Effects of intrauterine infusion of oestradiol-17 and prostaglandin E-2 on luteal function in non-pregnant heifers

Publisher Website
Google Scholar
Abstract
Non-pregnant heifers (4/group) received intrauterine infusions of vehicle, estradiol-17.beta. (150 ng), PG[prostaglandin]E2 (250 .mu.g), or estradiol + PGE2 every 6 h from 1200 h on day 13 to 0600 h on the day of subsequent estrus or 0600 h on day 21 (day of estrus = day 0). Ten of 12 heifers receiving vehicle, estradiol or PGE2 returned to estrus by day 21, whereas none of the heifers receiving estradiol + PGE2 returned to estrus by day 21. Jugular venous progesterone concentrations of vehicle- and PGE2-treated heifers declined rapidly after day 15 and were basal (< 1 ng/ml) by day 20. For heifers receiving estradiol infusions, systemic progesterone levels did not decline until after Day 18, but were again basal by day 20. Heifers treated with estradiol + PGE2 maintained elevated systemic progesterone levels until day 21 after estrus. The corpora lutea of the heifers treated with estradiol + PGE2 were heavier (P < 0.01) and contained more (P < 0.05) progesterone than did corpora lutea of the heifers in the other 3 groups on day 21 (3.4 g and 19.52 .mu.g/g and 1.2 g and 1.65 .mu.g/g, respectively). Estradiol-17.beta. and PGE2, both of which are produced by the bovine conceptus and secreted from the gravid uterus, may act synergistically to maintain luteal function during early pregnancy in the cow.