Schutz M M, Vanraden P M, Wiggans G R
Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350.
J Dairy Sci. 1994 Jan;77(1):284-93. doi: 10.3168/jds.S0022-0302(94)76953-8.
Lactation means of somatic cell scores from sample days were used to estimate the components of variation for additive genetic, permanent environmental, and herd-sire interaction effects. Data included records of 4314 Ayrshire, 7845 Brown Swiss, 18,115 Guernsey, 1,135,752 Holstein, 67,862 Jersey, and 787 Milking Shorthorn cows from across the US. Records were preadjusted for length of lactation. Fixed effects of herd-year, calving age, and calving month were included in animal models for estimation of variance components. Additive genetic estimates from REML relative to a phenotypic variance of 1.00 were .07 for Ayrshires, .07 for Brown Swiss, .11 for Guernseys, .09 for Holsteins, .09 for Jerseys, and .08 for Milking Shorthorns; permanent environmental estimates were .25, .26, .22, .21, .20, and .35; and herdsire interaction estimates were .04, .02, .00, .02, .02, and .01. Effects of calving age were similar for all regions of the US but differed for Jerseys and Holsteins. Effects of calving month were similar for all breeds. Cows calving during summer had the highest lactation means for somatic cell score from sample days. Impact of calving month was greatest in the Southeast.
利用样本日体细胞评分的泌乳方式来估计加性遗传、永久环境和公牛-群体互作效应的变异成分。数据包括来自美国各地的4314头艾尔夏牛、7845头瑞士褐牛、18115头根西牛、1135752头荷斯坦牛、67862头泽西牛和787头乳用短角牛的记录。记录已根据泌乳期长度进行了预调整。群体-年份、产犊年龄和产犊月份的固定效应被纳入动物模型以估计方差成分。相对于表型方差1.00，通过限制最大似然法（REML）得到的加性遗传估计值，艾尔夏牛为0.07，瑞士褐牛为0.07，根西牛为0.11，荷斯坦牛为0.09，泽西牛为0.09，乳用短角牛为0.08；永久环境估计值分别为0.25、0.26、0.22、0.21、0.20和0.35；公牛-群体互作估计值分别为0.04、0.02、0.00、0.02、0.02和0.01。美国所有地区产犊年龄的效应相似，但泽西牛和荷斯坦牛有所不同。所有品种产犊月份的效应相似。夏季产犊的母牛样本日体细胞评分的泌乳均值最高。产犊月份的影响在东南部最大。
