Influência da Interação Touro x Rebanho na Estimação da Correlação entre Efeitos Genéticos Direto e Materno em Bovinos da Raça Nelore

Abstract

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.