Dietary vitamin A requirement of juvenile Chinese mitten crab, Eriocheir sinensis.

A 10-week feeding trial was conducted to determine the dietary vitamin A requirement of juvenile Chinese mitten-handed crab,Eriocheir sinensis.Casein was used as protein source,dextrin as sugar source and fish oil as lipid source,and eight semi-purified diets with 0,5 000,10 000,20 000,40 000,80 000,160 000 and 320 000 IU/Kg vitamin A were formulated respectively,and fed twice a day to triplicate groups of 30 juveniles per tank with an initial weight of(1.54±0.45) g.The results showed that vitamin A had significant effects on crab weight gain(WG),specific growth rate(SGR),FE,crude lipid and superoxide dismutase(SOD) activity.WG and SGR of the crab increased as dietary vitamin A increased up to 80 000 IU/Kg,and then decreased as vitamin A increased further.FE increased as dietary Vitamin A increased up to 40 000 IU/Kg,and then decreased as vitamin A increased.Whole body total lipid was significantly higher in crab fed 320 000 IU/Kg diet than other levels(P0.05).SOD activity in hepatopancreas fluctuates at a particular level,then decreased significantly and fluctuates at low level as vitamin A increased.There is no significant difference of total retinol contents in eyes among all treatments.These data suggest that dietary vitamin A significantly improved crab growth,increased FE,and enhanced non-specific immunity to some extent.WG and SGR analysed by the broken-line method indicated that the optimum dietary vitamin A requirement of juvenile Chinese mitten-handed crab is between 69 740-70 770 IU/Kg.