NUTRITIONAL STUDIES WITH GUINEA PIG .9. EFFECT OF DIETARY PROTEIN LEVEL ON BODY WEIGHT AND ORGAN WEIGHTS IN YOUNG GUINEA PIGS

Abstract

Male guinea pigs were sup-plied at 2 to 5 days of age with purified diets containing either vitamin-free casein or purified soybean protein and were maintained with the diets for 6 weeks. The protein levels ranged from 20 to 70%. Protein level of the diet influenced growth of the young guinea pig most markedly during the first 2 to 4 weeks. The minimal protein level for maximal growth was 35% with both casein and soy protein. The maximal dietary protein level compatible with good growth was 60% for casein and 70% or more for the soy protein. The dietary protein level affected notably the rate of growth of the liver and testes. The relative weights (as a percentage of body weight) of the adrenals, pancreas and heart, were not influenced by the dietary protein level. The level of soy protein had a slight effect on the relative weights of the kidneys and spleen, whereas casein had little, if any, effect. The relative weights of both liver and kidneys were greater in the animals fed soy protein than in those fed casein.