Factors affecting stillbirth and effects of stillbirth on subsequent lactation performance in a Holstein dairy herd in Isfahan

The purposes of this study were to estimate the effects of risk factors on stillbirth parturition and evaluate the effects of stillbirth on lactation performance in Holstein dairy cows. Data were obtained from a dairy cattle herd located in Isfahan province, Iran. The logit of the probability of stillbirth was modeled using logistic regression and the effect of stillbirth on lactation performance was analyzed through mixed linear model using 12283 lactation records on 5201 cows. The results showed that 6% of the calves born die within 48 h of birth. The results of logistic regression analysis demonstrated that the frequency of stillbirth is significantly influenced [P<0.05] by calving year, parity number and calving difficulty. The stillbirth frequency was found to be significantly higher for first parity cows, [P<0.05]. Also, calving difficulty was shown to be significantly associated with increased risk of stillbirth [P<0.05]. Mixed linear model analysis results demonstrated that stillbirth significantly reduced milk and fat yield [P<0.05], but had no significant impact on milk fat percentage [P >/= 0.05]. The 305-d milk and fat yields for cows with stillbirth were estimated to be 8274.17 +/- 100.79 and 245.60 +/- 3.7 kg compared to 8865.60 +/- 88.16 and 259.36 +/- 3.2 kg for cows that had a live calf, respectively

Risk factors for retained placenta and the effect of retained placenta on the occurrence of postpartum diseases and subsequent reproductive performance in dairy cows

The objectives of this study were to determine the risk factors for retained placenta by evaluating several reproductive factors in individual cows, and to determine the effects of retained placenta on the occurrence of postpartum diseases and subsequent reproductive performance in dairy herds. The health status, cow parity, calving, and breeding dates were recorded from 805 calvings in nine dairy herds from October 2000 to March 2004. We used logistic regression to evaluate the effects of these factors on the incidence of retained placenta. A stepwise procedure, used to obtain the appropriate model with alpha = 0.05, revealed that abnormal partus and gestation length were important risk factors for retained placenta. The occurrence of endometritis and metabolic disorders was greater (p<0.01) in the group with retained placentas than in the control group. The mean intervals from calving to first service and conception were prolonged (p<0.05) by 7 and 18 days, respectively, in the group with retained placentas compared to the control group. These results suggest that abnormal partus and gestation length are strongly correlated with the development of retained placenta, which increases the occurrence of postpartum diseases and subsequently decreases reproductive performance in dairy herds.