Influência de diferentes seqüências de pastagens no peso e no desempenho reprodutivo de vacas de corte, de dois grupos genéticos, com primeira cria ao pé

Abstract

The objective of this study was to verify the weight gain and reproductive performance of beef cows nursing their first calves. Thirty-nine Angus and 38 Charolais cows were submitted to one of the following treatments: T1 -Natural pasture; T2 - Cultivated pasture during September and October; T3 - Cultivated pasture for two hours per day, during July and August; T4 - Cultivated pasture for two hours per day, during July and August + cultivated pasture during September and October. From November on the cows of all treatments were maintained on natural pasture. Treatment affected (P < 0,01) cow weight after calving, the respective averages were 342, 374, 346 and 387 Kg for T1, T2, T3 and T4 cows. In spite of weight differences after calving, no difference (P > 0,05) were observed in pregnancy rate, wich were, respectively, 6.7, 5.3, 0.0 and 11.1% for T1, T2, T3 and T4. This happened, probably, because of the weight loss that occurred from calving to the end of the breeding season, which was, respectively, -0,073, -0,199, -0,193 and -0,313 Kg daily (P < 0,01). The average pasture availability in Dry matter (DM) / hectare during the breeding season was 716 Kg. The rates of Crude protein and digestibility in DM were 5,53% and 37.69%, respectively, being insufficients to supply all the animals necessity.