[Comparison of vaginal devices CIDR and PRID in ovariectomized cows using hormone analysis]

Plasma concentrations of progesterone and estradiol were compared in 7 ovariectomised cows after application of 2 different intravaginal releasing devices. Peak concentrations of 4-6 ng/ml progesterone were found within 2 hours after application of the devices. From day 2 to day 6 concentrations sank continuously to 2 ng/ml. Progesterone levels of 1-2 ng/ml prevailed from day 6 to the day of removal of the pessaries (day 12 for PRID, day 15 for CIDR). No differences between the two devices were detected. Increased concentrations of estradiol were found for PRID only, reaching maximum levels of 6-7 pg/ml plasma 150 minutes after application.