Context Net reproduction rate defined as number of lambs weaned for joined ewes reflects conception, litter size and the ability of ewes to rear lambs to weaning age. These three attributes can be treated as separate traits for genetic evaluation, allowing breeders to focus selection for each appropriately. Aims The aim of the present paper was to present characteristics of the data, models and genetic parameters estimated from Merino data, along with results demonstrating the predictive capacity of breeding values, for conception, litter size, rearing ability, maternal behaviour and body condition score. Methods Industry data from MERINOSELECT were used to derive phenotypes for conception, litter size and rearing ability traits separately for yearling and adult ewes, along with maternal behaviour and body condition score. Indirect traits provided correlated information, including scrotal circumference, weight, scanned fat and eye muscle depths at up to three ages (post-weaning, yearling and hogget), along with pre-joining weight and condition score for ewes. Co-variances were estimated among the 19 traits included in the analysis. Breeding values were estimated using single step genomic methodology using consensus estimates of genetic parameters, with the predictive capacity of breeding values being estimated using forward-validation. Key results Heritabilities ranged from 0.04 to 0.06 for conception, litter size and rearing ability, and were moderate for maternal behaviour (0.13) and condition score (0.20). Component traits were genetically controlled by some common genes, but with genetic correlations less than 0.5, each component can be selected for independently. Weight, fat depth and muscle depth measures were moderately to highly correlated with body condition score. These body development traits generally had low, favourable genetic correlations with ewe reproductive traits. Conclusions These procedures provide better use of data recorded by breeders subject to both data limitations and opportunities, and provide separate breeding values for conception, litter size, rearing ability, maternal behaviour and body condition score. Implications New breeding values with good predictive ability are now available for the component traits of reproduction. Direct recording data of the traits is required to achieve accuracy of breeding values. Australian Merino breeders are now able to select directly for components of reproduction and specific maternal characteristics.

中文翻译：

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新的基因组增强的美利奴绵羊繁殖育种值允许有针对性地选择受孕率、窝产仔数和母羊饲养能力

背景 净繁殖率定义为为加入母羊而断奶的羔羊数量，反映了受孕、窝产仔数和母羊饲养羔羊至断奶龄的能力。这三个属性可以被视为单独的遗传评估特征，允许育种者适当地集中选择每个属性。目的 本论文的目的是展示根据美利奴羊数据估计的数据、模型和遗传参数的特征，以及证明育种值对受孕、窝产仔数、饲养能力、母体行为和身体状况评分的预测能力的结果. 方法 使用来自 MERINOSELECT 的行业数据，分别推导出一岁母羊和成年母羊的受孕、窝产仔数和饲养能力特征的表型，以及母羊行为和身体状况评分。间接性状提供了相关信息，包括最多三个年龄（断奶后、一岁和小猪）的阴囊周长、体重、扫描的脂肪和眼肌深度，以及母羊的加入前体重和状况评分。在分析中包括的 19 个性状中估计了协方差。育种值使用单步基因组方法使用遗传参数的一致估计进行估计，育种值的预测能力使用前向验证进行估计。主要结果 受孕、窝产仔数和饲养能力的遗传力范围为 0.04 至 0.06，母亲行为 (0.13) 和状况评分 (0.20) 的遗传力中等。成分性状受一些共同基因的遗传控制，但遗传相关性小于0.5，每个组件都可以独立选择。体重、脂肪深度和肌肉深度测量与身体状况评分中度至高度相关。这些身体发育性状通常与母羊繁殖性状具有较低的、有利的遗传相关性。结论 这些程序可以更好地利用受数据限制和机会的育种者记录的数据，并为受孕、窝产仔数、饲养能力、母体行为和身体状况评分提供单独的育种值。影响 具有良好预测能力的新育种值现在可用于繁殖的组成性状。需要直接记录性状数据以实现育种值的准确性。