marking (67 vs. 83%; p < 0.001). The difference in marking rate for maiden Merino two-tooth ewes lambing at approximately 2 years-of-age compared to mature multiparous ewes was 22% (80 vs. 102%; p < 0.001) and this was attributable to a 24% difference in reproductive rate (108 vs. 132%; p < 0.001) and 3% difference for lamb survival (75 vs. 78%; p < 0.05). Positive correlations for reproduction traits (reproductive rate, lamb survival and marking rate) between maidens and multiparous ewes were observed for maiden Merino two-tooth ewes (p < 0.001), but these correlations were weak or non-existent for non-Merino ewe lambs. Strategies to improve both reproductive rate and lamb survival can address the poorer and more variable reproductive performance of maiden ewes.
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Daetwyler, H. D., J. M. Hickey, J. M. Henshall, S. Dominik, B. Gredler, J. H. J. van der Werf, and B. J. Hayes. "Accuracy of estimated genomic breeding values for wool and meat traits in a multi-breed sheep population." Animal Production Science 50, no. 12 (2010): 1004. http://dx.doi.org/10.1071/an10096.
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Estimated breeding values for the selection of more profitable sheep for the sheep meat and wool industries are currently based on pedigree and phenotypic records. With the advent of a medium-density DNA marker array, which genotypes ~50 000 ovine single nucleotide polymorphisms, a third source of information has become available. The aim of this paper was to determine whether this genomic information can be used to predict estimated breeding values for wool and meat traits. The effects of all single nucleotide polymorphism markers in a multi-breed sheep reference population of 7180 individuals with phenotypic records were estimated to derive prediction equations for genomic estimated breeding values (GEBV) for greasy fleece weight, fibre diameter, staple strength, breech wrinkle score, weight at ultrasound scanning, scanned eye muscle depth and scanned fat depth. Five hundred and forty industry sires with very accurate Australian sheep breeding values were used as a validation population and the accuracies of GEBV were assessed according to correlations between GEBV and Australian sheep breeding values . The accuracies of GEBV ranged from 0.15 to 0.79 for wool traits in Merino sheep and from –0.07 to 0.57 for meat traits in all breeds studied. Merino industry sires tended to have more accurate GEBV than terminal and maternal breeds because the reference population consisted mainly of Merino haplotypes. The lower accuracy for terminal and maternal breeds suggests that the density of genetic markers used was not high enough for accurate across-breed prediction of marker effects. Our results indicate that an increase in the size of the reference population will increase the accuracy of GEBV.
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Mortimer, S. I., J. H. J. van der Werf, R. H. Jacob, D. W. Pethick, K. L. Pearce, R. D. Warner, G. H. Geesink, et al. "Preliminary estimates of genetic parameters for carcass and meat quality traits in Australian sheep." Animal Production Science 50, no. 12 (2010): 1135. http://dx.doi.org/10.1071/an10126.
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Using performance from progeny born in 2007 and 2008 generated by the Information Nucleus program of the Cooperative Research Centre for Sheep Industry Innovation, preliminary estimates of heritability were obtained for a range of novel carcass and meat attributes of lamb relevant to consumers, including carcass characteristics, meat quality and nutritional value of lamb. Phenotypic and genetic correlations of live animal traits with carcass composition and meat quality traits were also estimated. The data were from progeny located at eight sites, sired by 183 rams from Merino, maternal and terminal meat breeds and were representative of the Merino, Border Leicester × Merino, Terminal × Merino and Terminal × Border Leicester-Merino production types of the Australian sheep industry. Data were available from 7176 lambs for weaning weight, 6771 lambs for ultrasound scanning and 4110 lambs for slaughter traits. For the novel meat quality traits, generally moderate to high heritability estimates were obtained for meat quality measures of shear force (0.27 aged 1 day, 0.38 aged 5 days), intramuscular fat (0.39), retail meat colour (range of 0.09 to 0.44) and myoglobin content (0.22). The nutritional value traits of omega-3 fatty acids and iron and zinc contents tended to have low to moderate heritabilities (0.11–0.37), although these were based on fewer records. Fresh meat colour traits were of low to moderate heritability (0.06–0.21) whereas measures of meat pH were of low heritability (~0.10). For the carcass traits, estimates of heritability were moderate to high for the various measures of carcass fat (0.18–0.50), muscle weight (0.22–0.35), meat yield (0.24–0.35), carcass muscle dimensions (0.25–0.34) and bone weight (0.27). Results indicate that for most lamb carcass and meat quality traits there is sufficient genetic variation for selection to alter successfully these characteristics. Additionally, most genetic correlations of live animal assessments of bodyweight, muscle and subcutaneous fat with the carcass and meat quality traits were favourable. Appropriate definition of breeding objectives and design of selection indexes should be able to account for the small unfavourable relationships that exist and achieve the desired outcomes from breeding programs.
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Fogarty, N. M., E. Safari, P. J. Taylor, and W. Murray. "Genetic parameters for meat quality and carcass traits and their correlation with wool traits in Australian Merino sheep." Australian Journal of Agricultural Research 54, no. 7 (2003): 715. http://dx.doi.org/10.1071/ar03047.
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Estimates of genetic parameters for carcass traits in Merino sheep are presented, including muscle pH and colour, which are indicators of meat quality. The inclusion of these in the parameter set for genetic evaluation will provide the basis for more accurate estimated breeding values and the design of better breeding programs for improving meat traits in straightbred Merino sheep and crossbred lamb production. Data from 1045, nineteen-month-old Merino rams, the progeny of 125 sires from 3 strains that are representative of the industry, were used. Heritability and genetic correlations were estimated by fitting an animal model using a REML procedure in univariate and multivariate analyses. The traits included fasted pre-slaughter liveweight; dressing %; carcass tissue depth at the GR site (FATGR); fat depth at the C site (FATC); eye muscle depth (EMD), width (EMW), and area (EMA); ultimate pH and colour (L*, a*, b*) of the eye muscle. Multivariate analyses were used to estimate genetic correlations among meat traits and between wool traits (clean wool weight and mean fibre diameter) and selected carcass and meat traits. Estimates of heritability were: liveweight 0.51 (±0.10), dressing % 0.39 (±0.10), FATGR 0.33 (±0.09), FATC 0.20 (±0.08), EMD 0.27 (±0.08), EMW 0.15 (±0.07), EMA 0.23 (±0.08), muscle pH 0.27 (±0.09), and 0.14 (±0.07), 0.02 (±0.06), and 0.04 (±0.06) for the meat colour measurements L*, a*, and b* respectively. There was a favourable genetic correlation between muscle pH and colour L* of –0.56 (±0.23). There were also significant genetic correlations between wool weight and FATGR (–0.34 ± 0.16) and between mean fibre diameter and muscle colour L* (–0.66 ± 0.27). The study indicates that there is genetic variation for carcass traits, including indicators of meat quality, with scope for selection to improve meat production and quality in Merino sheep.
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Barwick, S. A., D. J. Brown, B. R. Cullis, A. K. Bell, T. J. May, M. W. Lollback, I. M. Rogan, et al. "The performance of the Border Leicester in Australia." Animal Production Science 61, no. 1 (2021): 1. http://dx.doi.org/10.1071/an19493.
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Aims We examine the average performance of Border Leicester (BL) flocks that are part of LAMBPLAN, Australia’s sheep performance recording and genetic evaluation system. We also summarise outcomes from the New South Wales Department of Primary Industry’s research on BL improvement, and discuss the performance required for the BL to continue to be a pivotal part of the Australian prime lamb industry. Key results Modest gains have been recorded in the BL in growth since 2000 and faecal egg counts have reduced, suggesting improved worm resistance. The net reproductive rate has slightly improved, while inbreeding continues to increase. In work conducted by the New South Wales Department of Primary Industries, an improved BL flock, encompassing selection for multiple births and a broadening of the breed’s genetic base, had advantages over purebred BLs in many aspects of performance, including a 19.3% advantage in the net reproductive rate. Advantages in fertility were ~5%, litter size ~7% and lamb rearing ability ~5%. BL improved × Merino and (BL improved × BL) × Merino crossbred ewes also had advantages over traditional BL × Merino ewes in their joining performance when joined to Dorset rams. Conclusions Selection in the BL needs to emphasise traits in a manner consistent with their importance to commercial lamb production. Implications Embracing this selection and broadening the BL’s genetic base will assist the BL to maintain its place in the Australian lamb industry.
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Campbell, Angus J. D., Annefleur Broekhuizen, Kimbal Curtis, Keith P. Croker, Ralph Behrendt, and Andrew N. Thompson. "A survey of post-weaning mortality of sheep in Australia and its association with farm and management factors." Animal Production Science 54, no. 6 (2014): 783. http://dx.doi.org/10.1071/an13149.
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A cross-sectional telephone survey of post-weaning sheep management and mortality was conducted involving 1410 farmers from across Australia. The average reported post-weaning mortality was 4.6%. Mortality was greatest in Queensland and Western Australia, and least in New South Wales, Victoria, and South Australia. Weaner mortality was also greater in the pastoral zone than in the sheep–cereals or high-rainfall zones. Overall, 44% of farms had mortality identified as ‘high’, exceeding the suggested benchmark of ≤4% per annum. High mortality was reported on 50% and 32% of farms with predominantly Merino and crossbred weaners, respectively. There was no statistically significant association between high mortality and the main month of lambing for a flock. Larger sheep flocks, flocks with a smaller proportion of weaners, and farms of smaller area were associated with a greater likelihood of high weaner mortality. The odds of high mortality in weaner flocks that were routinely separated according to bodyweight or condition score was half that of flocks that were managed as one group. Overall, 84% of farmers regularly provided supplementary feed to weaner sheep, but the kind of supplement offered and the proportions of farms routinely supplementing differed between states and sheep production zones. Only high-protein supplementary feeding was associated with lower odds of high mortality. This survey confirms that poor post-weaning survival remains a widespread issue for the Australian sheep industry but identifies farm and management factors associated with reduced weaner mortality.
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Swan, Andrew A., Daniel J. Brown, and Julius H. J. van der Werf. "Genetic variation within and between subpopulations of the Australian Merino breed." Animal Production Science 56, no. 1 (2016): 87. http://dx.doi.org/10.1071/an14560.
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Genetic variation within and between Australian Merino subpopulations was estimated from a large breeding nucleus in which up to 8500 progeny from over 300 sires were recorded at eight sites across Australia. Subpopulations were defined as genetic groups using the Westell–Quaas model in which base animals with unknown pedigree were allocated to groups based on their flock of origin if there were sufficient ‘expressions’ for the flock, or to one of four broad sheep-type groups otherwise (Ultra/Superfine, Fine/Fine-medium, Medium/Strong, or unknown). Linear models including genetic groups and additive genetic breeding values as random effects were used to estimate variance components for 12 traits: yearling greasy and clean fleece weight (ygfw and ycfw), yearling mean and coefficient of variation of fibre diameter (yfd and ydcv), yearling staple length and staple strength (ysl and yss), yearling fibre curvature (ycuv), yearling body wrinkle (ybdwr), post-weaning weight (pwt), muscle (pemd) and fat depth (pfat), and post-weaning worm egg count (pwec). For the majority of traits, the genetic group variance ranged from approximately equal to two times larger than the additive genetic (within group) variance. The exceptions were pfat and ydcv where the genetic group to additive variance ratios were 0.58 and 0.22, respectively, and pwec and yss where there was no variation between genetic groups. Genetic group correlations between traits were generally the same sign as corresponding additive genetic correlations, but were stronger in magnitude (either more positive or more negative). These large differences between genetic groups have long been exploited by Merino ram breeders, to the extent that the animals in the present study represent a significantly admixed population of the founding groups. The relativities observed between genetic group and additive genetic variance components in this study can be used to refine the models used to estimate breeding values for the Australian Merino industry.
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Paganoni, B. L., C. M. Oldham, M. B. Ferguson, A. N. Thompson, P. E. Vercoe, and D. G. Gordon. "Ewe nutrition during pregnancy and birthweight of lambs has minimal impact on fat and eye muscle depth in Merino progeny." Animal Production Science 53, no. 6 (2013): 509. http://dx.doi.org/10.1071/an12266.
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The hypothesis tested in this experiment was that Merino lambs with lower birthweights, due to poor ewe nutrition during pregnancy, would have more fat and less muscle than Merino lambs with higher birthweights. At two sites (Victoria and Western Australia) in each of 2 years, a wide range in the liveweight profiles of ewes was generated during pregnancy and lactation by varying the amount of supplements fed and feed on offer grazed. Progeny had fat and muscle depth at the C-site measured at various ages from 8 to 28 months of age. Across the four experiments, there were differences of 0.5 kg in birthweights and 8 kg in weaning weights between extreme treatments. The effects on the depth of fat and muscle were very small with fat depth increasing by 0.1–0.2 mm (5–7%) and muscle depth increasing by 0.2–0.7 mm (1–3%) when birthweights decreased by 1 kg. The effects of birthweight on fat depth are consistent with our hypothesis whereas the effects of birthweight on muscle depth are in contrast to our hypothesis. Nevertheless, the impacts of birthweight on the depth of fat and muscle measured at the C-site of progeny from Merino ewes, is unlikely to be of any commercial significance within the range of nutritional scenarios during pregnancy and lactation that are likely to be experienced within the Australian sheep industry.
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Vallejo Adriana, Fernández Abella Daniel, Ramos Zully, and Montossi Fabio. "Relationship between skin structure and wool traits for Ultrafine and Dohne Merino sheep of Uruguay." World Journal of Advanced Research and Reviews 12, no. 1 (October 30, 2021): 465–72. http://dx.doi.org/10.30574/wjarr.2021.12.1.0553.
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The demand in the world market for high quality fine and superfine wool is increasing, responding to greater wool textile industry demands and price incentives. There are few research studies focused on hair follicle population in fine and superfine Merino sheep in Uruguay. This study evaluates the association between wool follicle population and the most relevant economical wool traits. This work was carried out on Ultrafine Australian Merino (UAM) and Dohne Merino (DM) animals (lambs and rams). Phenotypic correlations between the secondary/primary follicles (S/P) and other wool traits (fiber diameter, staple length, clean fleece weight, scoured yield, coefficient of variation of fiber diameter and comfort factor parameter, were performed using histological skin cuts. Two skin samples were extracted from each lamb at two and nine months of age. These were processed at the skin histology laboratory to obtain a histological preparation for further biopsy, being able to differentiate the structures obtained to be evaluated. The results showed in the UAM group, S/P ratio in nine-month-old lambs was greater than two-month-old lambs (31.08 vs 23.12 P< 0.05). For DM group, there were no differences in the S/P ratio between age groups. Phenotypic correlations for wool characteristics obtained were of low to medium or null magnitude in both genotypes.
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Ferguson, M. B., J. M. Young, G. A. Kearney, G. E. Gardner, I. R. D. Robertson, and A. N. Thompson. "The value of genetic fatness in Merino ewes differs with production system and environment." Animal Production Science 50, no. 12 (2010): 1011. http://dx.doi.org/10.1071/an10130.
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Selection against fatness in the Australian sheep industry has been a priority, but defining the true value of fat requires an understanding of the effects it has on both the value of lamb carcasses and on sheep productivity. A Merino flock with 10 years of reproduction data was used to analyse the correlation between breeding values for fatness at yearling age (YFAT) and the number of lambs born per ewe mated (NLB). In 2 production years, NLB was related (P < 0.01) to YFAT resulting in an extra 14 or 24.5 lambs born per 100 ewes mated per mm of YFAT. Based on these relationships, bio-economic modelling was used to assess the whole-farm value of YFAT for different sheep production systems and for years representing a low, medium and high response of NLB to YFAT. The changes in whole-farm profitability for a 1-mm increase in YFAT varied from $1000 (2%) for a wool enterprise with a low response up to $44 000 (25%) for a lamb enterprise with a high response. Appropriate carcass value discounts for higher YFAT were investigated but were not evident because of the small change in GR fat depth associated with the range of YFAT investigated. In most years there is no impact of YFAT on NLB and therefore profitability, yet in years where Merino ewes with higher YFAT produce higher NLB, ewes with an extra 1 mm of YFAT will be up to 25% more profitable. Therefore, care is required in determining the appropriate selection pressure to be placed on YFAT in Merino selection.
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Moghaddar, N., A. A. Swan, and J. H. J. van der Werf. "Genomic prediction of weight and wool traits in a multi-breed sheep population." Animal Production Science 54, no. 5 (2014): 544. http://dx.doi.org/10.1071/an13129.
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The objective of this study was to predict the accuracy of genomic prediction for 26 traits, including weight, muscle, fat, and wool quantity and quality traits, in Australian sheep based on a large, multi-breed reference population. The reference population consisted of two research flocks, with the main breeds being Merino, Border Leicester (BL), Poll Dorset (PD), and White Suffolk (WS). The genomic estimated breeding value (GEBV) was based on GBLUP (genomic best linear unbiased prediction), applying a genomic relationship matrix calculated from the 50K Ovine SNP chip marker genotypes. The accuracy of GEBV was evaluated as the Pearson correlation coefficient between GEBV and accurate estimated breeding value based on progeny records in a set of genotyped industry animals. The accuracies of weight traits were relatively low to moderate in PD and WS breeds (0.11–0.27) and moderate to relatively high in BL and Merino (0.25–0.63). The accuracy of muscle and fat traits was moderate to relatively high across all breeds (between 0.21 and 0.55). The accuracy of GEBV of yearling and adult wool traits in Merino was, on average, high (0.33–0.75). The results showed the accuracy of genomic prediction depends on trait heritability and the effective size of the reference population, whereas the observed GEBV accuracies were more related to the breed proportions in the multi-breed reference population. No extra gain in within-breed GEBV accuracy was observed based on across breed information. More investigations are required to determine the precise effect of across-breed information on within-breed genomic prediction.
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Brown, D. J., A. A. Swan, and J. S. Gill. "Within- and across-flock genetic relationships for breech flystrike resistance indicator traits." Animal Production Science 50, no. 12 (2010): 1060. http://dx.doi.org/10.1071/an10102.
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Flystrike is a major cost for the Australian sheep industry. The industry is currently implementing selection strategies for flystrike resistance to reduce the need for breech flystrike prevention. The following indicator traits are used to select for breech flystrike resistance: wool cover, skin wrinkle on the body and breech, scouring (dags) and wool colour. The aims of this study were to estimate genetic correlations between these indicator traits and production traits using the Sheep Genetics database, to distinguish between within- and across-flock genetic relationships, and to quantify responses to selection using indexes that include breech wrinkle as a proxy trait for flystrike resistance. Breech flystrike indicator traits are all heritable; however, there are significant antagonisms between wrinkle score and some production traits, primarily fleece weight and fibre diameter. Thus, simultaneous improvement in both flystrike resistance and production will be most efficient when index selection is used. Our results show that, depending on the level of emphasis placed on breech wrinkle in the index, reductions in breech wrinkle score of 0.4–0.9 units can be achieved over a 10-year period. As across-flock relationships are generally stronger than within-flock relationships, breeders will be able to take advantage of this additional variation, depending on the relative merit of their flocks. Therefore, ram breeders should combine within-flock selection with across-flock selection where possible. Sheep Genetics released early breech wrinkle Australian Sheep Breeding Values in September 2009 to assist Merino breeders in making faster progress towards reducing breech wrinkle by using flock selection.
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Kleemann, DO, RW Ponzoni, JE Stafford, IN Cutten, and RJ Grimson. "Growth and carcass characters of the South Australian Merino and its crosses with the Booroola and Trangie Fertility Merino." Australian Journal of Experimental Agriculture 25, no. 4 (1985): 750. http://dx.doi.org/10.1071/ea9850750.
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South Australian Merino (M) and highly fecund Booroola (B) and Trangie Fertility (TF) Merino strain rams were mated to M ewes to produce M, B x M and TF x M progeny. At 4-5 months of age (24-kg slaughter group), TF x M and M lambs were heavier than B x M lambs (25.3 and 24.8 kg respectively, v. 228 kg). Similar proportional strain differences were observed at 14-1 5 months of age (38-kg slaughter group), except that, in one year, no difference was observed between the M and B x M strains, resulting in a strain x year interaction (P<0.05). When adjusted for age, TF x M carcasses were heavier than those of B x M at the first slaughter and heavier than those of B x M and M strains at the second slaughter. B x M and TF x M strains had the same fat depths and eye muscle areas, when compared at the same age, but B x M had greater fat depths and larger eye muscle areas than TF x M, relative to carcass weight; values for M were less than those of B x M and TF x M, with and without carcass weight as a covariate. Similarly, ranking of the strains did not change for carcass length, leg length and depth of thorax with and without carcass weight as a covariate. Carcasses of M lambs were longer than those of B x M, TF x M being intermediate. No differences were observed among progeny of FF and + + Booroola sires for the 12 variables measured. We conclude that carcasses of B x M and TF x M high fecundity cross Merino strains have greater depths of fat at both the same age and same carcass weight than those of the South Australian Merino, and suggest that the effect of the Booroola F gene on the characters measured is negligible. The implications of the results to the sheep industry are discussed.
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Pollott, G. E., and J. C. Greeff. "Genetic relationships between faecal egg count and production traits in commercial Merino sheep flocks." Animal Science 79, no. 1 (April 2004): 21–32. http://dx.doi.org/10.1017/s1357729800054497.
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AbstractIn several countries the gastro-intestinal parasites of sheep show evidence of resistance to the commonly used anthelmintic treatments. The use of animals with genetic resistance to such parasites has been shown to be a viable alternative in a number of resource flocks. However, the genetics of host resistance to parasites in industry flocks and the effects on production traits of using resistant sheep is relatively unknown. This study addresses these questions using data from 55 commercial Merino flocks in Australia. The heritability and genetic correlations were estimated for faecal egg count (FEC), an indicator of host resistance, and eleven fleece and body production traits. The heritability of FEC (0·26 (s.e. 0·018)), using a sire model, was found to be similar to other estimates reported in the literature from resource flocks. The heritabilities of production traits were also consistent with published reports from resource flocks. The genetic correlations between FEC and the 11 production traits, calculated using a sire model, were mostly zero, except for staple strength (-0·17 (s.e. 0·096)), fat depth (-0·26 (s.e. 0·088)) and eye-muscle depth (-0·18 (s.e. 0·091)). Animal model estimates of heritability and the genetic correlations between the traits were largely similar to the sire model estimates. Correlated responses to selection for reduced FEC based on the sire model genetic parameters were calculated to be less than 0·15% of the trait mean per generation for all traits except staple strength, fat depth, muscle depth and live weight. These were expected to increase slightly under selection for reduced FEC. Thus industry-based selection programmes to increase host resistance to parasites should be effective and have no detrimental effect on production characteristics of Merino sheep in Australia. The full benefit of such industry-based schemes could be improved by a better level of recording in the flocks studied.
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Granleese, T., S. A. Clark, A. A. Swan, and J. H. J. van der Werf. "Increased genetic gains in multi-trait sheep indices using female reproductive technologies combined with optimal contribution selection and genomic breeding values." Animal Production Science 57, no. 10 (2017): 1984. http://dx.doi.org/10.1071/an15440.
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Female reproductive technologies such as multiple ovulation and embryo transfer (MOET) and juvenile in vitro fertilisation and embryo transfer (JIVET) can produce multiple offspring per mating in sheep and cattle. In breeding programs this allows for higher female selection intensity and, in the case of JIVET, a reduction in generation interval, resulting in higher rates of genetic gain. Low selection accuracy of young females entering JIVET has often dissuaded producers from using this technology. However, genomic selection (GS) could increase selection accuracy of candidates at a younger age to help increase rates of genetic gain. This increase might vary for different traits in multiple trait breeding programs depending on genetic parameters and the practicality of recording, particularly for hard to measure traits. This study used both stochastic (animals) and deterministic (GS) simulation to evaluate the effect of reproductive technologies on the genetic gain for various traits in sheep breeding programs, both with and without GS. Optimal contribution selection was used to manage inbreeding and to optimally assign reproductive technologies to individual selection candidates. Two Australian sheep industry indexes were used – a terminal sire index that focussed on growth and carcass traits (the ‘Lamb 2020’ index) and a Merino index that focuses on wool traits, bodyweight, and reproduction (MP+). We observed that breeding programs using artificial insemination or natural mating (AI/N) + MOET, compared with AI/N alone, yielded an extra 39% and 27% genetic gain for terminal and Merino indexes without GS, respectively. However, the addition of JIVET to AI/N + MOET without GS only yielded an extra 1% genetic gain for terminal index and no extra gain in the Merino index. When GS was used in breeding programs, we observed AI/N + MOET + JIVET outperformed AI/N + MOET by 21% and 33% for terminal and Merino indexes, respectively. The implementation of GS increased genetic gain where reproductive technologies were used by 9–34% in Lamb 2020 and 37–98% in MP+. Individual trait response to selection varied in each breeding program. The combination of GS and reproductive technologies allowed for greater genetic gain in both indexes especially for hard to measure traits, but had limited effect on the traits that already had a large amount of early age records.
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Entwistle, K. W., L. J. Cummins, M. A. Hillard, J. E. Kinder, T. O'Shea, L. R. Piper, J. Thimonier, and J. F. Wilkins. "Bernard Michael Bindon — reproductive physiologist, animal scientist, research leader." Australian Journal of Experimental Agriculture 46, no. 2 (2006): i. http://dx.doi.org/10.1071/ea05222.
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This paper is a foreword to a series of papers commissioned on ‘the impact of science on the beef industry’, where the Beef CRC-related collaborative scientific work of Professor Bernard Michael Bindon will be reviewed. These papers will be presented in March 2006, as part of a ‘festschrift’ to recognise his wider contributions to the Australian livestock industries for over 40 years. Bindon’s career involved basic and applied research in many areas of reproductive physiology, genetics, immunology, nutrition, meat science and more recently genomics, in both sheep and cattle. Together with his collaborators, he made large contributions to animal science by improving the knowledge of mechanisms regulating reproductive functions and in elucidating the physiology and genetics of high fecundity livestock. His collaborative studies with many colleagues of the reproductive biology and genetics of the Booroola Merino were amongst the most extensive ever conducted on domestic livestock. He was instrumental in the development of immunological techniques to control ovulation rate and in examining the application of these and other techniques to increase beef cattle reproductive output. This paper tracks his investigations and achievements both within Australia and internationally. In the later stages of his career he was the major influence in attracting a large investment in Cooperative Research Centres for the Australian cattle industry, in which he directed a multi-disciplinary approach to investigate, develop and disseminate science and technology to improve commercial cattle productivity.
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Wiese, S. C., D. W. Pethick, J. T. B. Milton, R. H. Davidson, B. L. McIntyre, and D. N. D'Souza. "Effect of teeth eruption on growth performance and meat quality of sheep." Australian Journal of Experimental Agriculture 45, no. 5 (2005): 509. http://dx.doi.org/10.1071/ea03258.
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Two hundred and forty sheep of about 15 months of age were used in this experiment to investigate the impact of dentition category on objective and sensory meat quality. The lambs were categorised into 3 dentition classes (category 1, milk teeth; category 2, partial eruption of permanent teeth; and category 3, both permanent teeth fully erupted to the height of the central lateral milk teeth). The study was conducted on 3 farms with flocks representing the 3 genotypes that contribute to the prime lamb industry in Australia: Farm A (Merino × Merino), Farm B (first cross, Border Leicester sire × Merino ewe), and Farm C (second cross, Poll Dorset sire × Border Leicester–Merino ewe). Of the 19 meat quality attributes assessed in sheep from the 3 farms, only 1 attribute in sheep from 1 farm showed a significant deterioration in meat quality as a result of lambs progressing from dentition category 1 to 2. This was an increase in myoglobin content in lambs from Farm B (P<0.05). Many of the attributes assessed showed changes that could be considered as positive for meat quality as the lambs progressed from milk teeth to partially erupted and even to fully erupted teeth. Lambs from dentition category 3 had heavier carcass weights and higher dressing percentages compared with lambs from dentition categories 1 and 2 (P<0.05). The M. longissimus dorsi et lumborum (LD) of lambs from dentition category 3 had a lower surface lightness (L*) value, a higher myoglobin content and a lower cooking loss compared with lambs from dentition categories 1 and 2 (P<0.05). Consumer sensory assessment found the LD from lambs in dentition category 1 to have a lower acceptability score for tenderness compared with the LD from lambs in dentition category 3 (P<0.05) and a lower acceptability score for juiciness, a lower consumer rating and a lower sheep eating quality score compared with the LD from lambs in dentition categories 2 and 3 (P<0.05). The results indicate that for the range of sheep studied, meat from young sheep with partially erupted teeth is unlikely to be inferior in eating quality than the meat currently classified as lamb.
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Hodge, Marnie J., Sara de las Heras-Saldana, Sally J. Rindfleish, Cyril P. Stephen, and Sameer D. Pant. "Characterization of Breed Specific Differences in Spermatozoal Transcriptomes of Sheep in Australia." Genes 12, no. 2 (January 30, 2021): 203. http://dx.doi.org/10.3390/genes12020203.
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Reduced reproductive efficiency results in economic losses to the Australian sheep industry. Reproductive success, particularly after artificial insemination, is dependent on a number of contributing factors on both ewe and ram sides. Despite considerable emphasis placed on characterising ewe side contributions, little emphasis has been placed on characterising ram side contributions to conception success. Over 14,000 transcripts are in spermatozoa of other species, which are transferred to the ova on fertilisation. These transcripts conceivably influence early embryonic development and whether conception is successful. Semen was collected (n = 45) across three breeds; Merino, Dohne, and Poll Dorset. Following collection, each ejaculate was split in two; an aliquot was assessed utilising Computer Assisted Semen Analysis (CASA) and the remaining was utilised for RNA extraction and subsequent next-generation sequencing. Overall, 754 differentially expressed genes were identified in breed contrasts and contrast between ejaculates of different quality. Downstream analysis indicated that these genes could play significant roles in a broad range of physiological functions, including maintenance of spermatogenesis, fertilisation, conception, embryonic development, and offspring production performance. Overall results provide evidence that the spermatozoal transcriptome could be a crucial contributing factor in improving reproductive performance as well as in the overall productivity and profitability of sheep industries.
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Refshauge, G., F. D. Brien, G. N. Hinch, and R. van de Ven. "Neonatal lamb mortality: factors associated with the death of Australian lambs." Animal Production Science 56, no. 4 (2016): 726. http://dx.doi.org/10.1071/an15121.
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The objective of the present study was to examine the factors associated with the death of neonatal lambs. Postmortem autopsy data were collected from 3198 newborn lambs in the Sheep CRCs Information Nucleus Flock situated in various environments throughout southern Australia. The proportion dying by category from highest to lowest was starvation–mismothering (25%), stillbirth (21%), birth injury (18%), dystocia (9%), death in utero–prematurity (10%), predation (7%), cold exposure (5%), undiagnosed (4%), infection (1%) or misadventure (1%). Factors best explaining the probability of lambs falling into a death category included both birth type and birthweight for dystocia, stillbirth, starvation–mismothering and death in utero–prematurity. The probability of a lamb falling into any category was predicted at the mean birthweight, within birth type. Single-born lambs were more likely to die from dystocia and stillbirth, while twin lambs were more likely to die from birth injury, starvation–mismothering or from undiagnosed causes. Triplet lambs were more likely to die from starvation–mismothering or death in utero–prematurity. Sire type (Merino, maternal or terminal) did not affect the proportions of lambs within any category. The proportions lost to each cause of death were largely consistent among locations, despite the rate of death varying. Dystocia, stillbirth and birth injury, as evidenced by the presence of oedema around the head and neck or by lesions of the central nervous system, accounted for 48% of autopsied lambs. We conclude that for improvements to occur in the rates of lamb survival, the Australian sheep industry must focus on minimising losses due to dystocia, stillbirth, birth injury and starvation.
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Mortimer, S. I., D. L. Robinson, K. D. Atkins, F. D. Brien, A. A. Swan, P. J. Taylor, and N. M. Fogarty. "Genetic parameters for visually assessed traits and their relationships to wool production and liveweight in Australian Merino sheep." Animal Production Science 49, no. 1 (2009): 32. http://dx.doi.org/10.1071/ea08074.
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Heritability was estimated for a range of visually assessed traits recorded on Merino sheep, together with the phenotypic and genetic correlations among the visually assessed traits and correlations of the visually assessed traits with measured wool production traits and liveweight. Data were derived from four research resource flocks, with a range of 12 958 to 57 128 records from animals with 478 to 1491 sires for the various traits. The estimates of heritability were high for the wool quality traits of handle, wool character and wool colour (0.33–0.34) and the conformation traits of face cover, neck wrinkle and body wrinkle (0.42–0.45), moderate for front leg structure (0.18) and low for back leg structure (0.13). Fleece rot score had low heritability (0.14), while classer grade was moderately heritable (0.20). Estimates of genetic correlations among the visually assessed wool quality traits were low to moderate in size and positive (0.17–0.47). Genetic correlation estimates among the assessed conformation traits were generally very low, except for the genetic correlations between scores for neck and body wrinkle (0.92 ± 0.01) and front and back leg structure (0.31 ± 0.09). Fleece rot score had low positive genetic correlations with neck and body wrinkle scores (0.18 ± 0.05 and 0.15 ± 0.05, respectively) and classer grade (0.26 ± 0.06). Classer grade was slightly positively correlated with the wool quality traits (0.17–0.45) and leg structure traits (0.21–0.25). The genetic correlations among the visually assessed traits were generally neutral to favourable. The visually assessed wool quality traits had low to moderate favourable genetic correlations with mean and coefficient of variation of fibre diameter (0.19 –0.47), but negative correlations with clean wool yield (–0.26 to –0.37). Face cover was unfavourably correlated with staple length (–0.27 ± 0.04) and liveweight (–0.23 ± 0.02). Neck and body wrinkle scores were genetically associated with higher greasy (0.33–0.39) and clean fleece weights (0.19–0.22), greater coefficient of variation of fibre diameter (0.24–0.26) and fibre curvature (0.27–0.28), but with reduced yield (–0.26 to –0.28) and staple length (–0.34 to –0.41). Fleece rot score was genetically correlated with clean fleece weight (0.26 ± 0.05) and coefficient of variation of fibre diameter (0.27 ± 0.04). Classer grade was favourably correlated with greasy and clean fleece weights (–0.41 to –0.43), staple length (–0.29 ± 0.04), liveweight (–0.36 ± 0.03) and coefficient of variation of fibre diameter (0.27 ± 0.03). Most genetic correlations between the visually assessed traits and the measured production traits and liveweight were close to zero and less than 0.2 in magnitude. This study provides accurate values for the parameter matrix required to incorporate visually assessed traits into breeding objectives and the genetic evaluation programs used in the Australian sheep industry, allowing the development of breeding objectives and indexes that optimally combine visually assessed performance and measured production in Merino sheep.
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Grant, Emily P., Sarah L. Wickham, Fiona Anderson, Anne L. Barnes, Patricia A. Fleming, and David W. Miller. "Remote Identification of Sheep with Flystrike Using Behavioural Observations." Animals 9, no. 6 (June 18, 2019): 368. http://dx.doi.org/10.3390/ani9060368.
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Flystrike is a major problem affecting sheep in Australia. Identification of ‘flystruck’ individuals is crucial for treatment; but requires labour-intensive physical examination. As the industry moves toward more low-input systems; there is a need for remote methods to identify flystruck individuals. The aim of this study was to investigate the behaviour of sheep with breech flystrike within a paddock setting. Video footage of sixteen Merino sheep; eight later confirmed with flystrike and eight without; was collected as they moved freely within the paddock with conspecifics. Quantitative behavioural measurements and a qualitative behavioural assessment (QBA) were conducted and compared to their breech conditions (i.e., faecal/urine staining; flystrike severity). Both qualitative and quantitative assessments indicated behavioural differences between flystruck and non-flystruck animals. Flystruck sheep had a behavioural profile characterised by restless behaviour; abnormal postures and reduced grazing time (p < 0.05). Furthermore; flystruck sheep were scored to have a more ‘exhausted/irritated’ demeanour using QBA (p < 0.05). The behavioural responses also corresponded to the flystrike severity scores and condition of the breech area. We conclude that remotely assessed behaviour of flystruck sheep diverges markedly from non-flystruck sheep; and thus could be a low-input method for identifying and treating affected animals.
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Kopp, Kayla, Marta Hernandez-Jover, Susan Robertson, Angel Abuelo, and Michael Friend. "A Survey of New South Wales Sheep Producer Practices and Perceptions on Lamb Mortality and Ewe Supplementation." Animals 10, no. 9 (September 5, 2020): 1586. http://dx.doi.org/10.3390/ani10091586.
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High lamb mortality rates reduce profitability and reduce the perceived animal welfare standards of the industry. This study aimed to understand producer knowledge of lamb mortality rates and causes of lamb mortality, and to investigate various practices and perceptions of producers that may contribute to lamb deaths. Postal and online surveys gathered data on Australian sheep producer’s knowledge and practices around lambing and management practices. Based on results, approximately 50% of producers estimated less than 10% mortality of lambs between birth and marking, compared to published data estimates of 20–25% mortality. Pre-lambing vaccination of ewes was not undertaken by 10–20% of producers. Ninety-six percent of producers vaccinated lambs; however, 17% of Merino and 23% of crossbred lamb producers only gave a single vaccination instead of the recommended initial vaccine and booster. The lower estimated mortality impacts producer’s perceived benefits of management strategies being undertaken. Research undertaken needs to be more effectively distributed to producers via extension services to ensure producers understand the causes of mortality. Important messages to convey to producers include the limited impact of predation in most cases and the total costs of lamb mortality on-farm.
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Newton, J. E., D. J. Brown, S. Dominik, and J. H. J. van der Werf. "Impact of young ewe fertility rate on risk and genetic gain in sheep-breeding programs using genomic selection." Animal Production Science 57, no. 8 (2017): 1653. http://dx.doi.org/10.1071/an15321.
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Genomic selection could be useful in sheep-breeding programs, especially if rams and ewes are first mated at an earlier age than is the current industry practice. However, young-ewe (1 year old) fertility rates are known to be lower and more variable than those of mature ewes. The aim of the present study was to evaluate how young-ewe fertility rate affects risk and expected genetic gain in Australian sheep-breeding programs that use genomic information and select ewes and rams at different ages. The study used stochastic simulation to model different flock age structures and young-ewe fertility levels with and without genomic information for Merino and maternal sheep-breeding programs. The results from 10 years of selection were used to compare breeding programs on the basis of the mean and variation in genetic gain. Ram and ewe age, availability of genomic information on males and young-ewe fertility level all significantly (P < 0.05) affected expected genetic gain. Higher young-ewe fertility rates significantly increased expected genetic gain. Low fertility rate of young ewes (10%) resulted in net genetic gain similar to not selecting ewes until they were 19 months old and did not increase breeding-program risk, as the likelihood of genetic gain being lower than the range of possible solutions from a breeding program with late selection of both sexes was zero. Genomic information was of significantly (P < 0.05) more value for 1-year-old rams than for 2-year-old rams. Unless genomic information was available, early mating of rams offered no greater gain in Merino breeding programs and increased breeding-program risk. It is concluded that genomic information decreases the risk associated with selecting replacements at 7 months of age. Genetic progress is unlikely to be adversely affected if fertility levels above 10% can be achieved. Whether the joining of young ewes is a viable management decision for a breeder will depend on the fertility level that can be achieved in their young ewes and on other costs associated with the early mating of ewes.
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Pitchford, WS. "Effect of crossbreeding on components of Hogget wool production." Australian Journal of Agricultural Research 43, no. 6 (1992): 1417. http://dx.doi.org/10.1071/ar9921417.
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Australia's prime lamb industry is based on systematic three way crossbreeding. This paper examines various genetic effects on wool production, important determinants of profitability of the meat-sheep enterprise. Data from three purebred (Merino, Corriedale and Dorset Horn), six F1 and the six three-way cross lines were analysed. Direct genetic effects were important for all traits analysed. Maternal effects were generally not important. Individual heterosis was large for clean fleece weight (13%) and hogget weight (10%) and important also for fibre diameter (2%). Maternal heterosis averaged 3% for clean fleece weight, -2% for fibre diameter, and 1% for hogget weight (5% rams; -3% ewes). These results support the hypothesis that the action of individual heterosis through increased nutrient demand results in increased mature weights. Also, the effect of maternal heterosis is to increase nutrient supply resulting in increased rates of maturation.
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Knight, M. I., H. D. Daetwyler, B. J. Hayes, M. J. Hayden, A. J. Ball, D. W. Pethick, and M. B. McDonagh. "Discovery and trait association of single nucleotide polymorphisms from gene regions of influence on meat tenderness and long-chain omega-3 fatty acid content in Australian lamb." Animal Production Science 52, no. 7 (2012): 591. http://dx.doi.org/10.1071/an11229.
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Whole genome association studies in humans have shown a strong relationship between omega-3 levels in plasma and single nucleotide polymorphisms (SNP) located close to genes whose protein products are involved in the biosynthesis of long-chain omega-3 fatty acids. In sheep and other livestock species, the calpain/calpastatin system is the principal influence on natural variation in meat tenderness between animals. Using targeted next generation sequencing, we sequenced the fatty acid desaturase locus (FADS1/2/3), ELOVL2 and SLC26A10 and the calpain/calpastatin (CAPN1/2/3 and CAST) gene loci of 35 industry sires from the Australian flock. A total of 753 SNP were identified and 182 of these SNP were selected for incorporation onto a research SNP panel that represented the genetic variation across the nine genes. A total of 1252 animals were genotyped from the Australian Sheep CRC Information Nucleus Flock for these SNP and the genomic association was calculated for omega-3 fatty acid content and objective meat tenderness in lamb. Six SNP within CAST and CAPN2 showed association with shear force at Day 5 post-mortem at a significance level of P ≤ 0.01. When these were fitted simultaneously in a mixed-model analysis with fixed effects and covariates, three SNP remained significant. These SNP each had an unfavourable effect on shear force of between 1.1 and 1.8 N, with a combined effect of 4.1 N. The frequency of the favourable alleles in the progeny measured indicates that these SNP hold good potential for improving the management of meat tenderness across Merino, Border Leicester and Terminal sire types. No SNP within the FADS1/2/3, ELOVL2 and SLC26A10 gene regions were associated with lamb muscle omega-3 levels. This indicates that genetic variation in the long-chain omega-3 biosynthesis pathway genes analysed here may not be important for omega-3 content in lamb within the Information Nucleus Flock population.
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Thompson, A. N., M. B. Ferguson, A. J. D. Campbell, D. J. Gordon, G. A. Kearney, C. M. Oldham, and B. L. Paganoni. "Improving the nutrition of Merino ewes during pregnancy and lactation increases weaning weight and survival of progeny but does not affect their mature size." Animal Production Science 51, no. 9 (2011): 784. http://dx.doi.org/10.1071/an09139.
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Lamb growth to weaning, and during the period immediately following weaning, influences post-weaning mortality and may affect mature size. The hypothesis tested in the experiments reported in this paper was that changes in the maternal liveweight of Merino ewes during pregnancy and lactation could predict the weight at weaning, post-weaning survival and mature size of their progeny. At two sites (Vic. and WA) in each of two years, a wide range in the liveweight profiles of ewes was generated during pregnancy and lactation by varying the amount of supplements fed and feed on offer grazed. Across the four experiments this resulted in progeny weights ranging from 13.8 to 28.3 kg just before weaning. Lamb growth was primarily related to the amount of feed on offer during lactation, but was also related to the liveweight change of the ewe during pregnancy. These relationships were consistent in both experiments at each site. Weaning weight was strongly associated with post-weaning survival at the Vic. site. Survival rates decreased significantly when weaning weights were below 20 kg. These results indicate that management of ewe and lamb nutrition to maximise growth of lambs before weaning and growing weaners at 30 g/day or more after weaning are important for optimal post-weaning survival. The findings also suggest that the mature size of offspring is unlikely to be adversely affected by pre-weaning nutrition within the range of nutritional scenarios during pregnancy and lactation that are likely to be experienced within the Australian sheep industry.
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Brown, D. J., D. B. Savage, G. N. Hinch, and S. J. Semple. "Mob-based walk-over weights: similar to the average of individual static weights?" Animal Production Science 52, no. 7 (2012): 613. http://dx.doi.org/10.1071/an11306.
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Merino ewe liveweight represents an objective measure shown to have a profound effect on production outcomes and therefore research into technology that provides accurate and timely feedback of ewe liveweight change is warranted. Most sheep in Australia are not individually identified and therefore management of sheep is on a flock or ‘mob’ basis. Mob-based walk-over weighing (MBWOW) is a remote weighing concept for sheep flocks whereby animal weights are collected as they pass freely over a strategically placed weighing platform. The weights are then collected by the livestock manager, analysed and interpreted to aid nutritional decision making on a whole-flock basis. The hypothesis tested in this study was that data from MBWOW systems is comparable to data from static weighing sessions. At three sites, MBWOW data was collected simultaneously with monthly static weighing sessions. Raw data from MBWOW from each site was manipulated through a series of methodologies that were compared according to their relationship with the static weight data. All forms of MBWOW data showed a significant relationship with static weighing data (P < 0.05). Using a 25% filter (data within 25% of a predetermined central weight kept) and grouping data into 5-day groups strengthens the relationship between MBWOW data and static weighing data. In 1-day groupings, MBWOW data with a 25% filter and subjectively chosen central weight showed the strongest relationship (R2 = 0.89) with static weighing data. In 5-day groupings, MBWOW data with a 25% filter and reference weight from a previous weighing event as a central weight showed the strongest relationship (R2 = 0.88) to static weighing data. The former MBWOW data manipulation methodology had the least mean numerical difference (±s.d.) between MBWOW data and static weighing data (1.86 ± 0.85 kg), yet the latter had the least mean numerical difference in change-in MBWOW data and change-in static weighing data (1.51 ± 0.39 kg), and as change-in liveweight has the most application to industry, it is recommend as the preferred data manipulation technique. These findings suggest that although MBWOW is not fully congruent with static weighing, a strong relationship (R2 > 0.8) between the two and low mean numerical difference in change-in liveweight indicates that MBWOW has potential to be used to established liveweight profiles for Merino ewes that aid nutritional management.
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Pearce, K. L., D. G. Masters, R. H. Jacob, D. L. Hopkins, and D. W. Pethick. "Effects of sodium chloride and betaine on hydration status of lambs at slaughter." Australian Journal of Experimental Agriculture 48, no. 9 (2008): 1194. http://dx.doi.org/10.1071/ea08034.
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Under commercial conditions in Australia, lambs are often dehydrated at slaughter despite access to water at the abattoir. Dehydration results in reduced fluid content of meat, which causes liveweight and carcass weight loss. Two experiments evaluated hydration status and carcass characteristics in lambs fed increased levels of sodium chloride (salt) and/or betaine before slaughter. Both experiments were 2 × 2 factorial designs with two levels of salt added [0 and 50 g/kg dry matter (DM)] and two levels of betaine added (0 and 6.7 g/kg DM) to the diets. The treatment diets were introduced to sheep over a 7–8-day period and then fed at 1.5 kg/day for the following 7 days. In experiment 1, 96 Poll Dorset–Merino cross wether lambs (45.9 ± 0.17 kg) were fed in individual pens and in experiment 2, 204 Merino wether lambs (43.1 ± 0.35 kg) were fed in group pens. In the first experiment, water and feed were withheld from the end of the treatment feeding period until slaughter 48 h later. In the second experiment, feed and water were withheld for the first 24 h after treatment but water was available for the next 24 h immediately before slaughter. In both experiments, consumption of the high salt diet decreased urine specific gravity and osmolarity at the end of the feeding period and after 24 h without access to water. This indicates an improved hydration status at this time. However, the difference in hydration status related to feeding salt declined during the 48-h lairage period and there were no significant differences in hot carcass weight or muscle DM among groups at slaughter. It could be concluded from this result that the addition of salt has little commercial value; however, this may not be the case. The lambs in experiment 2 did not behave according to industry expectations. They all drank water in the last 24 h in lairage and none of the groups showed severe dehydration. Further research is justified to determine if the lambs fed the diets with no added salt drunk in lairage as a learned response from the lambs fed salt and, if so, whether this can be developed into a commercial strategy. Feeding betaine did not result in any changes in hydration status or carcass characteristics.
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Parsons, Y. M., D. W. Cooper, L. R. Piper, Y. M. Parsons, and D. W. Cooper. "Genetic variation in Australian Merino sheep." Animal Genetics 27, no. 4 (April 24, 2009): 223–28. http://dx.doi.org/10.1111/j.1365-2052.1996.tb00482.x.
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Board, P. G. "Erythrocyte oxidized glutathione in Australian Merino sheep." Animal Blood Groups and Biochemical Genetics 6, no. 2 (April 24, 2009): 65–69. http://dx.doi.org/10.1111/j.1365-2052.1975.tb01353.x.
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Lakota, E. А. "PRESERVATION OF GENETIC POTENTIAL OF STAVROPOL SHEEP BREED FOR POVOLZHYE DREY STEPPE ZONE." Vestnik of Ulyanovsk state agricultural academy, no. 3(50) (September 8, 2020): 179–84. http://dx.doi.org/10.18286/1816-4501-2020-3-179-184.
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In conditions of Povolzhye steppe zone development of productive qualities of Stavropol breed sheep was conducted by meat merino sheep. Experimental research was carried out in ZAO «Novaya Zhizn» in Novouzensky district of Saratov region, located in semi desert zone, bordering upon South-West Khazakhstan. The research aim was the increase and maintenance of genetic potential of Stavropol breed sheep of Povolzhye population. Working procedure is based on guidelines of the All-Union Academy of Agricultural sciences, All Union research institute of sheep and goat breeding. The study materials were Stavropol pure breed sheep and 1/8 –thoroughbred cross breed with Australian meat merino herdmates. As the result of stepped breeding of local Stavropol ewe with half bred by Australian meat merino ram- breeder of Stavropol breed animals of 1/2 ,1/4, 1/8 –blood were obtained, which then one- shear tupped by breeding «inter se». It is proved that in applying such selective method 1/8-blood by Australian meat merino sheep were characterized with higher body weight, better wool quality in contrast to Stavropol pure –breed herdmates. So, in 1/8-blood by Australian meat merino of hybrid ewe during breeding «inter se» live body at birth was higher than at pure breed herdmates for 5,56 %, during ablactation –at the age of 4 months - for 6,38 % (difference isn’t accurate). According to sharing of wool in grease, superiority of ewe of hybrid origin over pure breed was 5,6 % (Р≥0,99), but in terms of washed fiber it increases to 8,3 % (Р≥0,999). So, in dry steppe zone of Povolzhye new improved, according to its productive qualities, genotype of Stavropol breed sheep is created with retention of genetic resource that is essential economic factor for the modern maintenance of fine-wool sheep breeding field.
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Hatcher, S., K. D. Atkins, and E. Safari. "Lamb survival in Australian Merino Sheep: A genetic analysis12." Journal of Animal Science 88, no. 10 (October 1, 2010): 3198–205. http://dx.doi.org/10.2527/jas.2009-2461.
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Behrendt, Karl. "Price risk exposure of Australian Merinos – is it in the bloodline?" Animal Production Science 54, no. 9 (2014): 1317. http://dx.doi.org/10.1071/an14305.
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Sheep producers and their advisors utilise Australian Merino bloodline trial data to guide future sheep breeding objectives and ram selection. To adequately assess the economic outcomes from different bloodlines in the decision making process, there is a need to consider the impact of wool and sheep meat price risk. Using a steady-state wether flock model that accounts for the lifetime productivity of 268 reported Merino bloodlines and stochastic dependency in weekly wool and sheep meat prices from 28 June 2005 to 10 November 2011, gross incomes per dry sheep equivalent (GI/DSE) were calculated for a weekly time step. The analysis found that across all bloodlines and market price scenarios, GI/DSE ranged between AU$13.92 and AU$67.83, with an overall mean of AU$32.60. The individual means of bloodlines across the time series ranged from AU$37.46 to AU$25.19 GI/DSE. The coefficient of variation, used as the measure of relative risk for each bloodline, ranged from 0.24 to 0.30 with a mean of 0.25. The analysis showed that a bloodlines exposure to price risk has a curvilinear relationship to fibre diameter and fleece weight. The results from a risk-reward point of view indicate that the majority of Australian Merino bloodlines are risk-inefficient. This suggests Australian sheep producers have a significant opportunity to increase net returns and reduce price risk exposure by identifying and switching to more risk-efficient bloodlines.
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Torekhanov, A. A., and N. K. Zhumadillayev. "ETTI MERINOS – KAZAKHSTANI EXPORT-ORIENTED MEAT BREAD." REPORTS 335, no. 1 (February 12, 2021): 146–51. http://dx.doi.org/10.32014/2021.2518-1483.21.
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Sheep breeding in Kazakhstan is a traditional branch of animal husbandry. The development of the industry is facilitated by the presence of large areas of pasture lands, as well as the existing valuable gene pool of breed resources, created by national selection and long-term work of scientists-breeders. The republic has great potential for the further development of sheep breeding industry and is able not only to meet the population's need for mutton, but also to become a major exporter. The restoration and further development of domestic sheep breeding should be based on rational use of genetic potential of animals and natural pastures of the country for the cost-effective production of high quality sheep products that meet international standards. The article deals with the development of fine-wool sheep breeding in Almaty, Zhambyl and South Kazakhstan regions, improvement of meat characteristics of the South Kazakh merino. The experience of using "etti merino" rams-producers in farms of Turkestan region showed that meat merino rams have a positive effect on meat productivity of the South Kazakh merino, and at the same time do not worsen their wool characteristics. The information on the population number of sheep of "Etti Merino" breed for 2020, the class composition of the ewes on farms, productivity of rams-producers in a number of generations, assessment of the quality of the offspring of 6-7 month old rams, wool productivity of the breeding groups of female sheep are presented.
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Brown, D. J., and N. M. Fogarty. "Genetic relationships between internal parasite resistance and production traits in Merino sheep." Animal Production Science 57, no. 2 (2017): 209. http://dx.doi.org/10.1071/an15469.
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Breeding Merino sheep that are resistant to internal parasites alleviates the high costs associated with treatment of worm infestation and loss of production, as well as mitigating the development of anthelmintic resistance among the major worm species. Faecal worm egg count ((cube root transformation), wec) can be used in sheep as a measure of internal parasite resistance. Accurate estimates of genetic parameters for wec are required for calculation of Australian Sheep Breeding Values and inclusion of worm resistance in sheep breeding programs. This study provides updated estimates of heritability for wec and its genetic correlations with production traits. Data were analysed from a wide range of Australian and New Zealand Merino sheep in the MERINOSELECT database, which included 141 flocks with 801 flock years and up to 217 137 animals with wec recorded in at least one of four ages (W = weaning, P = post weaning, Y = yearling, H = hogget). The heritability estimates ranged from 0.16 ± 0.01 for Ywec to 0.29 ± 0.01 for Wwec, with generally high genetic correlations between the ages. Bivariate analyses estimated genetic correlations between wec at the various ages and growth, carcass quality, reproduction and wool production traits at various ages. These genetic correlations were generally small or close to zero, albeit with some significantly different from zero. The moderate heritability for wec (0.2–0.3) and its high phenotypic variation (coefficient of variation >30%) shows that relatively rapid selection response for worm resistance could be achieved. Inclusion of wec in sheep breeding programs to increase worm resistance would be expected to have little if any impact on other important production traits. These genetic parameters have been incorporated into MERINOSELECT by Sheep Genetics to provide Australian Sheep Breeding Values for wec and appropriate indices for wool and meat production. There is evidence that genotype × environment interactions may be important in some environments by reducing the accuracy of Australian Sheep Breeding Values for wec. Hence it may be prudent for breeders to implement strategies that manage the risk of any impact of genotype × environment on their breeding program.
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Parsons, Y. M., M. R. Fleet, and D. W. Cooper. "The Agouti gene: a positional candidate for recessive self-colour pigmentation in Australian Merino sheep." Australian Journal of Agricultural Research 50, no. 6 (1999): 1099. http://dx.doi.org/10.1071/ar98099.
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The occurrence of self-colour pigmentation in the Australian Merino wool flock is of considerable economic importance. The Agouti gene is believed to be responsible for the recessive expression of pigmented fleece. Using comparative mapping information we have investigated the putative homologous ovine map positon of the Agouti gene for linkage to the recessive self-colour phenotype of Australian Merino sheep. Significant results were observed with microsatellites previously mapped to ovine chromosome 13. Comparative data suggest that the ovine Agouti gene would map to the same chromosome, making the Agouti gene a positional candidate for the self-colour phenotype.
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Huisman, A. E., and D. J. Brown. "Genetic parameters for bodyweight, wool, and disease resistance and reproduction traits in Merino sheep. 3. Genetic relationships between ultrasound scan traits and other traits." Animal Production Science 49, no. 4 (2009): 283. http://dx.doi.org/10.1071/ea08172.
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The Australian Merino is the predominant genetic resource for both the lamb and sheep meat industries of Australia. There are very few studies that provide information on the relationships between wool and non-wool traits. This paper describes the genetic relationships between ultrasound scan traits and wool, disease resistance and reproduction traits in Merino sheep. Fleece weight and fibre diameter coefficient of variation were negatively correlated with ultrasound scanned fat and eye muscle depth (–0.10). Staple length, fibre curvature, and scrotal circumference were not correlated with scanned fat or eye muscle depth. Staple strength, number of lambs born and number of lambs weaned had a positive genetic correlation with fat and eye muscle depth (0.20–0.30). Faecal egg count had a negative genetic correlation with scanned fat (–0.10) and scanned eye muscle depth (–0.20). Results indicate that the combined improvement of carcass and wool characteristics in Merino sheep is possible.
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Tammen, Imke, Roger W. Cook, Frank W. Nicholas, and Herman W. Raadsma. "Neuronal ceroid lipofuscinosis in Australian Merino sheep: a new animal model." European Journal of Paediatric Neurology 5 (January 2001): 37–41. http://dx.doi.org/10.1053/ejpn.2000.0432.
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Murray, J. D., C. Moran, M. P. Boland, C. D. Nancarrow, R. Sutton, R. M. Hoskinson, and R. J. Scaramuzzi. "Polyploid cells in blastocysts and early fetuses from Australian Merino sheep." Reproduction 78, no. 2 (November 1, 1986): 439–46. http://dx.doi.org/10.1530/jrf.0.0780439.
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Ponnampalam, E. N., K. L. Butler, D. L. Hopkins, M. G. Kerr, F. R. Dunshea, and R. D. Warner. "Genotype and age effects on sheep meat production. 5. Lean meat and fat content in the carcasses of Australian sheep genotypes at 20-, 30- and 40-kg carcass weights." Australian Journal of Experimental Agriculture 48, no. 7 (2008): 893. http://dx.doi.org/10.1071/ea08054.
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Lean meat and fat content of Australian sheep genotypes were compared at 20-, 30- and 40-kg carcass weights. Sheep comprised Poll Dorsetgrowth × Border Leicester Merino (PDg × BLM), Poll Dorsetgrowth × Merino (PDg × M), Poll Dorsetmuscling × Merino (PDm × M), Border Leicester × Merino (BL × M) and Merino × Merino (M × M) genotypes. Lambs were raised as a mixed flock under grazing and slaughtered at 4, 8, 14 and 22 months of age with each slaughter time involving ~150 mixed sex animals. At 24 h after slaughter, chilled carcasses were halved along the backbone and the right sides were used for determination of lean, fat and ash percentages using dual energy X-ray absorptiometry. Within a particular age group and genotype, animals growing at faster rates and reaching heavier carcass weights had lower carcass lean meat content than slower growing animals. Merino carcasses weighing 20 and 30 kg had similar levels of lean meat to PD × M genotypes, which was greater than that from the BL × M genotype. Second-cross PD × BLM carcasses weighing 20 kg at 4 months and 30 kg at 8 months had similar carcass fat and lean percentages to 20-kg Merino carcasses at 8 months and first-cross PD × M carcasses weighing 30 kg at 14 months, respectively. At 40-kg carcass weight, 22-month-old Merinos had similar levels of leanness to carcasses from 22-month-old PD × M animals and carcasses from 14-month-old second-cross PD × BLM animals. Carcass lean meat content decreased with increasing carcass weight and first- cross BL × M animals had the lowest carcass lean across all weight categories. There was a major acceleration in carcass fatness between 14 and 22 months associated with a reduction in muscle deposition. Results indicate that age of the animal should be taken into account when carcass lean and fat contents are compared at a particular carcass weight. Merinos will achieve weight/composition specifications at least equally well to crossbreds but will take longer with a likely increase in production costs.
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Britt, AG, CL Cotton, BH Kellett, IH Pitman, and JA Trask. "Structure of the Epidermis of Australian Merino Sheep Over a 12-Month Period." Australian Journal of Biological Sciences 38, no. 1 (1985): 165. http://dx.doi.org/10.1071/bi9850165.
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Light-microscopic examination of frozen sections of skin taken from the dorsal thoraco-Iumbar region of Australian Merino sheep in winter revealed that the thickness of the epidermis plus a sudanophilic layer was 24�9 !tm in the interfollicular region. The uncornified epidermis (10�9 !till) was separated from the sudanophilic layer (14�0 !tm) by a thin stratum corneum. It was concluded that the bulk of the sudanophilic layer was emulsified sebum in which was embedded a disorganized collection of desquamated cornified cells. Although large variances were observed in the thickness of the uncornified epidermis and of the sudanophilic layers between sheep and both within the between blocks of tissue obtained from individual sheep, there were no strong seasonal effects on either epidermal structure or layer thickness over a 12-month period. These results suggest that the Australian Merino differs from Finnish Landrace x Dorset Horn ewes, which are reported to possess, at least in winter, a thicker uncornified epidermis and a thicker stratum corneum that could be divided into two zones and was uniformly permeated by lipid.
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Rowe, J. B. "The Australian sheep industry - undergoing transformation." Animal Production Science 50, no. 12 (2010): 991. http://dx.doi.org/10.1071/an10142.
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Changes in the sheep industry over the last 20 years represent a trend that is unlikely to be reversed. The farm gate value of wool production has decreased from over $6 billion to ~$2.5 billion and the value of sheep meat has increased from $0.5 to $2.2 billion. Wool and meat are now on an equal footing in terms of the economic value of each sector of the industry. Future profitability of both wool and sheep meat production depends on achieving a high rate of productivity gain and improving quality attributes valued by consumers. Wool and sheep meat cannot compete on price or volume with synthetics and cotton in the textile market or with chicken and pork in the meat market. Differentiation based on quality and consistency needs to be measurable and clearly understood by consumers. The combination of genetic selection and good management can deliver improved productivity gain. Skills development and training will be essential for the industry to fully utilise available knowledge and new technologies.
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Salvatore, L., D. Allen, K. L. Butler, D. Tucman, A. Elkins, D. W. Pethick, and F. R. Dunshea. "Factors affecting the concentration of short branched-chain fatty acids in sheep fat." Australian Journal of Experimental Agriculture 47, no. 10 (2007): 1201. http://dx.doi.org/10.1071/ea07037.
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The concentration of short branched-chain fatty acids, specifically 4-methyloctanoic acid (MOA) and 4-methylnonanoic acid (MNA), in subcutaneous fat were determined in five genotypes (Poll Dorset × Border Leicester Merino, Poll Dorset × Merino, Poll Dorsetmuscling × Merino, Merino × Merino, Border Leicester × Merino) of Australian sheep. In total, 264 ewes and wethers, either 8 or 22 months of age, were selected for genotype, age and gender. These animals were sired by 16 rams that were selected for growth based on estimated breeding values (EBVs), except for one group (Poll Dorsetmuscling × Merino), which was selected for muscling based on EBVs. There was a strong relationship between the concentration of MOA and MNA at 8 and 22 months of age. There were no differences between lambs sired by Poll Dorset rams selected for muscling or growth. The 8- and 22-month-old Poll Dorset × Merino sheep had higher levels of MOA and MNA compared with the other genotypes (P < 0.001). At 8 months of age, the wethers had higher levels of MOA and MNA (P < 0.001) than the ewes of the same genotype. There was a strong relationship (P < 0.001) between MOA and MNA and the fat and lean percentage for 22-month-old ewes. Effects of sire, dam and slaughter day (at the same slaughter age) on MOA and MNA were also found. The results suggest that there is good feasibility for selection against animals at risk of possessing higher levels of short branched-chain fatty acids.
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LUSHNIKOV, V. P. "MEAT PRODUCTIVITY OF RAMS OBTAINED BY CROSSING VOLGOGRAD SHEEPS WITH RAMS OF DIFFERENT FOREIGN BREEDS." Sheep, goats, woolen business, no. 2 (2021): 23–25. http://dx.doi.org/10.26897/2074-0840-2021-2-23-25.
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The article presents the indicators of slaughter, morphological and chemical composition of lamb meat obtained from industrial crossing of Volgograd breed queens with sheep breeds: Poll Dorset, Australian meat merino, North Caucasian meat-wool, Suff olk, Ile-de-France and Merinoland.
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Z, Hernández-Russo. "Effect of Gastrointestinal Nematodes on Reproduction and Lamb Growth in Australian Merino Sheep." Open Access Journal of Veterinary Science & Research 5, no. 2 (2020): 1–5. http://dx.doi.org/10.23880/oajvsr-16000204.
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Environmental conditions in Uruguay favour the development of gastrointestinal nematodes (GIN) throughout the year, with clinical or subclinical manifestations that cause significant economic losses. The aim of this study was to evaluate the effect of the GIN on fertility, fecundity, reproductive rate and lamb growth in Australian Merino sheep grazing on basalt fields. The study was carried out in a farm located in north of Uruguay. Sixty-eight Merino ewes facing a natural parasite challenge were divided into two groups. Control group was doused with active anthelmintic that have proven efficacy to minimize the effects of parasitic and the parasitized group that did not receive anthelmintic, except rescue dosages. Stool sample of each sheep was collected monthly for egg counts (EPG) of GIN using McMaster technique and nematode genders were identified from infective larvae obtained in cultures by Roberts O’ Sullivan technique. Artificial insemination and ewes were mated for new service, and pregnancy condition was diagnosed by ultrasound. Lambing control was made and lambs were weighed at birth and marking. The evolution of EPG values showed significant differences between groups at the end of gestation and lactation. Haemonchus spp. was the main gender of nematodes found, followed by Trichostrongylus spp. Fertility was 95 % versus 90 %; fecundity 87 % versus 63 % and reproductive rate 73 % versus 47 % for the control group and the parasitized one respectively. No significant differences were recorded in birth-weight. However market-weight and lamb daily gain were lower in the parasitized group. The effect of natural infection GIN was evident in lower reproductive performance of Australian Merino sheep.
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Cottle, D. J., M. T. Harrison, and A. Ghahramani. "Sheep greenhouse gas emission intensities under different management practices, climate zones and enterprise types." Animal Production Science 56, no. 3 (2016): 507. http://dx.doi.org/10.1071/an15327.
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Greenhouse gas emissions (GHG) from broadacre sheep farms constitute ~16% of Australia’s total livestock emissions. To study the diversity of Australian sheep farming enterprises a combination of modelling packages was used to calculate GHG emissions from three sheep enterprises (Merino ewe production for wool and meat, Merino-cross ewes with an emphasis on lamb production, and Merino wethers for fine wool production) at 28 sites across eight climate zones in southern Australia. GHG emissions per ha, per dry sheep equivalents and emissions intensity (EI) per tonne of clean wool or liveweight sold under different pasture management or animal breeding options (that had been previously determined in interviews with farmers) were assessed relative to baseline farms in each zone (‘Nil’ option). Increasing soil phosphorus fertility or sowing 40% of the farm area to lucerne resulted in the smallest and largest changes in GHG/dry sheep equivalents, respectively (–66%, 113%), though both of these options had little influence on EI for either clean wool or liveweight sold. Breeding ewes with greater body size or genotypes with higher fleece weight resulted in 11% and 9% reductions, respectively, in EI. Enterprises specialising in lamb production (crossbred ewes) had 89% lower EI than enterprises specialising in fine wool production (Merino wethers). Thus, sheep producers aiming for lower EI could focus more on liveweight turnoff than wool production. Emissions intensities were typically highest in cool temperate regions with high rainfall and lowest in semiarid and arid regions with low aboveground net primary productivity. Overall, animal breeding options reduced EI more than feedbase interventions.
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Haba, M. De La, A. Moreno, D. Llanes, and E. M. Tucker. "Glutathione concentrations in the red cells of Merino sheep." Journal of Agricultural Science 110, no. 2 (April 1988): 401–3. http://dx.doi.org/10.1017/s002185960008148x.
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Tasmanian Merino sheep show a bimodal distribution in the concentration of reduced glutathione (GSH) in their red cells, 40% of sheep having GSH values of around 27 mg GSH/100 ml red cells and 60% with values of about 92 mg GSH/100 ml red cells (Tucker & Kilgour, 1972). The GSH deficiency was shown to be due to an impaired activity of γ-glutamyl cysteine synthetase (γ-GC-S), the enzyme catalysing the first step of GSH biosynthesis (Tucker, Kilgour & Young, 1976). Family data indicated that the deficiency in this strain of Merinos was under the control of a dominant gene, designated GSHL (Tucker et al. 1976). In contrast, Board, Roberts & Evans (1974) reported that a similar type of GSH deficiency in Australian Merino sheep was under the control of a recessive gene. The reasons for this apparent discrepancy remain unresolved.
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Al-Atiyat, R., W. Flood, I. Franklin, B. Kinghorn, and A. Ruvinsky. "Microsatellite-based genetic variation and differentiation of selected Australian Merino sheep flocks." Small Ruminant Research 136 (March 2016): 137–44. http://dx.doi.org/10.1016/j.smallrumres.2016.01.018.
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FLANAGAN, M., SJ JOHNSON, D. HOFFMANN, IG POLKINGHORNE, DJ REID, and MA SHEPHERD. "Clinical pathology of Australian bluetongue virus serotype 16 infection in Merino sheep." Australian Veterinary Journal 70, no. 3 (March 1993): 101–4. http://dx.doi.org/10.1111/j.1751-0813.1993.tb03286.x.
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