This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Testart, J. Articles by Thibier, M. Search for Related Content PubMed Articles by Testart, J. Articles by Thibier, M.

Oestradiol-17β, progesterone, FSH and LH in prepubertal calves induced to superovulate

Summary. Fluorogestone acetate (vaginal sponge for 4 days) and PMSG (i.m. injection at the time of sponge insertion) treatment was administered to seven 3-month-old calves to induce superovulation. Samples of peripheral plasma were taken every 4 h during treatment (4 days) and then every 2 h for 7 days. FSH, LH, oestradiol and progesterone were measured by radioimmunoassays. In all calves oestradiol concentrations increased 24 h after PMSG injection and reached the highest levels (41–502 pg/ml) during the preovulatory surge of both gonadotrophins. The surge of LH and FSH occurred from 12 to 22 h after cessation of treatment. The maximum levels of LH and FSH were 11–72 ng/ml and 23–40 ng/ml respectively and occurred within 4 h of each other. Between 40 and 68 h after the LH peak the concentrations of progesterone began to increase from basal values, reaching 24·0–101·7 ng/ml when the animals were killed. A quantitative relationship was found between plasma oestradiol concentration and the numbers of ovulating follicles. Progesterone levels seemed to be related to the numbers of corpora lutea and also to the numbers of unovulated follicles. Gonadotrophin output was not quantitatively related to ovarian activity or to steroid secretion.