Embryo and foetal loss in beef heifers between day 14 of gestation and full term

Following insemination, reproductive failure in cattle is largely manifeste d as embryo mortality and is a major source of financial loss to livestock producers. Ongoing studies at this laboratory into factors affecting embryo mortality have facilitated the collection of new data on the extent and ti ming of embryo and foetal mortality in cattle. Oestrus was synchronised in 158 beef cross heifers and following artificial insemination, embryo and fo etal survival rates were determined on days 14 and 30 after insemination an d subsequently at calving. Embryo survival rates measured on days 14, 30 an d at full term were similar at 68%, 76% and 71.8%, respectively (P > 0.05). Based on morphological examination, all the 14-day-old embryos recovered w ere assessed as grade 1. These results provide new information indicating t hat most embryo losses in heifers have occurred before day 14 after insemin ation. (C) 2000 Elsevier Science B.V. All rights reserved.