Influence of animal, herd and management factors on perinatal mortality in dairy cattle--a survey in Thuringia, Germany.

It was the aim of this study to identify cow/calf, herd and management risk factors on perinatal mortality (PM) in dairy herds from the German federal state of Thuringia. Perinatal mortality was defined as cases of stillborn calves or calves having died within 24 h after birth. From a representative sample of 53 herds (breeds: Holstein Friesian and crossbreedings between Holstein Friesian and Blackpied Dairy Cow), dairy herd improvement (DHI) records were obtained providing information about number of calvings, frequency of PM, parity, calving ease, gender, twin calvings and herd milk yield. Management practices (farm organisation, breeding policies, calving management, hygienic measures, feeding, status of infectious diseases) were recorded using a questionnaire filled in whilst interviewing the herd owner. Data of one year from 46 herds with 13 158 calvings were analysed using logistic regression models applying generalised estimation equations (GEE). The overall frequency of PM was 9.3%. The odds ratio for PM was 5.89, 1.73, 1.68 and 1.67 in cases of dystocia, heifer calving, twin and male calves, respectively. None of the management factors examined in this study remained as significant effects for PM in the final logistic regression model. In conclusion, the results of this study suggest that cow/calf related factors reported as risk factors for PM in many studies in the past such as dystocia, number of lactation, gender and twins were also major determinants of PM in commercial dairy herds in Thuringia. Besides applying appropriate breeding policies herd owners should primarily consider ways of further improving calving management with proper calving supervision and correct calving assistance in order to reduce the risk of PM.