The effect of heat on the intestinal and pancreatic levels of amylase and maltase of laying hens and broilers.

The effects of exposing laying hens and broilers daily to intermittent periods of 4 hr heating at 42 degrees C on the intestinal and pancreatic levels of amylase and maltase were investigated. The initial exposure to heat, characterized by heat stress, brought about a significant increase in the duodenum and jejunum parts of the tetra breed hen and only in the duodenum of broilers. The levels of amylase in the distal parts of the intestine of both breeds sharply decreased. The increase in amylase levels in the proximal parts of the intestine under the conditions of initial heating vanished after 3 days of heating; its levels continued to fall in the distal parts. In heat acclimatized laying hens the levels of amylase were lower than those of the control hens both in the intestine and pancreas. The pancreatic level of amylase was reversely related to the levels in the intestine. It is assumed that the intestinal level of amylase is regulated by the pancreas. These findings indicate that the pancreas plays an important role during the adaptation of chickens to heat, through the regulation of intestinal level of amylase. The response in maltase level to heat stress and heat acclimatization was insignificant.