A precocidade sexual pode influenciar na eficiência produtiva de fêmeas da raça Nelore?

Abstract

The objective of this study was to evaluate if sexual precocity influences on the productive efficiency of Nelore females. The data used in this study was obtained from a registered purebred (PO) Nelore breeding herd located in Capinópolis (MG). A total of 326 calves and their respective dams were evaluated for the following traits: calf weaning weight (CWW), cow body weight at weaning (CBW), and weaning ratio (WR), recorded in the years 2023, 2024, and 2025. Reproductive females were classified according to the following reproductive categories: early primiparous (EP); early reconception (ER); non-early primiparous (NEP); non-early multiparous (NEM); and early multiparous (EM). For the parametric analysis of variance, the animals were divided into contemporary groups, considered as blocks, according to the environmental sources of variation: sex, year of birth, and the calf’s season of birth, the means were compared using Tukey’s test, performed in RStudio®. Block effects were significant (P < 0.001) for all evaluated traits. Calves from early primiparous females showed lower weaning weight (195.75 kg) compared with the other categories. Calves from early reconception females (219.86 kg) were similar to those from non-early primiparous females (230.66 kg) (P<0.05) and lower than those from non-early multiparous (242.06 kg) and early multiparous females (238.3 kg), which did not differ from each other. Calves from non-early primiparous females showed intermediate values. Regarding cow weight at calf weaning, early primiparous females (427.27 kg) were also lower than all other categories. Early reconception females (464.31 kg) and non-early primiparous females (484.63 kg) were similar, whereas non early multiparous (514.51 kg) and early multiparous females (506.11 kg) were higher and similar to each other, with non-early primiparous females again showing an intermediate pattern. No significant differences were observed for weaning ratio (P<0.05) among the categories. Considering the equation (WR = CWW / CBW), both numerator and denominator decreased proportionally, resulting in a stable quotient. Therefore, the lower calf weight was compensated by the lower cow weight. These results indicate that selection for sexual precocity did not affect the productive efficiency of Nelore females.