Department of Animal Sciences, University of Wisconsin, Madison 53706.
Department of Animal Sciences, University of Wisconsin, Madison 53706; Department of Dairy Science, University of Wisconsin, Madison 53706.
J Dairy Sci. 2018 May;101(5):4307-4311. doi: 10.3168/jds.2017-13660. Epub 2018 Feb 15.
Multiple births or twinning in cattle is a naturally occurring reproductive phenomenon. For dairy cattle, twinning is considered a detrimental trait as it can be harmful to cow and calf as well as costly to the producer. The objective of this study was to examine recent US calving records for the Holstein breed to determine a current estimate of heritability for twinning rate along with effects of season and parity. Two models were used in this study: a linear sire model and a binary threshold-logit sire model. Both were mixed models considering fixed effects and random effects. Analyses were conducted using a restricted maximum likelihood method. Heritability estimates were 0.0192 ± 0.0009 and 0.1420 ± 0.0069 for the linear and threshold models, respectively. Repeatabilities from the linear and threshold-logit models were 0.0443 ± 0.0012 and 0.2310 ± 0.0072, respectively. The nonzero estimates of heritability indicate the potential to select against this trait for genetic improvement of Holstein cattle.
牛的多胎或双胞胎是一种自然发生的生殖现象。对于奶牛来说，双胞胎是一种有害的特征，因为它可能对奶牛和小牛都有害，而且对生产者来说成本也很高。本研究的目的是检查最近美国荷斯坦牛的产犊记录，以确定双胞胎率的当前遗传力估计值，以及季节和胎次的影响。本研究使用了两种模型：线性 sire 模型和二元阈值逻辑 sire 模型。这两种模型都是混合模型，考虑了固定效应和随机效应。分析采用限制最大似然法进行。线性和阈值模型的遗传力估计值分别为 0.0192 ± 0.0009 和 0.1420 ± 0.0069。线性和阈值-logit 模型的重复率分别为 0.0443 ± 0.0012 和 0.2310 ± 0.0072。遗传力的非零估计表明，有可能选择反对这种特征，以改善荷斯坦牛的遗传。
