Suzuki M, Van Vleck L D
Department of Animal Science, University of Nebraska, Lincoln 68583-0908.
J Dairy Sci. 1994 Feb;77(2):583-8. doi: 10.3168/jds.S0022-0302(94)76987-3.
Records of the first three lactations of cows were obtained from the file of the Dairy Herd Testing Association in Hokkaido. The data were divided into 10 files containing approximately 24,000 cows each. The derivative-free REML method was used to estimate variances with a repeatability model. The model contained herd-year, calving month, and the linear and quadratic effects of age at calving as fixed effects; additive genetic, permanent environmental, and temporary environmental effects were the random effects. Estimates from the 10 data files wer pooled into a simple arithmetic mean. Empirical standard errors were calculated from the samples. Average estimates of heritability were the same for milk and fat yields (h2 = .30). Heritabilities for protein (h2 = .26) and SNF yields (h2 = .27) are slightly lower than those for milk and fat yields. Estimates of repeatabilities, .52 to .54, are considerably different from those now used for genetic evaluations in Japan.
奶牛前三个泌乳期的记录来自北海道奶牛群测试协会的档案。数据被分成10个文件，每个文件包含约24,000头奶牛。采用无导数REML方法，利用重复性模型估计方差。该模型包含牛群年份、产犊月份以及产犊时年龄的线性和二次效应作为固定效应；加性遗传效应、永久环境效应和临时环境效应为随机效应。将10个数据文件的估计值合并为简单算术平均值。根据样本计算经验标准误差。牛奶和脂肪产量的遗传力平均估计值相同（h2 = 0.30）。蛋白质（h2 = 0.26）和非脂固形物产量（h2 = 0.27）的遗传力略低于牛奶和脂肪产量。重复性估计值在0.52至0.54之间，与日本目前用于遗传评估的值有很大差异。
