| Autor: |
Everling DM; Departamento de Zootecnia, Universidade Federal de Santa Maria, Santa Maria, RS, Brasil., Bresolin T; Departamento de Zootecnia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista, Jaboticabal, SP, Brasil t_bresolin@zootecnista.com.br., Rorato PR; Departamento de Zootecnia, Universidade Federal de Santa Maria, Santa Maria, RS, Brasil., Araujo RO; Programa de Pós-Graduação em Ciência Animal, Universidade Nacional de Brasília, Campus Universitário Darcy Ribeiro, Brasília, DF, Brasil., Boligon AA; Departamento de Zootecnia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista, Jaboticabal, SP, Brasil., Weber T; Departamento de Zootecnia, Universidade Federal de Santa Maria, Santa Maria, RS, Brasil., Dornelles MA; Departamento de Zootecnia, Universidade Federal de Santa Maria, Santa Maria, RS, Brasil., Campos LT; Associação Nacional de Criadores Herd Book Collares, Pelotas, RS, Brasil. |
| Abstrakt: |
Finishing precocity visual score selection was adopted to estimate the time from birth to reach slaughter age. This study estimated (co)variance components and genetic correlations for the finishing precocity score at weaning (WP) and yearling (YP) stages by using daily weight gain (BWG = from birth to weaning; WYG = from weaning to yearling) and speed of weight gain (BWR = from birth to weaning; WYR = from weaning to yearling) as support for a genetic evaluation program for Angus beef cattle. Genetic parameters were estimated using Bayesian inference, considering multi-trait analysis and assuming a nonlinear model for WP and YP and linear model for all other traits. Direct heritability estimates were 0.17 (WP), 0.19 (YP), 0.15 (BWG), 0.16 (WYG), 0.15 (BWR), and 0.16 (WYR). The genetic correlation between the finishing precocity score at two ages (weaning and yearling) was 0.61. Positive and moderate genetic correlations were obtained between WP and BWG (0.47) and WP and BWR (0.46). In contrast, negative and low genetic associations were estimated between WP and yearling growth traits (-0.16, WYG; -0.15, WYR). Genetic correlations between YP and other traits were positive 0.29 (BWG), 0.28 (BWR), 0.48 (WYG), and 0.47 (WYR). The selection response for the finishing precocity score at weaning and yearling ages would be low. Selection to increase WP and YP should result in favorable genetic changes in daily weight gains as a correlated response. Therefore, to obtain animals suited for beef cattle production systems, finishing precocity score and growth traits should be considered as selection criteria. |
