Barkhouse K L, Van Vleck L D, Cundiff L V
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA.
J Anim Sci. 1998 Sep;76(9):2279-86. doi: 10.2527/1998.7692279x.
Data were weights of F1 calves and weaning weights of top-cross progeny from sires and maternal grandsires of 13 breeds. Three analyses were performed on each trait to obtain estimates and standard errors of breed effects needed to calculate across-breed EPD and accuracies. Model (R) for records of F1 progeny contained fixed effects for birth year and date of birth, sex, age and breed of dam, and breed of sire, and a random residual effect. The second analysis included random effects for sires (RS), and the third analysis included random effects for sires and dams (RSD). In maternal analysis of top-cross progeny, model (Rm) contained fixed effects for cycle of experiment, age of dam, year of birth, sex, breeds of maternal grandam and grandsire, and breed of sire, and a random residual effect. In addition, the second and third analyses fit random effects for maternal grandsires (RSm) and for maternal grandsires and daughters of maternal grandsires (RSDm). Estimates of breed of sire effects changed only slightly for different models. Total variance increased in RSD and RS relative to R. Standard errors of breed of sire comparisons were underestimated with Model R, compared to Models RS and RSD. Standard errors of other contrasts were generally not affected. Variance components, breed effects, and standard errors followed patterns for Rm, RSm, and RSDm similar to those for R, RS, and RSD. Ignoring random variation due to sires and dams underestimated standard errors of breed of sire comparisons.
数据为13个品种的F1代犊牛体重以及父系和母系祖父的顶级杂交后代的断奶体重。对每个性状进行了三次分析，以获得计算跨品种预期子代差异（EPD）和准确性所需的品种效应估计值和标准误。F1代后代记录的模型（R）包含出生年份、出生日期、性别、母畜年龄和品种以及父系品种的固定效应，以及随机残差效应。第二次分析包括父系的随机效应（RS），第三次分析包括父系和母系的随机效应（RSD）。在顶级杂交后代的母系分析中，模型（Rm）包含实验周期、母畜年龄、出生年份、性别、母系祖母和祖父的品种以及父系品种的固定效应，以及随机残差效应。此外，第二次和第三次分析拟合了母系祖父（RSm）以及母系祖父和母系祖父女儿（RSDm）的随机效应。不同模型下父系品种效应的估计值变化不大。与模型R相比，RSD和RS中的总方差增加。与模型RS和RSD相比，模型R低估了父系品种比较的标准误。其他对比的标准误一般不受影响。方差分量、品种效应和标准误在Rm、RSm和RSDm中的模式与R、RS和RSD中的模式相似。忽略父系和母系的随机变异会低估父系品种比较的标准误。
