Elzo M A, Manrique C, Ossa G, Acosta O
Animal Science Department, University of Florida, Gainesville 32611, USA.
J Anim Sci. 1998 Jun;76(6):1539-49. doi: 10.2527/1998.7661539x.
Intrabreed additive genetic, environmental, and phenotypic variances and covariances for Romosinuano (R) and Zebu (Z), as well as interbreed nonadditive genetic variances and covariances (sire x breed-group-of-dam interactions), for birth weight (BWT), weaning weight (WW), and postweaning gain (GW) were computed using a Romosinuano-Zebu multibreed data set from the Turipaná Experiment Station in Colombia. Covariances were estimated with a sire-maternal grandsire model, using a multibreed REML procedure. The computing algorithm was a generalized expectation-maximization (GEM) algorithm. This algorithm yields no asymptotic standard errors as part of its computations. Because of the small size of the data set (2,546 calves), these REML covariance estimates should be viewed with caution. Estimates of intrabreed heritabilities were similar to the ratios of interbreed nonadditive to phenotypic variances (interactibilities) for direct and maternal effects of the growth traits evaluated in this study. Intrabreed heritability estimates for BWT, WW, and GW direct genetic effects were .16, .09, and .14, for R and .24, .10, and .14 for Z. Corresponding heritability values for maternal effects were .18, .09, and .23 for R and .14, .13, and .07 for Z. Interactibility estimates were .21, .05, and .12, for direct and .26, .04, and .11, for maternal BWT, WW, and GW. Negative correlations between additive maternal weaning weight and direct and maternal postweaning gain, as well as between environmental weaning weight and postweaning gain, suggested that there was compensatory postweaning gain in this herd. Estimates of genetic variation and predictions of expected progeny differences showed that Romosinuano animals competed well against Zebu and RZ crossbred animals under the tropical environmental conditions at Turipaná.
利用来自哥伦比亚图里帕纳实验站的罗姆西努阿诺牛（R）和泽布牛（Z）的多品种数据集，计算了出生体重（BWT）、断奶体重（WW）和断奶后增重（GW）的品种内加性遗传方差、环境方差和表型方差及协方差，以及品种间非加性遗传方差和协方差（父本×母本品种组互作）。协方差采用父本-母本祖父模型，通过多品种限制最大似然法（REML）程序进行估计。计算算法为广义期望最大化（GEM）算法。该算法在计算过程中不产生渐近标准误差。由于数据集规模较小（2546头犊牛），这些REML协方差估计值应谨慎看待。本研究中评估的生长性状直接和母体效应的品种内遗传力估计值与品种间非加性与表型方差的比率（互作性）相似。罗姆西努阿诺牛BWT、WW和GW直接遗传效应的品种内遗传力估计值分别为0.16、0.09和0.14，泽布牛分别为0.24、0.10和0.14。母体效应的相应遗传力值，罗姆西努阿诺牛分别为0.18、0.09和0.23，泽布牛分别为0.14、0.13和0.07。BWT、WW和GW直接效应的互作性估计值分别为0.21、0.05和0.12，母体效应分别为0.26、0.04和0.11。加性母体断奶体重与直接和母体断奶后增重之间，以及环境断奶体重与断奶后增重之间的负相关表明，该牛群存在断奶后补偿性增重。遗传变异估计值和预期后代差异预测表明，在图里帕纳的热带环境条件下，罗姆西努阿诺牛与泽布牛及罗姆西努阿诺牛-泽布牛杂交牛竞争良好。
