Reproductive efficiency of females bovine animals that had early or conventional weaning of the previous offspring

Abstract

The goal of this proposal is to evaluate the effects of early weaning (150 days vs. 240 days)of offspring from pregnant beef cows in fetal programming and in the performance of the next progeny. In total, 640 pairs of pregnant cows and calves (480 pluriparous cows and 160 primiparous cows) will be distributed in two groups, being (1) early weaning, in which calves will be weaned at 150 days of age, and (2) conventional weaning at 240 days of age. In Exp. 1, calves that will be weaned in an early and conventional manner will be recreated to evaluate the effects of age of weaning on age at puberty e reproductive performance. In Exp. 2, the next progeny (females) of these cows will be monitored from birth until the beginning of puberty. In Exp. 3, several reproductive characteristics will be measured to evaluate the effects of early weaning on the reproductive performance of these cows in the next breeding season. It is intended to analyze the effects of the two different maternal conditions during the gestational period on several factors during the breeding and rearing period of heifers that affect reproductive performance (weight gain, body condition, fat deposition, metabolic profile, age at puberty, and uterine development). In addition, it is intended to compare the effects of these two maternal conditions on primiparous and pluriparous cows. Thus, the effects of this management will be evaluated both on the next generation's calves and on the calves that will be submitted to weaning, and on the performance of the cows. (AU)