Effect of Dietary Chitosan Oligosaccharide on the Growth,Immune Response and Resistance Against Vibrio splendidus Infection of Sea Cucumber

The present study was conducted to determine the effect of dietary chitosan oligosaccharide(COS)on the growth,immune response and resistance against Vibrio splendidus infection of sea cucumber.The basal diet was supplemented with 0%,0.25%,0.50%,1.00%and 2.00% COS to formulate five experimental diets.The results of 56days feeding showed that the basal diet supplemented with COS increased the specific growth rate of sea cucumber,but no significant difference was observed between the treatments and the control(P0.05).The activity of coelomocyte phagocytosis of sea cucumber was not significantly influenced by dietary COS(P0.05).However,respiratory burst activity of sea cucumbers fed the diets with COS was significantly(P0.05)higher than that of sea cucumbers fed the basal diet.The activity of nitric oxide synthase of coelomocytes was significantly higher in animals fed the diet with 0.50%chitosan COS(P0.05);while the activity of acid phosphatase was decreased.It was significantly lower in sea cucumbers fed the diet with 0.50% COS compared to the control group(P0.05).The sea cucumber challenged with V.splendidus showed that dietary COS conferred better protection to sea cucumber,but no significant difference was observed compared to control group(P0.05).These results suggested that dietary COS has a potential of enhancing the growth and disease resistance of sea cucumber.