The effect of raw soya beans upon the digestion of proteins and upon the function of the pancreas of intact chickens and of chickens with ileostomies

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Abstract
Raw and heated soya beans were given to intact chickens and to chickens with ileostomies. The pancreas responsed to raw soya beans by an immediate increase in secretion of pancreatic juice; and by hypertrophy accompanied by an increase in the concentration of the proteases in the pancreas. This adaptive response continued for 6 weeks or longer. The proteases were at their highest in the pancreases of fasting chickens. After eating the heated soya-bean diets there was almost always a decrease In the proteases; the decreases were much greater with raw soya beans. There was little change in the percentage of N in the pancreas after eating, whether before or after adaptation to the raw soya-bean diets. The responses in the pancreas were reflected in the intestinal contents thus: after the initial ingestion of raw soya beans there was a decrease in the proteases of the contents of the small intestine and colon of intact chickens but not in those of the cecums; the proteases in the contents of the small intestines of chickens that had eaten the raw soya-bean diets for 6 weeks were as high as for chickens on the heated soya-bean diet. The proteases of the cecal contents were higher in chickens given the raw soya-bean diet than in those given the heated soya-bean diet; 3 weeks was insufficient time for these adaptive responses. An "unavailable protein fraction" was found in the intestinal contents as indicated by: A greater percentage of N in the contents of the lower half of the small intestine of chickens given ray soya-bean diets as compared with thos3 given the heated soya-bean diets. This increase was not seen in the upper half of the small intestine. K was probably masked by the massive dilution of the dietary N by endogenous N. There was a decrease in the absorption of N from the small intestine of the chickens given raw soya-bean diets. A larger amount of protein N was found in the contents of the small intestine of the chickens given raw soya-bean diets than in those given the heated soya-bean diets.