An enzyme histochemical investigation of the intestinal mucosa in diarrheic calves.

Selected enzymes were examined in the small intestine of twelve 2–5 week-old calves, 8 with diarrhea and 4 convalescents. The diarrheic calves showed a reduction of enzyme reactions mainly in the duodenum and middle small intestine, and the crypt reactions appeared most severely affected. In the duodenum, villous alkaline phosphatase, adenosine triphosphate-(ATP)-splitting enzyme, and β-D-galactosidase were reduced in 3 calves; the reaction in the corresponding crypts was decreased in 6 calves for the ATP-splitting enzyme and in 4 calves for the β-D-galactosidase. Six calves showed decrease of villous brush border acid phosphatase, and 3 of villous non-specific esterase. In the middle jejunum, villous ATP-splitting enzyme was reduced in 3 calves, while 5 showed decrease of the corresponding crypt reaction. Convalescents had no enzyme reduction in the duodenum, whereas 1 showed marked reduction of the ATP-splitting enzyme and aminopeptidase in the middle and posterior jejunum. The decreased enzyme reactions in the present material may be caused by immaturity of epithelial cells associated with regenerative crypt hyperplasia and/or microbial destruction of enzymes.