Risk factors for perinatal mortality in dairy cattle: cow and foetal factors, calving process.

It was the aim of this study to identify risk factors of perinatal mortality (PM) on a large dairy farm in Germany. Four hundred and sixty-three cows were observed continuously around calving. Data such as the lactation number, body condition score, pelvic measurements, duration of second stage of labour (SSL), degree of abdominal press (AP), presentation/position/posture of the calf, calving classification, various measurements of the calves and every action of the barn staff were documented. Calves born dead and those that died within 24h were classified as cases of PM. Logistic regression was performed to identify risk factors for the dependent variables PM, SSL and AP. 9.7% of all calves born (n=483) were classified as PM. In the logistic regression model, only SSL and presentation/position/posture of the foetus remained as significant effects for PM. The odds ratio for PM was 0.20, when SSL was < or =120 min, and 0.33, when the calves were born in anterior presentation, upper position and normal posture. With regard to SSL, primipara, insufficient AP, assisted calvings and as a trend, work shift changeover, these were risk factors for a prolonged SSL beyond 120 min. The risk for insufficient AP was lower when the calves were born spontaneously, in anterior presentation and as single calves. In conclusion, the duration of SSL and presentation/position/posture of the calf seemed to be key risk factors for PM. Interventions should be considered when SSL lasts longer than 2h. Insufficient monitoring around parturition had a negative effect on the duration of SSL and thereby, indirectly on PM.