Effects of Polyunsaturated Fatty Acids on Reproductive Processes in Dairy Cattle

Growing evidence indicates that the design and delivery of supplemental unsaturated fatty acids to the lower gut for absorption (specifically linoleic acid, linolenic acid, EPA and DHA) may target reproductive tissues to alter reproductive function and fertility. Improvement in reproductive performance involves stimulation in ovarian activity (follicle development) in the postpartum period, and possibly improved pregnancy rates due to increased production and/or decreased clearance of progesterone. Changes in follicular dynamics can be affected by fat supplementation involving potential alterations in ovarian sensitivity to metabolic hormones such as bST, insulinlike growth factor-I and gonadotrophins (LH and FSH). In bovine endometrial cells, both EPA and DHA can decrease secretion of PGF2α in vitro. In addition, the suppression of uterine prostaglandin secretion by omega-3 fatty acids has been demonstrated both during the estrous cycle and in the immediate postpartum period. Both EPA and DHA appear to be polyunsaturated fatty acids that are nutraceuticals or functional components of feeds that have a specific physiological effect, other than a purely nutritional effect. For example, EPA appears to interact with endometrial cells to stimulate steady state concentrations of PPARδ mRNA, and expression of PPARδ differed in early pregnancy (i.e., day 17) between cows treated with or without bST. In vitro, EPA interacted with the antiluteolysin, Interferon-τ, to cause an additive suppression in PGF2α secretion. Such affects may contribute to the beneficial effects of feeding fatty acids on reproductive performance.