The effect of thermal environment on the digestion of broilers

Summary Two experiments were conducted to determine the effect of thermal environment on the digestion of broilers. In both experiments the birds were exposed to three temperatures: 5, 21, and 32° C, and relative humidity was maintained at 60%. In experiment one, the amount of chyme in the whole digestive tract was decreased by the cold environment (5° C, 60% relative humidity) and increased by hot environment (32° C, 60% relative humidity), compared with control environment (20° C, 60% relative humidity). The expelling of digesta from the crop or small intestine was suppressed by high temperature (32° C) (p < 0.01). In experiment two, the activities of trypsin, chymotrypsin, and amylase were affected significantly by different environmental temperatures (p < 0.01). Compared to normal environment, the activities of the three kinds of enzymes in intestinal juice were decreased by the hot environment: trypsin (p < 0.01), chymotrypsin (p < 0.05), and amylase (p < 0.01), respectively. The activities of the three kinds of digestive enzyme were not influenced by the cold environment.