Influence of Artificial Diet on Weight Gain and Body Composition of the Neonatal Rat

Abstract

Following an extensive analysis of rat's milk, a basal diet based upon non-fat dry cow's milk was developed for the artificial feeding by intubation of neonatal rats from birth to weaning at 23 days. Since this diet did not support optimal growth, it was supplemented with 1, 5, and 10% rat's milk. With the 5% rat's milk supplement, weight gains were improved to the point where they were equivalent to those of control rats raised by lactating mothers. However, carcasses of pups artificially fed this diet contained 35% more fat than the mother-raised controls. Conversely, rats intubated with the basal diet plus zero, 1, and 10% rat's milk supplements gained less weight than the mother-reared controls but had body compositions similar to those of mother-reared rats. These data indicate that weight gain alone is an inadequate index for evaluation of early diets. Lean body mass and body composition, expressed on an absolute basis appears to be more satisfactory. It is suggested that the technique used in this investigation is suitable for study of the effects of early nutrition on later life.