British Cattle Veterinary Association

Conception rates of dairy cows are currently declining at an estimated 1% every year. Approximately 35% of embryos fail to prevent luteolysis during the first three weeks of gestation. Interactions between the corpus luteum (CL), endometrium and embryo are critical to the successful establishment of pregnancy and inadequacies will result in the mortality of the embryo. For example, as little as a one day delay in the postovulatory rise of progesterone has serious consequences for embryo development and survival. Recently, we found that LH support, degree of vascularisation and luteal cell steroidogenic capacity were not the major factors responsible for this luteal inadequacy but are nevertheless essential for luteal development and function.