Animal and Grassland Research and Innovation Centre, Teagasc, Moorepark, Fermoy, Co. Cork, P61 C996, Ireland; Department of Biological Sciences, Munster Technological University, Bishopstown Campus, Cork, T12 VN56, Ireland.
Department of Biological Sciences, Munster Technological University, Bishopstown Campus, Cork, T12 VN56, Ireland.
J Dairy Sci. 2024 Oct;107(10):8150-8156. doi: 10.3168/jds.2023-24633. Epub 2024 May 31.
As the proportion of prime carcasses originating from dairy herds increases, the focus is shifting to the beef merit of the progeny from dairy herds. Several dairy cow total merit indexes include a negative weight on measures of cow size. However, there is a lack of knowledge on the effect of genetic selection, solely for lighter or smaller-sized dairy cows, on the beef performance of their progeny. Therefore, the objective of this study was to quantify the genetic correlations among cow size traits (i.e., cow BW, cow carcass weight [CW]), cow BCS, cow carcass conformation (CC), and cow carcass fat cover (CF), as well as the correlations between these cow traits and a series of beef performance slaughter-related traits (i.e., CW, CC, CF, and age at slaughter [AS]) in their progeny. After data editing, there were 52,950 cow BW and BCS records, along with 57,509 cow carcass traits (i.e., CW, CC, and CF); carcass records from 346,350 prime animals along with AS records from 316,073 prime animals were also used. Heritability estimates ranged from moderate to high (0.18-0.62) for all cow and prime animal traits. The same carcass trait in cows and prime animals were strongly genetically correlated with each other (0.76-0.85), implying that they are influenced by very similar genomic variants. Selecting exclusively for cows with higher BCS (i.e., fatter) will, on average, produce more conformed prime animal carcasses, owing to a moderate genetic correlation (0.30) between both traits. Genetic correlations revealed that selecting exclusively for lighter BW or CW cows will, on average, result in lighter prime animal carcasses of poor CC, while also delaying slaughter age. Nonetheless, selective breeding through total merit indexes should be successful in breeding for smaller dairy cows and desirable prime animal carcass traits concurrently, because of the nonunity genetic correlations between the cow and prime animal traits; this will help to achieve a more ethical, environmentally sustainable, and economically viable dairy-beef industry.
随着源自奶牛群的优质胴体比例增加，人们的关注点逐渐转向奶牛群后代的牛肉质量。几个奶牛综合质量指数包括对奶牛体型的负向权重。然而，对于单纯为了选择体型更小、体重更轻的奶牛进行遗传选育，对其后代牛肉性能的影响，我们知之甚少。因此，本研究的目的是量化奶牛体型性状（即奶牛体重、牛胴体重[CW]）、奶牛体况评分（BCS）、奶牛体躯结构（CC）和奶牛体躯脂肪覆盖（CF）之间的遗传相关性，以及这些奶牛性状与一系列牛肉性能屠宰相关性状（即 CW、CC、CF 和屠宰年龄[AS]）之间的相关性在其后代中。经过数据编辑，有 52950 个奶牛 BW 和 BCS 记录，以及 57509 个奶牛胴体性状（即 CW、CC 和 CF）；还使用了 346350 个优质动物的胴体记录和 316073 个优质动物的 AS 记录。所有奶牛和优质动物性状的遗传力估计值从中等偏高（0.18-0.62）。奶牛和优质动物的同一胴体性状之间具有很强的遗传相关性（0.76-0.85），这表明它们受非常相似的基因组变异的影响。专门选择体况评分较高（即更胖）的奶牛，通常会产生更多符合要求的优质动物胴体，因为这两个性状之间存在中等遗传相关性（0.30）。遗传相关性表明，专门选择体重较轻或 CW 奶牛，通常会导致优质动物胴体较轻、CC 较差，同时也会延迟屠宰年龄。然而，通过综合质量指数进行选择性繁殖，应该能够成功地同时培育体型更小的奶牛和理想的优质动物胴体性状，因为奶牛和优质动物的性状之间存在非统一的遗传相关性；这将有助于实现更符合道德规范、更具环境可持续性和更具经济可行性的奶牛-牛肉产业。
