Study of consequences and factors affecting the incidence of retained placenta in Holstein dairy cattle of Isfahan province of Iran
The objectives of this study were to 1) describe the risk factors، incidence، production and reproduction consequences of retained placenta in dairy cows، and 2) estimate the financial losses associated with retained placenta. Calving records from March 2008 to December 2013 comprising 59،341 calving were included in the data set. The effects of risk factors on retained placenta incidence were quantified using a multivariable logistical regression model and effect of retained placenta on production and reproduction performance were analyzed using a mixed linear model in SAS software. The average incidence of retained placenta per year was 9. 7 % ranged between 7. 9 to 11. 6 %. Results from the logistic regression analysis demonstrated that calving year، parity number and calving season، twining، dystocia، and stillbirth significantly influenced (P < 0. 01) the incidence of retained placenta. Cow with highest odds of retained placenta were those first parity cows that calved in winter and had stillbirth، twining، and dystocia in recent years. Results showed that a case of retained placenta significantly (P < 0. 05) reduced 305-d milk yield by 320 kg/cow per lactation but had no significant effects on 305-d fat and protein percentages. Depressive effects of retained placenta (P < 0. 05) on reproduction efficiency were quantified by an increase in open days and number of inseminations per conception of 11. 55 ± 1. 48 and 0. 17 ± 0. 02 per cow per lactation، respectively. Economic losses due to retained placenta ranged from $US 144 to 279 with a mean of $US 200 per case. Results of the present study could be useful in cost-benefit analysis of retained placenta management control programs.