Effect Of Dietary Carbohydrate On Digestive Enzyme Activities And Related Physiological Indexes In The Southern Catfish (Silurus Meridionalis Chen) Juveniles

The experiment was conducted to the southern catfish Silurus meridionalis in a recirculating culture system at 27.0±0.5℃. Amylase and protease activities of stomach, gut and pancreas were measured in the southern catfish juveniles fed diets containing isonitrogenous (40% protein), isolipidic (10% lipid) and different starch content (0%, 12% uncooked and 12% gelatinized starch) at the 0, 2^nd and 4^th week. Amylase activities were also determined with the uncooked and gelatinized starch substrate, respectively. The related physiological and biochemical indexes were also measured. The aim of the study was to discuss the biochemistry mechanism of dietary carbohydrate utilization in the southern catfish, and provide some base of the characteristic of dietary carbohydrate digestion in the carnivorous fish. The major results were as following:1. The basic level of amylase activities (0.073 U/mg protein for stomach and 0.108U/mg protein for gut) in the southern catfish was higher than those of some other carnivorous fishes. In all the three groups, amylase activities of stomach and gut increased significantly with the prolonged feeding period, while the activities of the pancreas did not.2. No significant difference was found in amylase activities of stomach, gut and pancreas between the uncooked and gelatinized starch group at the 2^nd and 4^th week. Protease activity of pancreas in the gelatinized starch group was significantly higher than that in the uncooked starch group at the 2^nd week(p<0.05).3. In the stomach of uncooked and gelatinized starch group, amylase activity using...