Abstract
LH, prolactin and growth hormone (GH) were assayed in jugular, uterine arterial and uterine venous blood obtained from 37 Holstein heifers at 90, 180 or 260 days of pregnancy. None of the three hormones changed significantly during pregnancy. At each trimester of gestation, cows carrying male fetuses had higher jugular serum prolactin (P<.05). A similar tendency was observed for growth hormone, but not for LH. Concentrations of LH in the jugular, uterine artery, and uterine vein were equivalent, but the jugular contained 259% more GH (P<.01) and 61% more prolactin than the average of the uterine vessels. While uterine arterial blood contained slightly more of each hormone than uterine venous blood, the differences did not approach significance. Copyright © 1972. American Society of Animal Science . Copyright 1972 by American Society of Animal Science