Plasma and follicular fluid fatty acid profiles in dairy cows

Composition of follicular fluid to which the preovulatory follicle is exposed may be one of the major factors determining subsequent fertility, as fatty acids are a precursor of hormones involved in dominance, ovulation and atresia mechanisms. The objective of this paper is to observe fatty acid profiles in various lipid classes according to estrogenic activity of follicles. For each of the 18 cows, we analysed plasma and follicular fluid fatty acid profiles of phospholipids, non-esterified fatty acid (NEFA), cholesteryl esters and triglycerides fractions. Follicles were classified as active (ratio oestrogen to progesterone E2/P4 > 1) and inactive (E2/P4 < 1). For seven cows, we get both types of follicles, six had only one active follicle and five cows had only one inactive follicle. The NEFA profile for palmitic acid, stearic acid, oleic acid, linoleic acid, C20:3n6, arachidonic acid and docosapentaenoic acid (DPA; p < 0.001) is different between inactive and active follicles and plasma. Compared with active follicular fluid and plasma, follicular fluid of inactive follicles showed lower stearic acid, higher oleic acid, arachidonic acid and DPA (p < 0.05) in phospholipids. No significant differences were observed in the cholesteryl ester fraction, which is composted mainly of linoleic acid. Triglyceride concentrations were too low to get reliable results. This study suggests that follicles have a specific fatty acid metabolism depending on oestrogen activity.