Effects Of Dietary Phosphorus On Growth Performence, Meat Quality,Antioxidative Ability And Immune Function Of Young Grass Carp

A total of540young grass carp (Ctenopharyngodon idella)(282.9±3.3g) were fed diets containing graded levels of phosphorus(0.1%,0.25%,0.38%,0.56%,0.78%å'Œ0.95%diet) for8weeks to investigate the effects of phosphorus on growth performence, meat quality, antioxidate ability and immune funtion. After a period of8weeks feeding trial,30fish with similar weight were randomly slected from each treatment group to conduct a challenge trial with CUSO4for96h.Deficiency syndromes such as anorexia, poor growth were observed in young grass carp fed phosphorus-deficient diet (unsupplemented control group) for8weeks. Phosphorus levels great significantly improved PWG, FE, FI, plasma phosphorus and alkaline phosphatase (P<0.01). The weight of hepatopancreas, intestine weight and intestine length were significantly improved by various dietary phosphorus levels(P<0.01). Diet with optimal phosphorus can elevated the protein content, decrease the lipid content and the flesh cooking loss (P<0.01). The MDA, PC content in muscle, head kidney and spleen was opposite with PWG. The dietary phosphorus significantly affected GSH content, and some antioxidant enzyme activities in muscle, head kidney and spleen (P<0.01). Phosphorus significantly elevated head kidney weight, spleen weight (P<0.01). The lysozyme, addiment C3, IgM of intestine, head kidney, the addiment C3, lysozyme of plasma and IgM of spleen were significantly affected (P<0.01).In conclusion, phosphorus promoted PWG, SGR, FI, FE, plasma phosphorus, alkaline phosphotase of young grass carp. The growth and development of hepatopancreas and intestine of young grass carp were significantly increased with the optimal dietary phosphorus. The quality of flesh was improved in the treatment group fed with suitable phosphorus. Dietary phosphorus depressed the lipid peroxidation and protein oxidation, and improved the ability of removing superoxide radicals and hydroxyl radical in muscle, head kidney and spleen. Meanwhile, phosphorus increased activities of some antioxidant enzymes and GSH content in muscle, head kidney and spleen of young grass carp. Dietary phosphorus could improve disease resistance of young grass carp by enhanced lysozyme and complement C3production. The dietary available phosphorus requirement of young grass carp achived perfect gowth perforrnence estimated by the broken-line regression analysis was0.41%.