Meyer K, Hammond K, Mackinnon M J, Parnell P F
University of New England, Armidale, NSW, Australia.
J Anim Sci. 1991 Sep;69(9):3533-43. doi: 10.2527/1991.6993533x.
Estimates of covariance components between scrotal circumference, serving capacity, days to calving, and yearling and final weight were obtained for Hereford, Angus, and Zebu cross cattle in temperate and tropical Australia. Analyses were carried out by REML employing a derivative-free algorithm and fitting bivariate animal models. Aspects of modeling and computational requirements related to the use of this method are discussed. Estimates of heritabilities agreed closely with those from univariate analyses, being low for female reproductive performance and moderate to high for male reproduction and growth. Estimates of genetic correlation between male and female fertility traits were low but favorable, being -.25, -.28, and -.41 between scrotal circumference and days to calving for Herefords, Angus, and Zebu crosses, respectively. Genetic correlations between male reproductive traits and weights ranged from .24 to .52 for the temperate breeds and were higher (.65 to .69) for Zebu crosses. Phenotypic correlations between scrotal circumference and weights were similar for all breeds, ranging from .32 to .47, whereas serving capacity and weights were phenotypically unrelated. Estimates of correlations between days to calving and weights were less consistent. Phenotypically, there was little association between the two traits. Genetic correlations for Zebu crosses were negative and low to moderate (-.36 to -.66) and estimates for Angus were close to zero.
在澳大利亚温带和热带地区，对赫里福德牛、安格斯牛和瘤牛杂交牛的阴囊周长、配种能力、产犊天数以及一岁龄和成年体重之间的协方差成分进行了估计。采用无导数算法并拟合双变量动物模型，通过限制最大似然法（REML）进行分析。讨论了与该方法使用相关的建模和计算要求方面的问题。遗传力估计值与单变量分析的结果非常接近，雌性繁殖性能的遗传力较低，而雄性繁殖和生长的遗传力为中等至高。雄性和雌性繁殖性状之间的遗传相关性较低但呈正向，赫里福德牛、安格斯牛和瘤牛杂交种的阴囊周长与产犊天数之间的遗传相关性分别为-0.25、-0.28和-0.41。温带品种的雄性繁殖性状与体重之间的遗传相关性在0.24至0.52之间，瘤牛杂交种的遗传相关性更高（0.65至0.69）。所有品种的阴囊周长与体重之间的表型相关性相似，范围在0.32至0.47之间，而配种能力与体重在表型上不相关。产犊天数与体重之间的相关性估计不太一致。在表型上，这两个性状之间几乎没有关联。瘤牛杂交种的遗传相关性为负且低至中等（-0.36至-0.66），安格斯牛的估计值接近零。
