Abstract
Summary
Insulin, free fatty acids (FFA), and glucose were measured in blood sera from 37 primiparous Holstein heifers and their fetuses on Day 90, 180, or 260 of gestation. Blood was collected from the uterine artery and the uterine vein of the heifers, by cardiac puncture in the 90-day fetuses and from an umbilical artery and vein in 180- and 260-day fetuses.
The average serum insulin concentration was higher (P < 0.05) in male than in female fetuses although the average of the two increased (P < 0.05) during gestation. The overall mean of fetal insulin was only 55% of that of the dam (P < 0.05) and the difference was greatest at 90 days gestation.
Fetal FFA decreased (P < 0.05) during gestation, but maternal FFA increased (P < 0.05) as pregnancy progressed. Maternal FFA were higher (P < 0.01) than fetal FFA and the heifers carrying male fetuses had higher (P < 0.05) average FFA concentrations than heifers with male fetuses.
Average fetal glucose decreased (P < 0.05) from Day 180 to 260 of gestation and the overall mean of fetal glucose was lower (P < 0.05) than maternal glucose.
We conclude that, during gestation, fetal insulin increased while FFA and glucose decreased. In contrast, maternal insulin decreased and FFA increased but glucose remained constant.
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