Effect of uterine environment on embryo production and fertility in cows

ABSTRACT

Oocyte fertilization rates in bovines following artificial insemination or natural mating are generally good (~90%). Curiously, only about one third of these pregnancies remain until 30 days post-AI in dairy cows. Thus, most pregnancies are lost between fertilization and early embryonic growth. Although classical pathways describing that lower progesterone post-AI is the main culprit to these early embryonic losses, a number of environmental factors such as heat-stress as well as novel concepts in bovine physiology including the effects of excessive negative energy balanced (NEB) and the insulin-resistant state experienced by high producing cows during the postpartum period can help explain the poor reproductive performance, generally observed in dairy herds world-wide. Thus, expanding the scientific knowledge in these critical areas in bovine fertility related to the evident impact of NEB and/or altered circulating and uterine metabolites in the postpartum period on oocyte quality; gamete transport, uterine environment, and early embryonic growth are of major importance to improve reproductive efficiency in modern high producing dairy cows.