Effect of dietary supplementation with long-chain n-3 fatty acids during late gestation and early lactation on mare and foal plasma fatty acid composition, milk fatty acid composition, and mare reproductive variables

The effects of dietary marine-derived n-3 fatty acids (FA) on mare milk and mare and foal plasma FA, postpartum ovarian follicular growth and prostaglandin concentrations were evaluated. Sixty days prior to expected foaling dates, mares were assigned to one of three diets: corn oil (CORN, n = 6), docosahexaenoic acid (DHA) diet (D; 12.64 g/d, n = 7), or eicosapentaenoic acid (EPA) and DHA (ED; 8.84 g EPA, 10.43 g DHA/d, n = 7). Milk and plasma were collected for FA analysis. Follicular data were recorded through the first postpartum ovulation. Post-ovulation serial blood samples were evaluated for prostaglandin F-2 alpha metabolite (PGFM). Supplementation with DHA, or DHA plus EPA resulted in lower linoleic acid and greater EPA and DHA in mare plasma (P < 0.05), greater arachidonic acid and DHA, or EPA and DHA in milk (P < 0.05), and greater DHA, or EPA and DHA in foal plasma (P < 0.05). Days to the first postpartum ovulation was greater (P < 0.01) in ED (22.5 +/- 2.1) compared to CORN (12.5 +/- 2.3) and D (13.3 +/- 2.3) groups. Follicular retention (>= 35 mm) prior to ovulation was longer (P < 0.05) for ED (12.7 +/- 1.9 d) compared to CORN (6.3 +/- 2.0 d) or D (6.0 +/- 2.0 d) groups. Treatment did not affect PGFM concentrations. Maternal EPA and DHA supplementation beginning in late gestation altered the FA profile of milk and mare and foal plasma, and may result in delayed ovulation in the early postpartum period.