Tipo de parto influencia a eficiência reprodutiva de vacas leiteiras que não apresentam retenção de placenta?

Abstract

Brazil is a milking reference country, thus reproductive efficiency is one of the most importante aspects to be evaluated, since reproductive performance directly affects the profitability of farming, since it will affect milk production per day of the cow’s lifetime, replacement animal numbers, production costs, genetic evolution, and other aspects. Calving is a critical moment for the cow, and problems at calving can reduce the reproductive and productive performance. Problems at calving increase the chances of retained placenta (RP), but no data has been found on the effects of the type of calving on reproductive performance when the cow does not have RP. The aim of this study was to evaluate the reproductive efficiency of cows from a comercial dairy farm in Minas Gerais – Brazil which did not have RP. Data was collected on calving day, calving conditions (normal, assisted, abortion, stillborn or twins) and insemination performed. From this data the interval between calving and the first AI were calculated. Statistical analyses were conducted using logistic regression and variance analysis in MINITAB program. Statistical difference was consideres when P ≤ 0.05 and trend when 0.05 < P < 0.10. A total of 2,422 calvings were recorded, 2135 of which were normal, 111 were abortions, 69 were assisted, 67 were stillbirths and 40 were twins. In cows that were assisted at calving, the service period was 144.00 ± 102.60 days.. There was no effect of calving type on the interval between calving and the first AI, and also no effect of calving type on the conception rate at the first AI. It can be concluded that the type of calving affects the reproductive efficiency of dairy cows, regardless of the occurrences of retained placenta, since cows that required some kind of assistance at calving had a longer service period.