The level and origin of amylase (EC 3.2.1.1) in the digestive tract of chicks receiving trypsin inhibitors in their diet.

1. Amylase (EC 3.2.1.1) activity found in the intestinal tract of chicks posterior to the stomach is of endogenous origin, as amylase in the food is inactivated by the low pH in the stomachs. 2. Ingestion of raw soya-bean diet (RSD) or of heated soya-bean diet (HSD) supplemented with trypsin inhibitors induced higher amylase activites in the lower part of the small intestine and caecum as compared with HSD. 3. Ingestion of RSD after ligation at the end of the duodenum, end of the ileum or one of the cacea, or injection of soya-bean trypsin inhibitor into a aligated caecum, indicated that there is no amylase synthesis by the intestinal tract cells or microflora as a response to the presence of RSD or trypsin inhibitors. 4. It seems that amylase found in the digestive tract of the chick is of pancreatic origin and the RSD or trypsin inhibitors induce higher pancreatic amylase secretion than HSD which (the additiona amylase) accumulates mainly in the caeca.