Growth Potencies and Effects on Digestive Functions of an Amino Acid and a Casein Diet in Rats of Three Strains

Nutritive values and effects on the digestive functions of chronic feeding of an amino acid (AA) diet were compared with those of feeding a casein diet used three strains of male weanling rats under conditions of maximum growth. We demonstrated that the responsiveness to the casein and amino acid diet were different between rat strains. Growth and food intake in the AA group were clearly less than those in the casein group in Tokushima-Wistar rats, both parameters were the same in SLC-Wistar-St rats, and only growth was less in Sprague-Dawley rats fed the AA diet. The weights of stomach and small intestine, and the ileum activities of sucrase in all strains rats fed an AA diet were higher than those rats fed a casein diet, which indicates that larger and longer chyme remaining in the lumen, and slower absorption of nutrients in the AA groups.