Efeito do tipo de parto na eficiência reprodutiva de vacas leiteiras.

Abstract

Dairy farming plays an important role in Brazil’s economy. The reproductive efficiency of herds is fundamental to the productive success of farms, therefore, the prevention of disorders that could affect the reproductive performance of cows is necessary. Based on this, the objective of this study was to evaluate the effect of the type of calving on the occurrence of retained placenta (RP), the interval between calving and the first artificial insemination (1st AI), conception rate in the 1st AI and service period (SP) of crossbred dairy cows. Data were collected from January 2015 to January 2024 from a commercial dairy farm in Lagoa Santa, Minas Gerais. The herd consisted of crossbred dairy cows (Holstein X Gir) with an average production of 25.0 kg of milk/cow/day. The animals in the pre-partum period were kept in paddocks, and the calving was monitored and classified. It was considered a case of RP when the cows did not eliminate the fetal membranes within 12 hours after the expulsion of the fetus. Data from the 1st postpartum AI and fertile AI were also collected to subsequently calculate the calving interval to 1st AI, conception rate in the 1st AI and PS. Data were analyzed using MINITAB program. A total of 6,808 calvings were recorded, of which 325 were abortions, 297 required assistances, 127 were twins, 234 resulted in stillbirths, while the remaining 5,825 were considered normal calving. An effect (P<0.01) of the type of calving was detected on the occurrence of RP, cows with twin calving were 30.71% of RP and with normal calving 8.69% RP. There was a trend of effect (P=0.09) of the type of calving on the interval between calving and the 1st AI, cows with assisted delivery had an interval of 72.41 ± 30.74 days and cows with normal calving of 65.10 ± 28.29 days. No effect of the type of calving was detected on the conception rate in the 1st AI. The PS was affected by the type of calving (P<0.01), cows with assisted calving presented PS of 151.00 ± 101.70 days and cows with normal calving of 124.08 ± 87.56 days. It is concluded that the type of calving affected the occurrence of placenta retention and the reproductive performance of crossbred dairy cows. Cows with normal calving have a lower incidence of RP, a shorter interval from calving to the first AI, and a shorter service period.