Effects of Addition of β-Carotene and Astaxanthin into Diet Containing Equal Vitamin E on Resistance to Stresses in Juvenile Sea Cucumber

Sea cucumber juveniles with initial body weight of 3.46 g were stocked into 300 liter plastic tanks and fed the diets containing 90mg.kg-1β-carotene and 60mg.kg-1vitamin E(VE)(group A),or 60 mg.kg-1astaxanthin and 60 mg.kg-1VE(group B)(without supplementation as control group,group C)with triplicates at water temperature of 11.0～20.0℃,a salinity of 35,and pH 7.5 for 80 days.Then the sea cucumber juveniles being held in a 1500 mL beaker were directly exposed to abrupt changes in salinity(0,5,10,15,20,25,30,35,40,45,and 50 prepared by fresh water,sea water or crystal salts),in NH3-N(0,0.5,1.0,2.0,4.0,8.0,and 10 mg.L-1 prepared by NH4Cl),and in temperature(0,4,10,15,20,25,30,35,and 40℃)to evaluate the effects of dietary β-carotene,astaxanthin and VE on resistance to stresses in juvenile sea cucumber by monitoring survival and activity of superoxide dismutase(SOD)for 96 h.There were higher survival rates under salt stress,and ammonia stress in the sea cucumber juveniles in groups A and B than those in the control group.The survivors of the sea cucumber juveniles fed the diets containing β-carotene,astaxanthin and VE exposed to the ammonia stress showed significantly lower SOD activity than the sea cucumber in the control group did at all ammonia levels,indicating that the sea cucumber had enhanced anti-oxidation capability.But there were no significant differences in survival rate in the sea cucumber fed the diets containing β-carotene or astaxanthin and VE exposed to lower thermal stress