Jairath L K, Hayes J F, Cue R I
Department of Animal Science, Macdonald Campus of McGill University, Ste. Anne de Bellevue, PQ, Canada.
J Dairy Sci. 1995 Feb;78(2):438-48. doi: 10.3168/jds.S0022-0302(95)76653-X.
Data on 82,835 Holstein cows, daughters of 703 sires and with first calvings from 1979 to 1984 in 2384 herds enrolled in Quebec Dairy Herd Analysis Service, were analyzed for relationships of first lactation traits with traits for partial and total lifetime performance using multitrait REML methodology and a linear mixed model. Effects of herd-year-season, age at first calving, and proven sires were considered to be fixed, and effects of young sires and residuals were considered to be random. All known additive genetic relationships among sires were accounted for in construction of the relationship matrix. Individual lactation records were precorrected for the fixed effect of year and month of calving before lifetime totals were calculated. Each cow was given at least a 5-yr opportunity for production. All genetic and phenotypic correlations were positive except correlations of first lactation percentage traits. Correlations with partial lifetime performance were highest. Genetically, first lactation milk yield was highly correlated with most measures of lifetime performance, .64 to .92; correlations with measures of longevity were relatively smaller. Given high positive genetic correlations, selection singly on first lactation milk yield will improve all measures of lifetime performance; however, some measure of longevity should be considered in selection programs of dairy cattle.
对魁北克奶牛群分析服务中登记的2384个牛群里82835头荷斯坦奶牛的数据进行了分析，这些奶牛是703头公牛的女儿，首次产犊时间为1979年至1984年。使用多性状REML方法和线性混合模型，分析了首次泌乳性状与部分和整个生命周期生产性能性状之间的关系。牛群-年份-季节、首次产犊年龄和经证实的公牛的影响被视为固定效应，年轻公牛和残差的影响被视为随机效应。在构建关系矩阵时考虑了公牛之间所有已知的加性遗传关系。在计算生命周期总数之前，对个体泌乳记录进行了产犊年份和月份固定效应的预校正。每头奶牛至少有5年的生产机会。除首次泌乳百分比性状的相关性外，所有遗传和表型相关性均为正。与部分生命周期生产性能的相关性最高。从遗传学角度来看，首次泌乳产奶量与大多数生命周期生产性能指标高度相关，为0.64至0.92；与长寿指标的相关性相对较小。鉴于存在高度正遗传相关性，仅选择首次泌乳产奶量将改善所有生命周期生产性能指标；然而，在奶牛选择计划中应考虑一些长寿指标。
