Resumo

DOMINGUEZ-VIVEROS, Joel et al. Genetic parameters for characters associated with the growth curve of Tropicarne cattle. Ecosistemas y recur. agropecuarios [online]. 2017, vol.4, n.10, pp.81-88. ISSN 2007-901X.  https://doi.org/10.19136/era.a4n10.971.

The aim of this study was to estimate genetic parameters for mature weight (MW) and growth rate (GR) derived from the nonlinear Brody model, and analyze the possible genetic relationships between these variables and weaning weight (WW). The information analyzed was MW (kg; n = 994), GR (kg kg-1 month-1, n = 994), and WW adjusted to 240 d (kg; n = 1506); the mean values and standard deviation (±) for MW, GR and WW were 419.1 ± 94.4, 0.0081 ± 0.0039 and 206.8 ± 34.1, respectively; the pedigree was composed of 2504 records. A multivariate analysis was performed (MW, GR and WW) from a mixed model that included as fixed effects the contemporary groups and the covariate age of the cow at calving (linear and quadratic), and as random ones the direct and maternal, maternal permanent environment, and residual genetic effects. Direct and maternal heritability, as well as the genetic correlations between direct (r aa ), maternal (r mm ), and direct with maternal effects (r am ) were estimated. The varied from 0.18 to 0.30, and the from 0.07 to 0.39, indicating that there could be a response to the selection in MW and GR. All genetic correlations were positive in an interval of 0.09 to 0.87, except the r aa between MG and GR (-0.57), this genetic antagonism indicates that individuals with high growth rates do not have the highest mature weight.

Palavras-chave : Genetic correlation; synthetic breed: tropical livestock; nonlinear models; heritability.

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