Earlier weaning of calves from Nellore cows and its effects on the fetal programming and on the produtive and reprodutive performance of the next progeny

Abstract

The overall objective presented in this proposal will be to evaluate the effects of anticipating the weaning (150 days vs. 240 days) of calves derived from beef cows on reproductive performance, and weaned calves and next progeny calves performance. A total of 200 pregnant cow-calf pairs (100 primiparous cows and 100 pluriparous) will be selected from the herd and allotted into two groups: (1) anticipated weaning, in which steers and heifers will be weaned at 150 days of age, and (2) conventional weaning, in which steers and heifers will be weaned at 240 days of age. In the Exp. 1, steers weaned in the conventional way or anticipated will be evaluated during rearing phase and termination, and heifers will be evaluated according its reproductive capacity. In Exp. 2 and 3, the next progeny calves will be followed from birth until slaughter (Exp.2, males) or beginning of breeding season (Exp. 3, females). In Experiment 4, several reproductive characteristics will be evaluated in the dams during the next breeding season to detect the effects of weaning in the reproductive performance of cows. Therefore, this management will be evaluated in the previous progeny and in the next as well as in their mothers. In addition, it is intended to evaluate the effect of these two maternal conditions in primiparous and pluriparous cows. (AU)