Influence of sire x herd interaction on the estimation of correlation between direct and maternal genetic effects in Nellore cattle

[摘要] - Sire x herd interactions were studied in 30,789 records of birth (BW) and weaning weight (WW) and weight gain from weaning to 18 months of age (G345) of Nellore cattle born from 1984 to 1994 in twelve farms located in three states of central and southeastern Brazil, with a total of 48.495 animals in pedigree. Sire x herd interaction was considered as a random effect in single trait and two traits animal models using MTDFREML. This effect was important for BW (6% of the phenotypic variance) and it both affected variance and covariance components and, consequently, genetic parameters. The effect was smaller for WW (around 1% of the phenotypic variance), but influenced the estimates of (co) variance components. For G345, Sire x Herd effect was small. Likelihood tests showed that this effect was significant for all traits. This study showed that genetic correlations between direct x maternal effects are close to zero or even positive if sire x herd interaction is fitted in the model, and always negative if it is not.

[学科分类] 兽医学

[关键词] genetic correlation;direct and maternal effects;animal model     IntroduçãoO gado zebu é;hoje;criado nas diferentes regiões do Brasil em vários níveis de manejo