Protein restriction in early pregnancy alters fetal and placental growth and allantoic fluid proteins in swine

This study was designed to determine the impact of protein malnutrition during early pregnancy on fetal and placental growth and on the protein synthesis capacity of placental and endometrial tissues. Twelve crossbred sows received 1.8 kg/d of a control (13% protein) or protein-restricted (0.5% protein) diet from the day of breeding to Day 63 of pregnancy, when dissections were performed on each conceptus unit. The de novo protein synthetic rate of placental and endometrial explants was measured using (35)S-methionine. These proteins and the proteins from amniotic and allantoic fluids were separated by polyacrylamide gel electrophoresis. Placental weight was significantly reduced in the sows fed the restricted diet, with a tendency for decreased fetal weight as well. No differences were found due to dietary treatment in de novo protein synthesis or in the electrophoretic patterns of secreted proteins of the placenta or endometrium. The apparent quantity of 3 proteins in the allantoic fluid of the restricted diet fetuses decreased, while 1 protein increased in comparison with that of the control fetuses. These data suggest that protein malnutrition in early pregnancy decreases placental growth, thereby decreasing both fetal growth and the opportunity for compensatory growth upon nutritional rehabilitation.