Metabolic Response to Dietary Carbohydrate to Protein Rations in Carp

抄録

Common carp Cyprinus carpio were fed at a constant feeding rate for 30 days on isoenergetic diets containing different levels of carbohydrate (4-58%) and protein (65-27%), and activities of several hepatopancreatic enzymes together with growthperformance were determined. Dietary inclusion of adequate levels of carbohydrateimproved the growth and feed conversion and exerted a protein-spar-ing effect. With increasing dietary carbohydrate levels and decreasing protein levels, the activities of hepatopancreatic glucosephosphate isomerase, glucose-6-phosphate and phosphogluconate de-hydrogenases, and malic enzyme as well as hepatopancreatic glycogen and serum triglyceride contents increased, while those of glucose-6-phosphatase, arginase, GOT, and GPT together with serum free amino acid concentrations decreased. Therefore, high correlation coefficients were obtained between dietary carbohydrate levels and these biochemical parameter concentrations. The results suggest that dietary carbohydrate stimulates glycolysis and lipogenesis and depressesgluconeogenesis and amino acid degradation in the hepatopancreas. This comprehensive regulation of nutrient metabolism may ac-count for the protein-sparing effect exerted by dietary carbohydrate.