EFFECT OF DIETARY VITAMIN C SUPPLEMENTATION ON GROWTH AND ANTI-DISEASE ABILITY OF SHRIMP, PENAEUS VANNAMEI

Agrowth trial was conducted to determine the effects of ascorbic acid-2-phosphate with dietary different supplementation levels(0,75,150,300 and 600mg/kg diet)on growth and anti-disease ability of shrimp( Penaeus vannamei )for 10 weeks.Five isonitrogenous and isoenergic diets were formulated as experimental diets.The results showed that in 4-weeks feeding trial,the diet with ascorbic acid-2-phosphate supplementation could significantly increase the growth rate of juvenile shrimp.While the survival rate was not affected( P>0.05).Up to 10-weeks feeding trial,there was no significant effect of increasing dietary ascorbic acid-2-phosphate on growth of shrimp.However the survival rate was improved significantly( P<0.05).The feed convention ratio and protein efficiency ratio were not affected by the dietary vitamin C supplementation levels.The whole body moisture,lipid,protein content and hepatopancreatic ascorbate concentrations were significantly affected by the dietary ascorbic acid-2-phosphate supplementation levels,while there was no significant effect of vitamin C on ash content in whole body.The ascorbic acid concentrations in the shrimp hepatopancreas increased significantly with the increase of the dietary vitamin C supplementation levels,the hepatopancreas ascorbic acid concentrations in the shrimp with vitamin C un-supplementation was the lowest.The superoxide dismutase(SOD)of shrimp serum was not affected by the dietary ascorbic acid-2-phosphate supplementation levels. The phenoloxidase activity, red blood count and lysozyme activity decreased significantly when the dietary without ascorbic acid-2-phosphate supplementation or excess of 150mg/kg supplementation.Based on weight gain rate,survival rate and phenoloxidase activity,the optimal dietary supplementation levels of ascorbic acid-2-phosphate for this diet formulation was 150mg/kg diet.