Acute follicular response to FSH in heifers downregulated long term with a GnRH agonist and with suppressed ovarian follicular growth

M J D'OcchioPietro S Baruselli


The objectives of this study were to (1) ascertain ovarian follicular status in heifers where the pituitary gonadotrope cells producing LH and FSH were downregulated by long-term treatment with a GnRH agonist and (2) characterize the acute superstimulation of follicular growth in response to FSH in heifers where the pituitary was downregulated with a GnRH agonist. At the start of the study, heifers (3 year old) were implanted with GnRH agonist (n = 20) or received no treatment (control, n = 5). After 6 months, follicular growth in heifers implanted with GnRH agonist was restricted to early antral follicles (2-4 mm). At this time, these heifers were allocated to four groups and follicular development was superstimulated with FSH as follows: group 1 (n = 5) and group 2 (n = 5), a conventional FSH protocol with injections over 4 days (Days 0-3) with Group 2 receiving two times the normal dose of FSH; group 3 (n = 5), a single injection of FSH in saline on Day 0; group 4 (n = 5), a single injection of FSH in slow-release polyvinylpyrrolidone on Day 0. Follicular growth in the control heifers (n = 5) was superstimulated using the conventional 4-day FSH protocol. On Day 5, heifers in groups 1 and 2 had similar (P > 0.05) numbers of f...Continue Reading


Jan 1, 1992·Journal of Reproduction and Fertility·G P AdamsO J Ginther

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