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 evaluatethe effects of stillbirth on lactation performance in Holstein dairy cows. Data were obtained from a dairycattle herd located in Isfahan province, Iran. The logit of the probability of stillbirth was modeled usinglogistic regression and the effect of stillbirth on lactation performance was analyzed through mixed linearmodel using 12283 lactation records on 5201 cows. The results showed that 6% of the calves born die within48 h of birth. The results of logistic regression analysis demonstrated that the frequency of stillbirth issignificantly influenced (P 0.05) by calving year, parity number and calving difficulty. The stillbirthfrequency was found to be significantly higher for first parity cows, (P 0.05). Also, calving difficulty wasshown to be significantly associated with increased risk of stillbirth (P 0.05). Mixed linear model analysisresults demonstrated that stillbirth significantly reduced milk and fat yield (P 0.05), but had no significantimpact on milk fat percentage (P≥0.05). The 305 d milk and fat yields for cows with stillbirth were estimatedto 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.