Effects of non-esterified fatty acids on bovine granulosa cells and developmental potential of oocytes in vitro

Abstract

High yielding dairy cows experience a negative energy balance (NEB) shortly after parturition, which is accompanied by high concentrations of non-esterified fatty acids (NEFA) in blood up to approximately 3 weeks post partum. We hypothesized that the elevated plasma NEFA concentration causes lower fertility by exerting negative effects on granulosa cells and oocytes in the ovary, leading to less viable embryos and insufficient corpora lutea. In two series of experiments, we studied the effects of a realistic NEFA (C18:1) concentration on both the proliferation and the progesterone production of follicular granulosa cells in vitro (part I) and on maturation, fertilization and developmental potential of oocytes (part II). For part I, granulosa cells were added to 4 groups of dishes with four different media and cultured for nine consecutive days. After a preculture period of 42 h, the presence of NEFA had a negative effect on the proliferation of granulosa cells. No effect of NEFA on the amount of progesterone production per cell was observed. For part II, a total of 1804 cumulus-oocyte-complexes were collected from slaughterhouse ovaries. Using a subgroup of 690 COC, maturation medium with NEFA caused a delay in maturation. Using another 1114 COC, fertilization, cleavage, and embryonic development after maturation in presence of NEFA were significantly reduced. We concluded that the presence of NEFA in follicular fluid and blood of post partum cows may reduce fertility due to hampered embryonic development and subnormal CL function.