عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Economic data and performance records from 10 Iranian Holstein dairy cattle herds, as well as milk production and fertility records from Iranian Center of Animal Breeding and Animal Production Improvment were used to estimate the effect of calving difficulty on milk production, fertility and as well on the economic aspects of maternal and direct calving difficulty. Calving difficulty could be divided into 3 classes. Class 1: normal calving; Class 2: calving that needed help by one man worker, and Class 3: calving with serious damage to calf and mother. Milk production decreased about 46 kg and 323 kg in classes 2, and 3 of the calving difficulty incidences, respectively. Calving difficulty caused decreases in fertility performance by 0.22 more inseminations to be performed in class 2 and 0.35 more ones in class 3. Stillbirth was not affected as by class 2 but was intensified in class 3 by 5 percent. Total economic loss attributed to classes 2 and 3 of calving difficulties were $57.76 and $243.83, respectively. Estimated economic value for maternal and direct effect were $37 per unit change in liability per cow/year. Following a correction of the economic values by cumulative discounted expressions, the economic values for maternal and direct effects amounted to $22.79 for direct, and $8.54 for maternal difficulties.