SIRE– MATERNAL GRANDSIRE INTERACTION ON (CO)VARIANCE ESTIMATIONS, AND GENETIC TREND OF PRE-WEANING GROWTH TRAITS OF NELLORE CATTLE

• Autor(a) principal: de Los Reyes, Arcadio
• Data de Publicação: 2007
• Outros Autores: Elzo, Mauricio A. A., Sanches, Ana Christina, Lôbo, Raysildo B., Bezerra, Luiz A. F.
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Ciência animal brasileira (Online)
• Texto Completo: https://revistas.ufg.br/vet/article/view/857

Adjusted weights at 120 (P120) and 240 (P240) days of age from 8,084 Nellore calves of both sexes were used to obtain estimate of (co)variance components and predictions of breeding values. Calves were born between 1987 and 1997 and raised on pasture in 31 herds. The complete mixed model for each trait included the fixed effects of contemporary group (herd-year-season-sex-management group) and six cow age at calving classes (2, 3, 4, 5, 6 to 9, and 10 years and older cows), and random additive genetic effects of animal (direct and maternal), maternal permanent environmental, sire x maternal grandsire interaction (PAM) and residual. Inclusion of PAM interaction explained between 2.8 and 3.1 % of the phenotypic variance, and caused a reduction in direct and maternal variances and an increase in direct-maternal covariances. Direct heritabilities diminished from 0.24 to 0.20 (P120), and from 0.24 to 0.19 (P240). Corresponding maternal heritabilities decreased from 0.17 to 0.13 and from 0.20 to 0.16. Direct-maternal genetic correlations increased from 0.05 to 0.29 (P120), and from -0.12 to 0.01 (P240), indicating no antagonism. Figures of annual breeding value means showed scarce or any progress during the analyzed period, particularly on maternal ability. Intensive use of few sires could be a major factor contributing to these results. The PAM interaction effect and the genetic trend must be investigated further on a database including recent information. KEY WORDS: (Co)variances, genetic trend, sire–maternal grandisre interaction.