Estimação de parâmetros genéticos para características de crescimento e escore de conformação frigorífica em bovinos da raça Santa Gertrudis no Brasil

Abstract

The Santa Gertrudis breed is a synthetic cattle breed that combines adaptability, early growth and finishing ability, and can contribute to improving carcass quality in beef herds. This study aimed to estimate (co)variance components and genetic parameters for growth and carcass conformation traits. A total of 57,729 records (36,569 females and 21,160 males), descendants of 2,749 sires and 16,050 dams, were used, including measurements of birth weight (BW), weaning weight (WW), yearling weight (YW), carcass conformation score at weaning (CCW) and at yearling (CCY). Analyses were conducted using a bi-trait animal model via restricted maximum likelihood (REML), implemented in BLUPF90, with inclusion of the maternal effect for traits evaluated up to weaning. Estimated direct heritabilities (h²) were: BW = 0.42 ± 0.05; WW = 0.17 ± 0.06; YW = 0.25 ± 0.05; CCW = 0.12 ± 0.10; and CCY = 0.08 ± 0.05. For the maternal effect (h²m), estimates were: BW = 0.10 ± 0.02; WW = 0.13 ± 0.05; and CCW = 0.01 ± 0.08. Genetic correlations were positive and ranged from moderate to high magnitude, with the highest values observed between WW–YW (0.97 ± 0.08) and CCW–CCY (0.97 ± 0.93). The strongest association involving BW was with WW (0.45 ± 0.19), and WW showed positive correlations with CCW (0.71 ± 0.85) and CCY (0.69 ± 0.56). It is concluded that there is sufficient genetic variability to promote genetic progress through selection for growth and carcass conformation traits, as well as to produce desirable correlated responses. The novel estimates for CCW and CCY expand the breed’s knowledge base and support decision-making in breeding programs under tropical conditions.