Influência do escore de condição corporal na taxa de prenhez de vacas zebuínas

Abstract

In beef cattle production, reproductive efficiency is one of the main determinants of productivity and is closely related to calving interval and the achievement of one calf per cow per year. In this context, body condition score (BCS) stands out as a practical tool for assessing the nutritional status and reproductive potential of females, influencing the return to postpartum cyclicity, the response to fixed-time artificial insemination (FTAI) protocols, and pregnancy rates. The objective of the present study was to evaluate the influence of BCS during the breeding season on the pregnancy rate of Zebu cows subjected to FTAI. The study was conducted on a farm located in the municipality of Piracema, Minas Gerais, Brazil, using 88 bovine females (heifers, primiparous and multiparous cows), totaling 103 inseminations throughout the breeding season. BCS was assessed at the beginning of the FTAI protocol and at pregnancy diagnosis, using a scale from 1 to 5 with 0.25-point intervals. Reproductive parameters were also evaluated, including dominant follicle diameter, presence and size of the corpus luteum, estrus score, and reproductive indices (service, conception, and pregnancy rates). Data were subjected to correlation analyses, association tests, and logistic regression. The results showed a conception rate of 68% and a final pregnancy rate of 79.55%. The median BCS was 2.75, ranging from 1.75 to 3.5. Initial and final BCS showed no significant correlation (p > 0.05) with pregnancy diagnosis, as did BCS variation. Nevertheless, a tendency toward a higher probability of pregnancy was observed in females with higher BCS, evidenced by odds ratio values greater than 1. It is concluded that, in well-managed Zebu herds with adequate body condition, variations in BCS during the evaluated period may not significantly impact pregnancy rates.