First postpartum ovulation, metabolites and hormones in follicular fluid and blood in transition dairy cows supplemented with a Saccharomyces cerevisiae fermentation product.

We hypothesized that feeding a Saccharomyces cerevisiae fermentation product (SCFP) from -4 through +7 wk (calving = Day 0) facilitates early first postpartum ovulation and alters blood and follicular fluid concentrations of glucose, beta-hydroxybutyrate (BHB), free fatty acids (FFA), and steroid hormones favorable to subsequent fertility. Holstein cows were fed individually a SCFP product (n = 24) or served as controls (n = 23). Blood samples were collected at wk -4 and -2 from expected calving and at 1, 2, 5, and 7 wk postpartum to determine plasma concentrations of FFA and BHB. Early spontaneous ovulation (progesterone > 1 ng/mL or corpus luteum presence by postpartum median Day 33) or late ovulation was determined. Plasma FFA in weekly samples was not affected by SCFP supplementation, but FFA was greater (P < 0.01; week by ovulation status) in late compared with early ovulating cows during and after postpartum wk 2. Plasma BHB in weekly samples was greater (P = 0.03) in SCFP than control cows and tended (P = 0.06) to be greater in late than early ovulating cows. Cows were exposed to ovulation synchronization (GnRH, PGF, and GnRH on Days 33, 40, and 43 ± 3, respectively). Transvaginal dominant follicle aspiration was conducted at Day 50, 7 d after GnRH on Day 43. Metabolites (FFA, BHB, and glucose) and steroid hormones (progesterone, androstenedione, and estradiol) measured in follicular fluid and blood samples collected at aspiration revealed that androstenedione in serum was numerically less (P = 0.11) in SCFP-treated compared with control cows, whereas androstenedione in serum was less (P < 0.05) in late than early ovulating cows. Concentrations of BHB (r = 0.75) and glucose (r = 0.52) in follicular fluid were positively correlated (P < 0.01) with those in blood. Body weight at calving and Day 42 was less (P ≤ 0.05), and energy balance through Days 28 and 42 was more positive (P < 0.05) in early than late ovulating cows and in SCFP-supplemented compared with control cows (P < 0.05). Dry matter intake, daily milk yield, and yields of fat, protein, lactose, and total solids were less (P < 0.01) in early compared with late ovulating cows, whereas milk fat percentage was increased (P < 0.01) by SCFP supplementation. We conclude that elevated postpartum BHB and FFA in plasma, greater negative energy balance, and greater milk yield and components were associated with later postpartum ovulation, but metabolites and steroid hormones in blood and follicular fluid were unaffected by SCFP treatment or ovulation status except for androstenedione.