Garrick D J, Pollak E J, Quaas R L, Van Vleck L D
Cornell University, Ithaca, NY 14853.
J Anim Sci. 1989 Oct;67(10):2515-28. doi: 10.2527/jas1989.67102515x.
Phenotypic variances for linear and transformed weight traits were partitioned into residual, direct genetic (D) and maternal genetic (M) components using REML techniques with American Simmental Association data from calves born 1969 to 1985. Variance components were estimated separately from subclasses defined by sex (male, female) and percent Simmental (50, greater than or equal to 75). The model included fixed effects of contemporary group and age-of-dam (less than 3, 3 to 5, greater than 5 yr). Additive relationships among sires and maternal grandsires were included. Results follow for a sire-maternal grandsire model for greater than or equal to 75% Simmental untransformed data based on 143,280 male and 281,805 female weaning weights (WW) representing 4,763 and 7,406 sires, respectively. Female results are bracketed. For computational simplification, 47,650 [30,909] postweaning gain (PW) records were included in the analysis only for 114,404 [182,255] calves with birth weight (BW). Phenotypic standard deviations (kg) were: BW, 4.5 [4.1]; WW, 26.9 [23.2]; and PW, 25.9 [19.9]. Heritabilities were: BWD, .40 [.45]; WWD, .32 [.39]; PWD, .26 [.32]; BWM, .13 [.15]; WWM, .20 [.16]; and PWM, .01 [.01]. These heritabilities are higher than previously used for genetic evaluations in this breed. Moderate and positive correlations .26 to .50, existed between direct effects and were similar for both sexes. Direct and maternal effects on the same trait were correlated negatively: BW, -.45 [-.31]; and WW, -.27 [-.34]. Genetic correlation between BWM and WWM was .53 [.49]. First-cross progeny exhibited less genetic and residual variation and had lower heritabilities than Simmental calves of higher percent. Correlations between sire evaluations on the subsets were consistent with those expected given a perfect genetic correlation between traits for each sex and percent Simmental. Logarithmic transformed records were no more homogeneous than untransformed records.
利用美国西门塔尔协会1969年至1985年出生犊牛的数据，采用限制最大似然法（REML）技术，将线性和转换后的体重性状的表型方差划分为残差、直接遗传（D）和母体遗传（M）成分。方差成分是根据性别（雄性、雌性）和西门塔尔牛百分比（50%、大于或等于75%）定义的亚类分别估算的。模型包括当代组和母牛年龄（小于3岁、3至5岁、大于5岁）的固定效应。考虑了公牛和外祖父的加性亲缘关系。以下是基于143,280头雄性和281,805头雌性断奶体重（WW）的大于或等于75%西门塔尔牛未转换数据的公-外祖父模型的结果，分别代表4,763头和7,406头公牛。雌性结果用括号括起来。为简化计算，仅对114,404头[182,255头]有出生体重（BW）的犊牛的47,650头[30,909头]断奶后增重（PW）记录进行了分析。表型标准差（kg）为：BW，4.5[4.1]；WW，26.9[23.2]；PW，25.9[19.9]。遗传力为：BWD，0.40[0.45]；WWD，0.32[0.39]；PWD，0.26[0.32]；BWM，0.13[0.15]；WWM，0.20[0.16]；PWM，0.01[0.01]。这些遗传力高于该品种以前用于遗传评估的值。直接效应之间存在中等程度的正相关，范围在0.26至0.50之间，且两性相似。同一性状的直接效应和母体效应呈负相关：BW，-0.45[-0.31]；WW，-0.27[-0.34]。BWM和WWM之间的遗传相关为0.53[0.49]。与更高百分比的西门塔尔犊牛相比，一代杂交后代表现出较少的遗传和残差变异，且遗传力较低。各亚组中公牛评估之间的相关性与假设每个性别和西门塔尔牛百分比的性状之间存在完美遗传相关时预期的相关性一致。对数转换后的记录并不比未转换的记录更具同质性。
