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

• Published in: Revista brasileira de zootecnia 2010-11, Vol.39 (11), p.2398-2408
• Main Authors: Araújo, Ronyere Olegário de(UFSM Programa de Pós-Graduação em Zootecnia), Rorato, Paulo Roberto Nogara(UFSM CCR Departamento de Zootecnia), Weber, Tomás(UFSM Programa de Pós-Graduação em Zootecnia), Everling, Dionéia Magda(UFSM Programa de Pós-Graduação em Zootecnia), Lopes, Jader Silva(Sadia S/A CIEx Agropecuário), Dornelles, Mariana de Almeida(UFSM Programa de Pós-Graduação em Zootecnia)
• Format: Article
• Language: English
• Subjects: AGRICULTURE, DAIRY & ANIMAL SCIENCE; avaliação genética; avaliação morfológica; beef cattle; bovinos de corte; cross-breeding; cruzamento; genetic evaluation; genetic progress; morphologic evaluation; progresso genético; VETERINARY SCIENCES
• ISSN: 1516-3598; 1806-9290; 1806-9290; 1516-3598
• DOI: 10.1590/S1516-35982010001100012

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. Foram estimados parâmetros genéticos e tendências genéticas e fenotípicas para peso a desmama (PD) e para os escores visuais (EVs) de conformação (C), precocidade (P), musculatura (M) e umbigo (U), para bezerros produtos do cruzamento entre as raças Angus e Nelore. Foram utilizados 39.676 registros da fase pré-desmama, de animais nascidos entre os anos de 1992 e 2002, nas regiões Centro-oeste, Sudeste e Sul do Brasil. Os componentes de (co)variâncias foram estimados utilizando-se o REML, em modelo animal, considerando como aleatórios, os efeitos genéticos aditivos diretos e maternos e, como fixos, os efeitos de grupo de contemporâneos, grupo genético do animal e da vaca e, como covariáveis a idade do bezerro a desmama, a idade da vaca ao parto, ambas em dias e com efeitos linear e quadrático, além da heterose direta (HD) e a heterose materna (HM), ambas somente com efeito linear.