Abstract：
Genetic selection focused purely on production traits has proven very successful in improving the productive performance of livestock. However, heightened environmental and infectious disease challenges have raised the need to also improve the resilience of animals to such external stressors, as well as their efficiency in utilising available resources. A better understanding of the relationship between efficiency and production and health traits is needed to properly account for it in breeding programmes and to produce animals that can maintain high production performance in a range of environmental conditions with minimal environmental footprint. The aim of this study was to perform a meta-analysis of genetic parameters for production, efficiency and health traits in sheep and goats. The dataset comprised 963 estimates of heritability and 572 genetic correlations collated from 162 published studies. A threelevel meta-analysis model was fitted. Pooled heritability estimates for milk production traits ranged between 0.27 ± 0.03 and 0.48 ± 0.13 in dairy goats and between 0.21 ± 0.06 and 0.33 ± 0.07 in dairy sheep. In meat sheep, the heritability of efficiency traits ranged from 0.09 ± 0.02 (prolificacy) up to 0.32 ± 0.14 (residual feed intake). For health traits, pooled heritability was 0.07 ± 0.01 (faecal egg count) and 0.21 ± 0.01 (somatic cell score) in dairy goats and 0.14 ± 0.04 (faecal egg count) and 0.13 ± 0.02 (somatic cell score) in dairy sheep. In meat sheep, the heritability of disease resistance and survival traits ranged between 0.07 ± 0.02 (mastitis) and 0.50 ± 0.10 (breech strike). Pooled estimates of genetic correlations between resilience and efficiency traits in dairy goats were not significantly different from zero with the exception of somatic cell score and fat content (-0.19 ± 0.01). In dairy sheep, only the unfavourable genetic correlation between somatic cell score and protein content (0.12 ± 0.03) was statistically significant. In meat sheep only, the correlations between growth and faecal egg count (-0.28 ± 0.11) as well as between growth and dagginess (-0.33 ± 0.13) were statistically significant and favourable. Results of this meta-analysis provide evidence of genetic antagonism between production and health in dairy sheep and goats. This was not observed in meat sheep where most of the pooled estimates had high standard errors and were non-significant. Based on the obtained results, it seems feasible to simultaneously improve efficiency and health in addition to production by including the different types of traits in the breeding goal. However, a better understanding of potential trade-offs between these traits would be beneficial. Particularly, more studies focused on reproduction and resilience traits linked to the animal\'s multi-trait response to challenges are required.
摘要：
事实证明，纯粹专注于生产性状的遗传选择在改善牲畜的生产性能方面非常成功。然而,日益严峻的环境和传染病挑战也提高了动物对这些外部压力源的抵御能力的必要性，以及他们利用可用资源的效率。需要更好地了解效率与生产和健康特性之间的关系，以便在育种计划中适当考虑它，并生产能够在一系列环境条件下以最小的环境足迹保持高生产性能的动物。这项研究的目的是对生产的遗传参数进行荟萃分析，绵羊和山羊的效率和健康性状。该数据集包括从162项已发表的研究中整理的963项遗传力估计和572项遗传相关性。拟合了三级荟萃分析模型。产奶性状的汇总遗传力估计值在奶山羊中介于0.27±0.03和0.48±0.13之间，在奶羊中介于0.21±0.06和0.33±0.07之间。在肉羊中，效率性状的遗传力范围为0.09±0.02（繁殖力）至0.32±0.14（剩余采食量）。对于健康特征，乳山羊的合并遗传力为0.07±0.01（粪便卵数）和0.21±0.01（体细胞评分），乳羊的合并遗传力为0.14±0.04（粪便卵数）和0.13±0.02（体细胞评分）。在肉羊中，抗病性和生存性状的遗传力在0.07±0.02（乳腺炎）和0.50±0.10（臀位）之间。除了体细胞得分和脂肪含量（-0.19±0.01）外，奶山羊的弹性和效率性状之间的遗传相关性的汇总估计与零无显着差异。在奶羊中，只有体细胞评分与蛋白质含量之间的不利遗传相关性（0.12±0.03）有统计学意义。只在肉羊中，生长与粪便卵数之间的相关性（-0.28±0.11）以及生长与dagg之间的相关性（-0.33±0.13）在统计学上是显着且有利的。这项荟萃分析的结果提供了奶牛和山羊的生产与健康之间的遗传拮抗作用的证据。这在肉羊中没有观察到,其中大多数合并的估计具有高的标准误差并且不显著。根据获得的结果，通过在育种目标中包括不同类型的性状，除了生产外，同时提高效率和健康似乎是可行的。然而,更好地理解这些特征之间的潜在权衡将是有益的。特别是,需要更多的研究集中在与动物对挑战的多性状反应相关的繁殖和弹性特征上。
