Acasalamentos dirigidos como ferramenta impulsionadora do progresso genético de rebanhos bovinos de corte

Abstract

This study aimed to evaluate the influence of genetic improvement tools, with an emphasis on directed mating, on the genetic progress of a herd of Nelore cattle, considering productive and reproductive characteristics relevant to the production system. The study was conducted using genetic data from a farm in Capinópolis, Minas Gerais, Brazil, participating in the ANCP and PMGZ genetic improvement programs. Two periods were compared: I (2017–2019), with selection based on EPDs and morphological mating, and II (2020–2024), marked by the intensification of the use of directed mating. The characteristics evaluated were: weaning weight (P210, kg), yearling weight (P450, kg), scrotal circumference at 365 days (PE365, cm), loin eye area (AOL, cm²), carcass finish (ACAB, mm), stayability (STAY, %), probability of early calving (3P, %), and total economic genetic merit (MGTe). Descriptive statistical analysis of the mean TEPs, supplemented by comparative graphs, allowed for the evaluation of the annual genetic evolution of the herd between periods. For example, weaning weight (P210) had an annual genetic gain of 1.30 kg, or 145.28% higher than in scenario I, and loin eye area (LEA) had an annual gain of 0.40 cm² (100% higher) than in the previous period. The results showed more significant genetic advances in scenario II for most of the selected traits, resulting in greater herd uniformity and reduced standard deviations. The exceptions were for carcass finishing traits, stayability, and probability of early calving, which showed lower annual gains in scenario II due to reduced genetic variability after continuous selection cycles, although they maintained higher genetic means. It is concluded that directed mating proved to be an effective tool in the genetic progress of the Nelore breed herd, contributing to the consistent improvement of the traits used as selection criteria.