Scotland's Rural College (SRUC), Midlothian, Scotland, UK.
Teagasc, Animal & Grassland Research and Innovation Centre, Moorepark, Ireland.
J Anim Breed Genet. 2022 May;139(3):342-350. doi: 10.1111/jbg.12668. Epub 2022 Feb 1.
Genetic evaluations in sheep have proven to be an effective way of increasing farm profitability. Much research has previously been conducted on producing within-country genetic evaluations; however, to date, no across-country sheep genetic evaluations have been produced between Ireland and the UK. The objective of the present study was to examine the feasibility of an across-country genetic evaluation of live body weight and carcass composition traits for Texel sheep raised in Ireland and the UK. The benefit of genetic selection based on across-country genetic evaluations, in comparison with within-country genetic evaluations, was also quantified. Animal traits included early-life and postweaning live body weights, and muscle and fat depth ultrasound measurements. Irish and UK data were combined, common animals with progeny with records in both countries were identified and a series of bivariate analyses were performed separately for each trait to produce across-country genetic evaluations. Fixed effects included contemporary group, age at first lambing of the dam, parity of the dam (Ireland), dam age at lamb's birth (UK), a gender by age of the lamb interaction, a birth type by rearing type of the lamb interaction and country of birth of the lamb. Random effects included the animal additive genetic, dam maternal, litter common environment and residual effect. The model for postweaning weight, muscle depth and fat depth included only the animal additive genetic and litter common environmental random effects. Genetic correlations between the two countries ranged from 0.82 to 0.88 for the various traits. Across-country breeding values were estimated for all animals and response to selection was predicted using the top 10 and top 20 sires in both within- and across-country analyses for the two countries. Overall, results showed that rates of genetic gain could potentially increase from between 2.59% and 19.63% from selection based on across-country genetic evaluations compared to within-country evaluations alone. Across-country evaluations are feasible and would be of significant benefit to both the Irish and UK sheep industries. In order to realize these potential gains though, there would need to be a switch in emphasis by sheep breeders towards using objective traits as their primary selection criteria.
绵羊的遗传评估已被证明是提高农场盈利能力的有效方法。之前已经有很多关于在国内进行遗传评估的研究；然而，迄今为止，爱尔兰和英国之间还没有进行跨国绵羊遗传评估。本研究的目的是检验对爱尔兰和英国饲养的特克赛尔绵羊活体体重和胴体组成性状进行跨国遗传评估的可行性。还量化了基于跨国遗传评估的遗传选择与国内遗传评估相比的优势。动物性状包括早期和断奶后活体体重，以及肌肉和脂肪深度超声测量。将爱尔兰和英国的数据合并，确定了具有两国记录后代的共同动物，并针对每个性状分别进行了一系列二元分析，以产生跨国遗传评估。固定效应包括当代群体、母羊的首次产羔年龄、母羊的产次（爱尔兰）、羔羊出生时母羊的年龄（英国）、羔羊性别与年龄的互作、羔羊出生类型与饲养类型的互作以及羔羊的出生国家。随机效应包括动物加性遗传、母羊母体、产羔共同环境和残差效应。断奶后体重、肌肉深度和脂肪深度模型仅包括动物加性遗传和产羔共同环境随机效应。两国之间的遗传相关系数在不同性状之间从 0.82 到 0.88 不等。对所有动物进行了跨国育种值估计，并使用两国国内和跨国分析中排名前 10 和前 20 的种公羊预测了选择的反应。总体而言，结果表明，与仅基于国内遗传评估相比，基于跨国遗传评估的选择可能会使遗传增益率提高 2.59%至 19.63%。跨国评估是可行的，对爱尔兰和英国的绵羊产业将有重大意义。然而，为了实现这些潜在收益，绵羊饲养者需要将重点从使用主观性状作为主要选择标准转变为使用客观性状。
