Sodium intake by pregnant cows and plasma aldosterone and cortisol concentrations in the fetus during late pregnancy.

The purpose of this study was to evaluate the influence of maternal dietary Na intake on the plasma concentrations of aldosterone and cortisol in cows and their fetuses during late pregnancy. Seven cows received a diet with normal amounts of Na (25 g Na per cow/d) and seven others an Na-loaded diet (210 g Na per cow/d) during the last 40 d of gestation. Maternal and fetal blood samples were collected regularly during the last month of gestation through jugular vein puncture and cotyledonary artery indwelling catheters. Serum Na and K concentrations and plasma osmolalities increased, but concentrations of aldosterone decreased in maternal and fetal plasma when cows were fed the Na-loaded diet. Diets did not modify concentrations of cortisol in maternal and fetal plasma. Thus, an increase in Na intake by dams influenced concentration of Na and K in fetal plasma and fetal adrenal secretion of aldosterone.