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Dietary unsaturated fatty acids influence preovulatory follicle characteristics in dairy cows

M Zachut, Volcani Center, Bet Dagan, Israel
A Arieli, Hebrew University, Rehovot, Israel
H Lehrer, Volcani Center, Bet Dagan, Israel
N Argov, Rehovot, Israel
U Moallem, Volcani Center, Bet Dagan, 50250, Israel

Correspondence: Uzi Moallem, Email: Uzim{at}volcani.agri.gov.il

Abstract

Dietary unsaturated fatty acids (UFA) have been implicated in several reproductive processes in dairy cows through a variety of mechanisms. This study examined the effects of periparturient supplementation of rumen bypass fats low or high in proportion of UFA (oleic and linoleic) on preovulatory follicles characteristics. Forty-two 256 d pregnant dairy cows were divided into 3 groups and were fed with a control diet (n=14) or supplemented with fats either low (LUFA; n=14) or high (HUFA; n=14) in UFA. At 14–15 d following behavior estrus the cows received a prostaglandin F2 injection and 48 h later > 7mm follicles were aspirated. Progesterone (P4), androstenedione (A4) and estradiol (E2) were determined in the follicular fluid (FF). Thirty-seven out of 75 follicles that were aspirated between 55 to 70 d postpartum were regarded as E2-active follicles (E2/P4 ratio >1) and subjected for further analysis. The diameter of preovulatory follicles was greater in cows fed HUFA than in those fed control or LUFA. The concentrations and content of A4 and E2 in follicles and E2/P4 ratio were higher in the HUFA group than in both other groups. The P450 aromatase mRNA expression in granulosa cells that were collected from the aspirated preovulatory follicles was also higher in the HUFA cows than in other groups. A significant correlation was observed between E2 concentrations in preovulatory follicles and E2 concentrations in plasma at aspiration. In conclusion, dietary UFA increased the size and elevated steroid hormones in preovulatory follicles which may be beneficial to consequent ovarian function.