The objective of this study was to determine whether response to selection for carcass weight (CW), conformation (CC) and fat (CF), and the association between heterosis and carcass performance varied by herd environment in cattle. Following edits, carcass information was available for 4,616,761 cattle, of which the majority were some crossbred combination of the following breeds: Angus, Aubrac, Belgian Blue, Blonde d’Aquitaine, Charolais, Hereford, Holstein-Friesian, Jersey, Limousin, Saler, Shorthorn and Simmental. Herd environment was defined separately for each carcass trait using herd solutions outputted from carcass trait genetic evaluations. A total of 3,859 herds were stratified, for each trait, into one of five strata based on their corresponding percentile herd solution rank, with the response to selection and the effect of heterosis then estimated within each stratum. The response in CW and CC from selection on the respective estimated breeding values (EBV) increased between the lowest (0.71 kg and 0.89 CC score increase per unit increase in the respective EBV) and highest (0.99 kg and 1.25 CC score increase per unit increase in the respective EBV) corresponding herd stratum. The response in CF from selection on CF EBV, however, reduced between the lowest and highest CF herd stratum (respective increases of 0.93 and 0.83 CF scores per unit increase in CF EBV). In addition, the effect of a unit increase in heterosis coefficient on CW, CC and CF also varied by herd stratum. Furthermore, results (i.e. the area under relative operating characteristic curves) from the present study demonstrated that the response to selection and heterosis effects estimated for the different herd stratum can be used, along with EBVs and the herd solutions themselves, to improve the accuracy of phenotypic predictions. Results from the present study could help producers to make more informed breeding decisions that are bespoke to their herd.

中文翻译：

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来自遗传评估的畜群解决方案可用作重新调整牛遗传潜力预期表达的工具

本研究的目的是确定对屠体重量 (CW)、构象 (CC) 和脂肪 (CF) 选择的反应，以及杂种优势与屠体性能之间的关联是否因牛群环境而异。经过编辑，可获得 4,616,761 头牛的胴体信息，其中大部分是以下品种的杂交组合：安格斯、奥布拉克、比利时蓝、金发阿基坦、夏洛来、赫里福德、荷斯坦-弗里斯兰、泽西、利穆赞、萨勒、短角牛和西门塔尔。使用从屠体性状遗传评估输出的畜群解决方案，为每个畜体性状单独定义畜群环境。对于每个性状，共有 3,859 个牛群根据其相应的百分比牛群解决方案等级分为五个层之一，然后在每个层内估计对选择的反应和杂种优势的影响。CW 和 CC 对各自估计育种值 (EBV) 的选择响应在最低（相应 EBV 的每单位增加 0.71 kg 和 0.89 CC 得分增加）和最高（每单位增加 0.99 kg 和 1.25 CC 得分增加）之间增加在各自的 EBV) 对应的群体层。然而，CF EBV 选择对 CF 的响应在最低和最高 CF 群体层之间降低（CF EBV 的每单位增加分别增加 0.93 和 0.83 CF 分数）。此外，杂种优势系数增加一个单位对CW、CC和CF的影响也因畜群层次而异。此外，结果（即 相对操作特征曲线下的面积）从本研究表明，可以使用对不同畜群层估计的选择和杂种优势效应的响应，连同 EBV 和畜群解决方案本身，以提高表型预测的准确性。本研究的结果可以帮助生产者做出更明智的育种决定，这些决定是为他们的牛群定制的。