Plasma levels of progesterone, Provera, oestradiol-17β, and 13,14-dihydro-15-keto-prostaglandin F in cows treated with Provera-impregnated intravaginal sponges

摘要

Summary. Plasma concentrations of progesterone and Provera were measured daily in 3 cows during 21 days of treatment with Provera-impregnated intravaginal sponges. Plasma concentrations of oestradiol-17β and 13,14-dihydro-15-keto-prostaglandin F (PGFM) were measured hourly from 5 h before until 62 h after sponge removal. The profile of progesterone concentrations indicated that luteolysis occurred at the expected time (Days 19 to 23 of the cycle), even though plasma Provera concentrations were 150–250 pg/ml. The occurrence of peaks of PGFM after sponge withdrawal suggests that PGF-2α release is stimulated by falling levels of progestagen.