Effect on the Young Rat of Maternal Protein Restriction

Abstract

The effects on the young of restricted maternal protein intake and the duration of these effects were studied. Pregnant rats fed a diet containing 6% casein as the sole source of protein produced litters of pups with decreased total body weight and length, decreased liver and kidney weights and increased heart, brain, and thymus weights in relation to total body weight. There were no macroscopically observable congenital abnormalities or differences in various indexes of maturation. Pairbred protein-restricted and control litters were then matched in number, weight, and sex. Half of each litter was given at birth to the other dam of the pair to suckle. Lactation failure in the dam is the apparent cause of death in pups suckled by protein-restricted dams. Pups from litters in the protein-restricted group suckled by control dams showed an increased mortality rate and a decreased growth rate which persisted to the age of 76 days. It is suggested that these young lack sufficient vigor at birth to obtain adequate nourishment by suckling. There was almost complete mortality of protein-restricted pups suckled by control dams when no control pups were available to stimulate lactation. The postnatal effects of prenatal protein restriction are, therefore, the sum of effects observed in the newborn and their sequelae plus the consequences of inability to suckle adequately postnatally. It was demonstrated that reduction of total maternal food intake does not affect the young since young in pair-fed litters were indistinguishable from controls.