LH, Prolactin, Estradiol and Progesterone in Bovine Blood Serum during Early Pregnancy

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Abstract
BLOOD serum LH and prolactin were quantified after fertile and nonfertile inseminations in 28 Holstein heifers and progesterone and estradiol were quantified during the first 75 days of pregnancy in eight heifers. Serum LH was highest on the day of estrus and did not vary significantly thereafter during the first 75 days of pregnancy. Pregnant heifers had slightly lower serum LH than non-pregnant heifers (1.0±.1 vs. 1.2±.1 ng/ml, respectively, P<.10) during days 2 through 11 after insemination. Serum prolactin varied significantly (P<.01) among heifers, but prolactin did not change significantly during the estrous cycle or during pregnancy. Serum estradiol decreased from 12.6±2.4 pg/ml at estrus to 8.4±.6 pg/ml by day 4 of pregnancy and ranged from 6.2±.5 to 8.6±1.3 pg/ml during days 7 to 75 of pregnancy except on day 40 (avg 11.1±2.3 pg/ml) when four of eight heifers had elevated estradiol. Serum progesterone increased from 0.4±.1 ng/ml at estrus to 6.8±.4 ng/ml on day 11. Maximum progesterone during the first 75 days of pregnancy was attained by day 18, then progesterone decreased about 20% (P< .05) during the next 4 days and returned to 11.3±1.6 ng/ml by day 35. Copyright © 1973. American Society of Animal Science . Copyright 1973 by American Society of Animal Science.

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