Weaning weight and optimization of reproductive efficiency in Nellore females subjected to timed artificial insemination

ABSTRACT The objective of this study was to evaluate the effect of timed artificial insemination (TAI) on pregnancy rates, reproductive efficiency, and mean weaning weight of calves at the end of breeding season in Nellore females. In this work, 744 Nellore females were divided into two groups: in group I (n = 396), the females were subjected to natural service during the breeding season, which lasts for 180 days. In group II (n = 348), a hormonal protocol was performed for synchronization of ovulation, and the females were subjected to TAI. Afterwards, these latter females were then serviced by a cleanup bull until the end of the breeding season. The group II obtained a higher pregnancy rate as well as higher reproductive efficiency compared with group I. The weaning weight of group II calves was greater than that of group I. The use of TAI combined with cleanup bulls enables higher pregnancy rates and a better reproductive efficiency in relation to the use of only natural service. In addition, weaning calves born from TAI are heavier than calves born from natural service.