Martínez-González Juan Carlos, García-Esquivel Francisco Javier, Parra-Bracamonte Gaspar Manuel, Castillo-Juárez Héctor, Cienfuegos-Rivas Eugenia Guadalupe
Universidad Autónoma de Tamaulipas, Ciudad Victoria, 87030, Tamaulipas, Mexico.
Trop Anim Health Prod. 2010 Jun;42(5):887-92. doi: 10.1007/s11250-009-9502-9. Epub 2009 Dec 1.
The aim of this study was to estimate genetic parameters for growth traits in Mexican Nellore cattle. A univariate animal model was used to estimate (co)variance components and genetic parameters. The traits evaluated were birth weight (BW), weaning weight (WW), and yearling weight (YW). Models used included the fixed effects of contemporary groups (herd, sex, year, and season of birth) and age of dam (linear and quadratic) as a covariate. They also included the animal, dam, and residual as random effects. Phenotypic means (SD) for BW, WW, and YW were 31.4 (1.6), 175 (32), and 333 (70) kg, respectively. Direct heritability, maternal heritability, and the genetic correlation between additive direct and maternal effects were 0.59, 0.17, and -0.90 for BW; 0.29, 0.17, and -0.90 for WW; and 0.24, 0.15, and -0.86 for YW, respectively. The results showed moderate direct and maternal heritabilities for the studied traits. The genetic correlations between direct and maternal effects were negative and high for all the traits indicating important tradeoffs between direct and maternal effects. There are significant possibilities for genetic progress for the growth traits studied if they are included in a breeding program considering these associations.
本研究的目的是估计墨西哥内洛尔牛生长性状的遗传参数。使用单变量动物模型来估计（协）方差分量和遗传参数。评估的性状包括出生体重（BW）、断奶体重（WW）和周岁体重（YW）。所使用的模型包括当代组（牛群、性别、年份和出生季节）的固定效应以及作为协变量的母牛年龄（线性和二次项）。它们还包括动物、母牛和残差作为随机效应。BW、WW和YW的表型均值（标准差）分别为31.4（1.6）、175（32）和333（70）千克。BW的直接遗传力、母体遗传力以及加性直接效应和母体效应之间的遗传相关性分别为0.59、0.17和 -0.90；WW的分别为0.29、0.17和 -0.90；YW的分别为0.24、0.15和 -0.86。结果表明，所研究性状的直接和母体遗传力适中。所有性状的直接效应和母体效应之间的遗传相关性均为负且较高，表明直接效应和母体效应之间存在重要的权衡。如果将所研究的生长性状纳入考虑这些关联的育种计划中，则实现遗传进展的可能性很大。
