الكاتب: Multiple References

The effects of various durations of placental retention (6, 8, 12,23,47 and 71 hours) on reproductive performance, milk production, postpartum disease and culling rate were measured to determine a definition of retained placenta. Data from 1010 calvings on 21 commercial Dutch dairy herds were analyzed by parity groups. The reproductive performance of first calf heifers and of second and third parity cows was not significantly affected by the duration of placental retention. However, fourth parity and higher cows showed the best reproductive performance when they expelled their placenta within 6 hours. Retention of the placenta for longer than 6 hours resulted in an increase of 17 days to the first service and 26 additional days open. Older cows showed decreased milk production with an increase in the duration of retention. For first calf heifers there was no cut-off point at which delayed expulsion of the placenta became detrimental to overall performance. Second and third parity cows as well as fourth parity and higher cows demonstrated the highest overall performance in all the parameters tested when they expelled their placentas within 6 hours after parturition.