Resumo

QUINTERO, Juan C; TRIANA, Juan G; QUIJANO, Jorge H  e  ARBOLEDA, Elkin. Influence of maternal effect in estimating genetic parameters for weaning weight in a beef cattle herd. Rev Colom Cienc Pecua [online]. 2007, vol.20, n.2, pp.117-123. ISSN 0120-0690.

The component of (co)variance and genetic parameters for weaning weight trait in animals of pure (Brahman) or crossbreed (Zebu cattle) breeds were estimated, with the aim to estimate and to compare the genetic parameters and genetic value with or without including the maternal genetic effects by mean of Animal model, using MTDFREML program. Five models were considered including 1) the maternal genetic group, 2) calving, and 3) contemporary group as fixed effects, 4) direct and maternal genetic effects and 5) maternal permanent environmental effects, as random effects, and finally the residual error effect. Direct heritability coefficients varied form median to low (h² _a, 0.10 to 0.29) in all models. Models that included the maternal genetic effect presented the lowest values of maternal heritability (h² _m, 0.07 to 0.17). The genetic correlations between direct and maternal effects were negative and with low magnitude (-0.18 and -0.29). The models were compared between each other using the Maximum Likelihood method (- 2 log L) based on a X2 test, and it gave as result that the best model was the five one (Y = Xb + Z₁a + Z₃m + Z₂ep + e) which included all effects.

Palavras-chave : brahman; direct genetic effects; genetic parameters; maternal genetic effects; weaning weight; zebu.

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