| Abstrakt: |
Blood sera were taken from 37 bovine fetuses at 90, 180 or 260 days of gestation and from 10 neonates to determine serum levels of LH, GH and prolactin by radio-immunoassays. Umbilical artery and vein contained equivalent quantities of each hormone at each stage of gestation. LH was highest in 90-day fetuses (3.0 ng/ml) and decreased (P<.01) to 1.28 ng/ml at 180 days, to 0.85 ng/ml at 260 days of gestation and to 0.45 ng/ml during the week after birth. Female fetuses had higher (166%, P<.01) LH than males at 90 days and at 180 days (20%, N.S.), but not at 260 days gestation or after birth. Fetal serum GH increased (P<.01) from 90 to 180 and to 260 days (42, 65 and 103 ng/ml, respectively), and averaged 27 ng/ml during the week after birth. Sex of the calf did not influence the level of serum GH or prolactin. Fetal serum prolactin increased (P<.01) from 4 ng/ml at 90 days to 43 ng/ml at 180 days and 61 ng/ml at 260 days. Neonatal prolactin decreased (P<.01) from 101 ng/ml at birth to 42 ng/ml 2 days later.LH and GH were higher (P<.01) in fetal blood, but prolactin was higher (P<.01) in maternal blood. Fetal GH and prolactin increased while LH decreased during pregnancy. These differences suggest that the fetus was the principle source of the hormones found in fetal serum. |
