EFFECTS OF DIETARY-FAT ON FOLLICULAR DEVELOPMENT AND CIRCULATING CONCENTRATIONS OF LIPIDS, INSULIN, PROGESTERONE, ESTRADIOL-17-BETA, 13,14-DIHYDRO-15-KETO-PROSTAGLANDIN F2-ALPHA AND GROWTH-HORMONE IN ESTROUS CYCLIC BRAHMAN COWS

Brahman cows were used to evaluate dietary fat (3.74% [control] and 5. 20% [treated]) effects on blood hormone and lipid concentrations, foll icular populations, and in vitro steroidogenesis. Cows were fed and ov aries were monitored by ultrasound from d 1 of the first estrous cycle (EC) until the first follicle of the second EC reached 8 mm, at which time ovaries were harvested. Follicular fluid (FF) was collected from large- and medium-sized follicles and assayed for progesterone (P4), estradiol-17 beta (E2), testosterone, cholesterol, and triglycerides. The corpus luteum was removed, minced, treated with LH, and incubated for 4 h. Granulosa cells harvested from the largest follicle were trea ted with forskolin, LH, or FSH and incubated for 48 h. Blood was colle cted during the treatment period and plasma assayed for 13,14-dihydro- 15-keto-prostaglandin F-2 alpha (PGFM), growth hormone (GH), insulin, P4 and E-2. Cholesterol and triglycerides were assayed only from blood samples collected every 7 d. Treated cows had greater (P < .01) plasm a E2 during the first EC and greater (P < .01) P4 during the second EC than controls. Treated cows had elevated (P < .01) insulin following d 16 of treatment, but GH and triglycerides were similar (P > .10) in both treatment groups. Treated cows tended (P = .10) to have greater P GFM peak concentrations than controls. Plasma cholesterol was elevated (P < .01) in treated cows on d 7 of the first EC. Treated cows tended to have greater (P < .09) follicular populations during the ovulatory and first wave of the first and second EC. Treatment did not affect ( P > .10) FF concentrations of P4, E2, testosterone, cholesterol, or tr iglyceride from either large- or medium-sized follicles. There were no differences (P > .10) in steroid hormones produced in vitro.