57º Congresso Brasileiro de Genética
Resumos do 57º Congresso Brasileiro de Genética • 30 de agosto a 2 de setembro de 2011
Centro de Convenções do Hotel Monte Real Resort • Águas de Lindóia • SP • Brasil
www.sbg.org.br - ISBN 978-85-89109-06-2
74
Genetic parameters for categorical traits in a
composite beef cattle population (Bos taurus x
Bos indicus)
Salvian, M1; Petrini, J2; Zampar, A2; Eler, JP3; Ferraz, JBS3; Mourão, GB3
Graduação em Engenharia Agronômica, Escola Superior de Agricultura “Luiz de Queiroz”, USP, Piracicaba, SP, 2
Programa de Pós-Graduação em “Ciência Animal e Pastagens”, Escola Superior de Agricultura “Luiz de Queiroz”, USP,
Piracicaba, SP, 3 Professor Associado do Departamento de Zootecnia, Escola Superior de Agricultura “Luiz de Queiroz”,
USP, Piracicaba, SP, 4 Faculdade de Zootecnia e Engenharia de Alimentos, USP, Pirassununga, SP
[email protected]
1
Keywords: Conformation score, Genetic correlation, Heritability, Muscle score, Precocity score, Visual scores
Recently, animal breeding programs have a special interest in the visual scores traits, mainly due to their easily measurement and high correlation with production, carcass and meat quality traits. The inclusion of conformation, precocity
and muscle scores as selection criterions in sire evaluation permits the identification of superior animals in relation
to development and, simultaneously, with better morphological conformation and earlier finishing. Although several
studies had estimated genetic parameters for these traits, researchers involving categorical traits in composite populations are still rare. Therefore, the aim of this study was estimate heritability coefficients and genetic correlations
for visual scores traits in a multi-breed population. Data of the composite bovine Montana Tropical born between
1994 and 2009 were used. Genetic parameters for conformation (CONF; n=2,877), precocity (PREC; n=1,748) and
muscle (MUSC; n=76,953) scores, were estimated through restricted maximum likelihood method under an animal
model, using the software VCE. The genetic model included the fixed effects of contemporary groups and class of
age of the dam; the covariates of direct and maternal additive and non-additive genetic effects, Julian day effect and
age at measurement effect; and the random genetic effects of animal and dam. Genetic correlations were obtained by
bivariate analysis between the categorical traits, and these and production and reproductive traits. Heritability coefficients were 0.15 for CONF and 0.21 for MUSC. The low estimate for PREC (h2=0.05) is probably due to the number
of observations and contemporary groups (n=33), which do not permitted a good estimation of genetic and environmental effects. The maternal effect was only important for CONF (hm2 = 0.09), mainly because of the age of the
animals at measurement, around 365 days. Correlations between the visual scores were high (r=0.66 to 0.91), which
indicates common genetic control for these traits. The moderate magnitude of the heritability estimates suggests that
it is possible to improve the conformation and muscle scores through animal selection. Despite the low heritability,
the high correlations with the other traits permit to obtain genetic gain in precocity employing indirect selection.
Financial support: CAPES, CNPq and FAPESP.