Stillbirth and abortion are important functional traits in dairy cattle breeding, from both economic and animal welfare points of view. Stillbirth is realized as doom of a calf that occurs merely prior to, during, or within 24 to 48 h of parturition (Philipsson et al., 1979). Factors influencing stillbirths are diversified. Furthermore, genetic, environmental, and management factors have varying degrees of effectuation on stillbirths. Often it is difficult to determine what causes a calf to be stillborn, however one or more factors (e.g., parity, sex of calf, gestation length) may contribute to a complex collection of events when the final outcome is a stillborn calf. Dystocia has been involved as the main cause of stillbirths; however, about 50% of stillborn calves were from unassisted births (Philipsson, 1997).Stillbirth has …show more content…
Most often attentiveness is drawn to the reality that multiple pregnancies have negative impacts on increased aptitude for abortion, dystocia and post-partum turmoils including metritis, retained placenta, displaced abomasum, ketosis and fatty liver, as well as extension of the calving interval and enlarged culling of cows that gave birth to twins (López-Gatius and Hunter 2005; Max 2011).To the best of our knowledge, this is a one of recently trials to investigate the effects of stillbirth and abortion on subsequent reproductive and production performance of crosses originated from two temperate breeds and managed under subtropical Egyptian conditions. Therefore, the objectives of this study were to estimate the incidence of stillbirth, abortion and twining, as well as, evaluate the effects of stillbirth and abortion on the subsequent reproductive and production performance of the pure HO, BS and their rotational F1 crosses under Egyptian