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. 1994 Jan;77(1):303-12. doi: 10.3168/jds.S0022-0302(94)76955-1.
Data on 82,835 Holstein cows, daughters of 703 sires and with first calving from September 1979 to December 1984 from 2384 herds enrolled in the Quebec Dairy Herd Analysis Service, were used to estimate genetic and phenotypic parameters of partial and total lifetime performance traits with REML. The model included herd-year-season of first calving, age at first calving, and proven sires as fixed effects and young sires and residuals as random effects. Individual lactation records were precorrected for year-month of calving before lifetime totals were calculated. Only cows with at least 5 yr of opportunity for production were analyzed. The ranges of heritability estimates were .11 to .13 for lifetime production and profit, .07 to .09 for measures of longevity, and .28 to .32 for yield per day of productive life. Correlations among total lifetime yield and profit traits and among measures of longevity were > or = .93. Genetic and phenotypic correlations, respectively, of early partial (two parities total) with total life-time yield and profit and longevity traits ranged from .81 to .94 and .66 to .78. Selection on early performance seems to be desirable and, given the high positive genetic correlations, should increase both lifetime yield and longevity.
对来自魁北克奶牛群分析服务中心登记的2384个牛群、出生于1979年9月至1984年12月、首次产犊的82835头荷斯坦奶牛的数据进行分析，这些奶牛是703头公牛的后代，利用REML估计部分和整个生命周期生产性状的遗传和表型参数。模型包括首次产犊的牛群-年份-季节、首次产犊年龄和经证实的公牛作为固定效应，年轻公牛和残差作为随机效应。在计算整个生命周期总数之前，对个体泌乳记录按产犊的年份-月份进行了预先校正。仅分析了至少有5年生产机会的奶牛。终身产量和利润估计的遗传力范围为0.11至0.13，长寿指标的遗传力范围为0.07至0.09，生产寿命每天产量的遗传力范围为0.28至0.32。终身总产量和利润性状之间以及长寿指标之间的相关性≥0.93。早期部分（总共两胎）与终身总产量、利润和长寿性状的遗传和表型相关性分别为0.81至0.94和0.66至0.78。对早期性能进行选择似乎是可取的，鉴于高度正遗传相关性，应能提高终身产量和长寿。
