Follicle Stimulating Hormone Pattern and Luteal Function in Ewes Receiving Bovine Follicular Fluid during Three Stages of the Estrous Cycle2

Abstract

The objectives of this study were to determine 1) the ability of charcoal-extracted bovine follicular fluid (bFF) to suppress endogenous follicle stimulating hormone (FSH) at various stages of the estrous cycle and 2) the effects of suppression of FSH on luteal function and lengths of the current and subsequent estrous cycles. Twenty-six mature ewes were assigned randomly to receive 5 ml of either bFF or saline, subcutaneously, at 8-h intervals on d 1 through 5 (bFF n = 6; saline n = 3), d 6 through 10 (bFF n = 6; saline n = 3) or d 11 through 15 (bFF n = 6; saline n = 2) of the estrous cycle (d 0 = estrus). Blood was collected daily beginning at estrus and continued until the third estrus (two estrous cycles) or 40 d; more frequent samples were collected 2 h prior to initiation of treatment (0600), hourly for the first 8 h of treatment, then every 4 h until 0800 on the first day after treatment, and finally at 1600 and 2400 on that day. Plasma concentrations of FSH were lower (P less than .001) in bFF-treated than in saline-treated ewes. Treatment with bFF reduced (P less than .05) plasma concentrations of progesterone during the current but not during the subsequent estrous cycle. Treatment with bFF did not affect plasma concentrations of estradiol-17 beta. Administration of bFF on d 11 through 15 of the estrous cycle lengthened the interval from the decline in progesterone to estrus and the inter-estrous interval by approximately 3 and 4 d, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)