Abstract
In each of six Holstein cows, 5 mg PGF2α (tham salt) was deposited in the uterine horn ipsilateral to the corpus luteum on day 11 of the estrous cycle. With intervening control estrous cycles between each PGF2α treatment, the same cows were given 5 mg PGF2α into the ipsilateral uterine horn on day 15 and on day 7 of the estrous cycle, and five of the six cows were given 5 mg PGF2α into the contralateral uterine horn on day 11. The response of each endocrine or reproductive criterion was similar regardless of day of the cycle PGF2α was administered or whether PGF2α was deposited into the ipsilateral or contralateral uterine horn. After intrauterine PGF2α treatment, 1) luteal diameter decreased (P<.01) from 2.5±.1 to 1.6±.1 cm within 24 hr., 2) serum progesterone fell (P<.01) from 3.6±.3 ng/ml to 1.7±.2, 1.2±.2 and 1.0±.1 ng/ml at 12, 24 and 48 hr., 3) serum estradiol increased (P<.01) from 5.0±1.0 pg/ml to 6.1±.4, 11.3±.7 and 12.7±1.3 pg/ml at 12, 24 and 48 hr., 4) a surge of LH occurred (P2α, treatment did not differ significantly from control cycles in the same cows. In overview, exogenous PGF2α caused dramatic luteolysis in cows, followed by increased estrogen secretion, an ovulatory surge of LH coincidental with onset of estrus, and ovulation. No residual influence of PGF2α was detected on estrous cycles subsequent to PGF2α treatment. Copyright © 1974. American Society of Animal Science . Copyright 1974 by American Society of Animal Science.