Maintenance of Pregnancy in Protein-deprived Rats by Transitory Protein Supplements during Early Gestation

Abstract

A study was made to determine the relationship between dietary protein and maintenance of pregnancy in protein-deprived rats at 2 stages of gestation, namely, after mating (day zero) and after implantation of the blastocyst (day 5). By means of transitory feeding, it was shown that there was a critical need for protein at both stages, and that protein supplements supported pregnancy at either stage. Particularly striking was the observation that supplements of protein given 2 or 3 days after inception of pregnancy were sufficient to sustain reproduction in rats deprived of dietary protein at the same high level as in protein-fed controls. Litter size was unaffected by protein deficiency, but fetal growth was retarded. Food consumption of rats receiving a protein-free diet throughout gestation was less than that of rats receiving 20% protein, and the reduction in food intake was greater in protein-deprived rats carrying young than in those failing to litter. The results of the present experiments correspond to those reported previously with a restricted stock diet, and suggest that the effects of restriction were attributable to protein deficiency.