A Meta–Analysis of the Impact of Parity on Dystocia and Stillbirth in Holstein Cattle

Dystocia and stillbirth are major factors reducing the productivity of dairy cattle. The objective of this study was to determine the effect of parity on the rates of dystocia and stillbirth. A meta–analysis was conducted to investigate the impact of first parity (primiparous) and later parities (multiparous) on dystocia and stillbirth in Holstein cattle. A total of 30 and 19 papers were analyzed for evaluation of two traits. Results revealed that primiparous cattle are more susceptible to dystocia [Odds Ratio (OR) = 2.68, 95% Confidence interval (CI) 2.51 to 2.85], stillbirth (OR = 2.18, 95% CI 1.84 to 2.58) as compared with multiparous. These results supported the opinion about the importance of considering primiparous and multiparous as different traits in genetic evaluation and shed light on the importance of improving genetics and environment of heifers to minimize the effect of dystocia and stillbirth in Holstein cattle.