The main aim of the current study was to perform a genetic analysis of two live body weight and two carcass composition traits in purebred UK-born Texel, Suffolk and Charollais lambs separately in order to produce future across country evaluations. The two live body weight traits considered were early-life weight (40–85 days of age) and scan weight (121–180 days of age), and the two carcass composition traits were muscle depth and fat depth. Only records from lambs born between 2010 and 2017 were used in the present study resulting in a total of 132,490 records from 55,155 lambs spread over 374 flocks being included for further analysis. An animal linear mixed model was used to derive (co)variance components for the studied traits, for each breed individually. Fixed effects included in the model were contemporary group, dam age at lamb’s birth, dam age at first lambing, a birth type by rearing type of the lamb interaction and a sex by age of the lamb at measurement interaction. Random effects included in the model were the animal additive genetic effect, the dam maternal effect, the litter environment effect and the residual effect. The dam maternal effect applied only to the analysis of early-life weight. Heritability estimates ranged from 0.12 to 0.30 for the two live body weight traits across the three breeds. The two carcass composition traits had heritability estimates ranging from 0.18 to 0.42. Strong positive genetic correlations were observed between all traits analysed. Results from the present study show that genetic variation still exists within breeds for the traits studied indicating that even after over 30 years of genetic selection within the UK they are still amenable to genetic improvement. Furthermore, significant differences in genetic parameters between breeds were observed, especially for carcass composition traits, indicating that genetic evaluations should be calculated separately for each breed.

本研究的主要目的是对纯种英国出生的特克斯，萨福克和Charollais羔羊的两个活体重和两个car体组成性状分别进行遗传分析，以期进行全国范围的评估。考虑的两个活体重特征是早期体重（40-85天龄）和扫描体重（121-180天龄），两个car体组成特征是肌肉深度和脂肪深度。在本研究中仅使用了2010年至2017年之间出生的羔羊的记录，从而将分布在374个鸡群中的55,155只羔羊的132,490条记录包括在内，以供进一步分析。使用动物线性混合模型为每个品种分别推导所研究性状的（共）方差成分。模型中包含的固定效应包括当代群体，羔羊出生时的水坝年龄，初产羔羊的年龄，出生时的羔羊互动类型和出生时的性别。模型中包括的随机效应是动物加性遗传效应，大坝母体效应，产仔环境效应和残留效应。大坝的母性效应仅适用于生命早期体重的分析。三个品种的两个活体重性状的遗传力估计值范围从0.12到0.30。这两个car体组成性状的遗传力估计范围为0.18至0.42。在分析的所有性状之间观察到强的正相关性。本研究的结果表明，所研究性状的品种内仍存在遗传变异，这表明即使在英国进行了30多年的遗传选择后，它们仍然可以进行遗传改良。此外，观察到品种之间的遗传参数存在显着差异，尤其是for体组成性状，这表明应分别计算每个品种的遗传评价。