The Survey of the effects of maternal, fetal and environmental factors at the calving time of dairy cows

The aim of this study was to find out the correlation between the calving time related to the some maternal, fetal and environmental factors such as: age of dam, number of parity, pregnancy duration, calf sex and live weight, rate of still birth, retention of fetal membrane (RFM) and finally the effect of birth of season in Holstein dairy cows. During a 4 years study, the time of 2135 single calving were evaluated. The maternity section was stress free in the herd. The time of parturition stratified into 2 groups, 1-day time from 6 AM to 6 PM and 2-night time from 6 PM to 6 AM. The above factors mentioned were evaluated. Results were analyzed using Chi-square statistical method.It was showed that 54% and 46% cows calved during the day and night time, respectively. One hour period from 08.00-09.00 had the highest deliveries with 119 birth, and at 23.00 had the minimum parturition with 62 births. The rate of RFM during the night and day time was 55% and 45%, respectively (P<0.05). Most (70%) of the still births were occurred during the night (P<0.05). Autumn with 688 calving (32%) and spring with 392 births (18%) had the highest and lowest rate, respectively.With preparing silent and stress free environment in calving time, the negative aspects of birth can be reduced and most of the calving will be occurred during the day time.