Manejo de ordenha sobre o desempenho produtivo e reprodutivo de vacas F1 Holandês-GIR

Abstract

Assessing the effects of calf presence during milking or infection of oxytocin on milk produc-tive and reproductive performance of F1 Holstein-Gyr crossbred cows. Seventy four cows were randomly assigned to one of two groups. In one group (BP) cows were milked in the presence of the calf and suckled post-milking for 30 minutes. In second group (OT) cows were milked in the absence of the calf and were injected with 2.0 IU of oxytocin (Postipofisin ®, Hertape Calier), immediately before milking. To test the differences between the means of production parameters, transformed somatic cell count (CSS), service period and interval calving-first artificial insemination was used for Turkey at 5% probability. The variables insemination rates, percentage of pregnant cows and BCS were evaluated using nonparametric statistics. Accumulative 30, 60, 90, 120 and 150 days milk yield, initial milk, production at peak, levels of protein, lactose ,total solids, SCC and body condition score did not differ be-tween treatments (p>0.05). The cows treated with oxytocin had a lower decline rate on milk production and higher milk fat content at 90 and 120 days of lactation (p<0.05). OT cows had lower interval from calving to first insemination, shorter period of service, higher rate of in-semination and percentage of pregnant cows up to 90 days postpartum (p<0.05). Given the superior productive and reproductive performance of the animals treated with oxytocin, in-tends to recommend this practice as an alternative management for production systems com-posed of F1crossbred Holstein-Gyr animals, which target at cow milking in absence of calf.