Periparturient Concentrations of Prolactin, Progesterone and the Estrogens in Blood Plasma of Cows Retaining and not Retaining Fetal Membranes2

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Abstract
Blood was sampled daily from 22 Holsteins (15 cows and seven heifers) to compare concentrations of hormones in plasma among animals retaining (RFM) and those not retaining (NR) fetal membranes. Blood was collected 6.8 ± ; .3 days before to 2 days after calving. Six cows and one heifer did not release their fetal membranes within 12 hr post-partum (RFM). Average changes among days in concentrations of prolactin, progesterone, estrone, estradiol-17² and estradiol-17α (residual estradiol) in blood plasma were significant and similar to data reported by others. Compared to animals in Group NR, periparturiently, those in Group RFM had higher (P<.01) average progesterone (3.4 ± ; .3 vs 2.3 ± ; .1 ng/ml), lower (P<.06) average estradiol-17² (225 ± ; 22 vs 288 ± ; 20 pg/ml) and lower (P<.05) average prolactin (34 ± ; 3 vs 42 ± ; 3 ng/ml). There were no group differences for estrone and estradiol-17α. No day X group interactions were significant except for estradiol-17α (P<.01). Concentrations of estradiol-17α increased daily from 6 to 1 days before calving in animals of Group RFM and decreased daily in animals of Group NR. Increased progesterone, decreased estradiol-17β and possibly decreased prolactin in blood plasma of animals in Group RFM as compared to those in Group NR may indicate asynchrony of hormonal mechanism(s) that normally synchronize birth and release of fetal membranes. Copyright © 1977. American Society of Animal Science . Copyright 1977 by American Society of Animal Science.

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