Modeling and estimation of genetic parameters for weights from birth to selection age (378 Days) of Nellore males

Revista Brasileira de Zootecnia

Razook, Alexander George²  Mercadante, Maria Eugênia Zerlotti²  Alencar, Maurício Mello de¹  Cyrillo, Joslaine Noely dos Santos Gonçalves²  Figueiredo, Leopoldo Andrade de² 

[1] Embrapa Pecuária Sudeste, São Carlos;Instituto de Zootecnia, Sertãozinho

关键词: beef cattle;    heritability;    maternal effects;    repeated records;    subsequent ages;    variance components    IntroduçãoA decomposição dos componentes da variância fenotípica em variância genética e ambiental é baseada no princípio de que a semelhança fenotípica entre parentes fornece informações a respeito do grau de diferenciação genética entre eles;   

DOI  :  10.1590/S1516-35982004000600007

学科分类：兽医学

来源: Universidade Federal de Vicosa

【 摘 要 】

Genetic parameters for weights (17, 942 records), obtained in intervals of 60 days, from the birth to selection (378 days of age), of 2,582 males of the Nellore breed was estimated in univariate analyses by the Maximum Restricted Likelihood method. The models of analysis models included the fixed effects of contemporary groups, month of birth, mother age and age when the weights were collected as covariate. Three models differing in random effects were tested: the model 1 (M1) was adjusted for the direct and maternal addictive genetic effects and maternal permanent environment; in model 2 (M2) the maternal genetic effect was excluded; and the model 3 (M3) was only adjusted for the direct addictive genetic effect. The test of likelihood (LRT) detected significant differences, for all the ages, of M2 and M1 in relation to the simple model (M3), evidencing the importance of the maternal effects. Except for the birth weight (0.40), low values (0.05 to 0.12) of h2 were found for M1 and M2 until 8 months of age and, after this period, reasonable increase could be observed, reaching 0.28 until 13 months of age. The estimates of the total variance fraction, due to the effect of maternal permanent environment, were high and practically became unaffected between the models 1 and 2. Maternal effects, not necessarily decomposed (in genetic addictive and permanent environment), affected the Nellore males growth. Models that contemplate maternal effects, besides the genetic addictive direct effects, are more realistic to describe the trajectory of the variances in the initial phases of growth of Nelore male calves.

【 授权许可】

CC BY-NC