Genetic parameters and phenotypic and genetic trends for weight at weaning and visual scores during this phase estimated for Angus-Nellore crossbred young bulls

Revista Brasileira de Zootecnia

Ronyere Olegário De Araújo²  Paulo Roberto Nogara Rorato¹  Tomás Weber²  Dionéia Magda Everling²  Jader Silva Lopes¹  Mariana De Almeida Dornelles² 

[1],UFSM Programa de Pós-Graduação em Zootecnia Santa Maria RS ,Brasil

关键词: beef cattle;    cross-breeding;    genetic evaluation;    genetic progress;    morphologic evaluation;    avaliação genética;    avaliação morfológica;    bovinos de corte;    cruzamento;    progresso genético;   

DOI  :  10.1590/S1516-35982010001100012

来源: SciELO

【 摘 要 】

Genetic parameters and genetic and phenotypic trends were estimated for weight at weaning (WW) and visual scores (VS) of conformation (C), precocity (P), musculature (M) and navel (N) for Angus × Nellore crossbred calves. It was used 39,676 records from pre-weaning phase of animals born from 1992 to 2002 in mid-western, southeastern and southern Brazil. The components of covariance were estimated using REML, in animal model, considering as random the maternal and direct additive genetic effects, and as fixed, the effects of contemporaneous group, the genetic group of the animal and of the cow, and as covariates the age of the calf at weaning and the age of the cow at calving, both on days and with linear and quadratic effects, besides direct (DH) and maternal heterosis (MH), both with only the linear effect. Estimates of direct and maternal heritability were 0.30 and 0.19, respectively, for WW, whereas VSs ranged from 0.16 to 0.20 and from 0.09 to 0.16, which indicates the possibility to obtain genetic gain through selection. It is expected answer correlated to C, P and for M when selection is practiced for weight at weaning is expected, as well as for P and M when selection is practiced for C. The direct and maternal genetic trends for WW (g/year) and for C, P, M and N (points/year) were: 221.0 and -312.0; 0.0022 and 0.00003; 0.0010 and 0.0001; 0.0013 and -0.0008; 0.0010 and 0.00009, respectively, while the phenotypic were: -685.2; -0.0102; -0.0219; -0.0256 and -0.0453, which highlights the need to adopt criteria for identifying young bulls of higher genetic value for WW and VSs.

【 授权许可】

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