Effects on the products of conception of protein supplementation of the diets of rats.

Pregnant rats were ad libitum fed diets of varying casein content from conception. The food intake was measured. The control rats the first 17 days of gestation and 25% casein plus 2.5% DL methionine during the remainder; the second experimental group was given the 25% casein plus 2.5% DL methionine throughout pregnancy. Maternal food intakes were little changed by the supplement, but the rats in the second experimental group ate considerably more. The dietary regimens of the experimental groups had no effect on lean body mass, but did significantly increase carcass fat content. A protein supplement given in late pregnancy, at the time of the fetal exponential growth phase, was found to increase the weight, protein content and cellularity of fetal brains and carcasses. It also increased the weight and protein content of placentas, but had no effect on their cellularity.