Abstract
The influence of protein, methionine, a crystalline amino acid mixture, oil or cellulose in the diet and the method used for diet sterilization on the fresh weight or total nitrogen (N) content of the cecum was examined in germ-free (GF) and conventional (CV) mice. These results showed that the fresh weight of the cecum in GF mice was much higher than that of CV mice fed the same diet, whereas the total N content of the cecum was less in GF mice than in CV mice. The cecum of mice given an amino acid mixture as the N source was lighter than that of mice given a purified whole-egg protein diet as the N source. The effect of the diets on shrinkage of the enlarged cecum in GF mice was insignificant compared with the action of several microbes in the gastrointestinal tract of CV mice.
