Influência do componente genético materno no desempenho de progênies ao desmame da raça Nelore

Abstract

This study aimed to evaluate the influence of classes of Expected Progeny Differences (EPDs) for MP120, MP210, MTP210, DP210, and DPAV on calf weaning weight (CWW), cow weight at weaning (CWT), and weaning ratio (WR) in Nellore cattle. Data from 339 calves born to 192 cows belonging to a herd participating in the National Association of Breeders and Researchers (ANCP) Program were used. The EPDs were classified into three groups based on the mean and standard deviation. Statistical analyses were performed using SAS software through fixed linear models, considering the effects of EPD classes, contemporary groups, and reproductive category. Least-squares means were compared using the Tukey–Kramer test at the 5% significance level. The superior classes of maternal EPDs showed higher means for calf weaning weight and weaning ratio, without a significant increase in cow weight. For DP210, both calf weaning weight and cow weight increased, whereas no significant difference was observed for weaning ratio. In contrast, cows in the superior DPAV class were heavier but did not wean heavier calves, resulting in lower relative efficiency. It was concluded that selection for maternal ability and direct P210 EPD may favor heavier calves at weaning without excessively increasing cow weight, thereby contributing to greater efficiency and profitability of cow–calf production systems.