Relação do escore de condição corporal na eficiência reprodutiva de fêmeas Nelore

Abstract

Brazilian beef cattle farming is in constant evolution and expansion, which makes the adoption of new technologies and innovations essential to optimize the entire production process. In this context, the cow-calf phase is considered the foundation of the system, and ensuring its good performance requires the implementation of management practices that enhance the reproductive efficiency of the animals in order to guarantee consistent and high-quality calf production. Physiological aspects of cows can directly impact reproductive performance, with body condition score (BCS) being a factor that may be associated both with the return to cyclicity and with the results obtained from the use of reproductive biotechnologies, such as fixed-time artificial insemination (FTAI). The present study aimed to evaluate the effect of body condition score on the reproductive efficiency of Nelore females subjected to FTAI. The study used the Nelore herd from the Capim Branco Experimental Farm, Federal University of Uberlândia (UFU). The following data were collected: body condition score at the beginning of the first FTAI protocol and at pregnancy diagnosis at the end of the breeding season, conception rate at the first FTAI, and the percentage of pregnant cows at the end of the breeding season. The data was analyzed by logistic regression, including BCS categories in the model. The results indicated that there was no significant effect of BCS on the conception rate at the first FTAI. However, when analyzing the categories of BCS variation, a relationship with pregnancy rates at the end of the breeding season was observed: cows that gained 0.25 to 0.75 BCS points had a pregnancy rate of 73.53%; those that gained more than 1.0 BCS point had 79.07%; while cows that lost 0.1 to 1.5 BCS points had only 37.50%, and those that maintained their BCS had 53.89%. It is concluded that body condition score influences the reproductive efficiency of the herd, as cows that gained BCS during the breeding season showed higher pregnancy rates than those that lost or only maintained their initial score.