Dietary Vitamin A,D₃ And K₃ Requirement Of Juvenile Chinese Mitten Crab, Eriocheir Sinensis

Chinese mitten crab(commonly known as crab) is a kind of Chinese unique aquatic product,renowned at home and abroad,which is our high-quality aquatic products in bulk.Breakthrough in crab's artificial propagation promoted various forms of aquaculture technology,and greatly promoted the development and production of artificial crab feed.Feed is the basis of aquaculture industry,and nutritional requirement and nutritional physiology is the basis for feed industry.Compared with fish,shrimp and other aquatic animals,crab nutrition research and artificial feed development is still in its infancy,especially vitamin nutrition research.The purpose of this paper is to analyse fat-soluble vitamins A,D₃ and K₃ requirement of juvenile Chinese mitten crab.1.Dietary vitamin A requirement of Chinese mitten crab juvenile, Eriocheir sinensisA 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,eight semi-purified diets with 0,5000,10000,20000,40000,80000,160000 and 320000 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±0.45g.The results showed that vitamin A had significant effects on crab weight gain(WG),specific growth rate(SGR),feed efficiency(FE),crude lipid and superoxide dismutase(SOD) activity.WG and SGR of the crab increased as dietary vitamin A increased up to 80000 IU/Kg,and then decreased as vitamin A increased further.Feed efficiency(FE) increased as dietary VA increased up to 40000 IU/Kg,and then decreased as vitamin A increased.Whole body total lipid was significantly higher in crab fed 320000 IU/Kg diet than other levels(P＜0.05).Superoxide dismutase(SOD) activity in hepatopancreas fluctuates at a particular level,then decreased significantly and fluctuates at low level as vitamin A increased.There was 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 an optimum dietary vitamin A requirement of juvenile Chinese mitten-handed crab is between 69740-70770IU/Kg.2.Effects of vitamin A on the organizational structure and ultrastructure of Chinese mitten crab's compound eyeUsing Tissue Slicing and Transmission-Electron-Microscope(TEM) to study the effects of dietary vitamin A levels on the organizational structure and ultrastructure of Chinese mitten crab's compound eye.Tissue Slicing showed different vitamin A levels in diet did not have significant effect on the organizational structure of juvenile Chinese mitten crab's compound eye.TEM results showed that lacking vitamin A in the diet(0IU/kg) led to color dilute of pigment granules in retinula cell and even lysis, pigment granules play an important role in the visual function of Chinese mitten crab; Multivesicular body is formed by a large number of small vesicles surrounded by capsule,Plate membrane body is secondary lysosome.Adding too much vitamin A (320000IU/kg) in the diet result in increasing number of small vesicles and plate membrane body in the cytoplasm surrounding the rhabdom,and found the rupture of multivesicular body.3.Dietary vitamin D₃ requirement of Chinese mitten crab juvenile, Eriocheir sinensisA 9-week feeding trial was conducted to determine the dietary vitamin D₃ 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,seven semi-purified diets with 0,400,2000,10000,50000,100000 and 200000 IU/Kg vitamin D₃ were formulated respectively,and fed twice a day to triplicate groups of 30 juveniles per tank with an initial weight of 1.45±0.11g.The results showed that vitamin D₃ had no significant effects on growth and survival,but had significant effect on body biochemical composition.Crude lipid decreased significantly as dietary vitamin D₃ levels increased,and as hepatopancreas is the main fat storage site, its lipid content also showed a similar trend.Ash increased significantly as vitamin D₃ levels increased.Vitamin D₃ can promote the deposition of calcium in the body,and crabs feed 50000-200000IU/kg vitamin D₃ diet had significantly higher body calcium content than those feed 0-400IU/kg vitamin D₃ diet.Serum inorganic phosphorus concentration increased as dietary vitamin D₃ increased up to 10000 IU/Kg,and then decreased as vitamin D₃ increased.These data suggest that dietary vitamin D₃ significantly promote the accumulation of minerals including calcium in the body and enhanced the absorption of inorganic phosphorus.Serum inorganic phosphorus concentration analysed by broken-line method indicated that an optimum dietary vitamin D₃ requirement of juvenile Chinese mitten-handed crab is 90139.40IU/Kg.4.Dietary vitamin K₃ requirement of Chinese mitten crab juvenile, Eriocheir sinensisA 9-week feeding trial was conducted to determine the dietary vitamin K₃ 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,seven semi-purified diets with 0,5,10,20,40,80 and 160 mg/Kg vitamin K₃ were formulated respectively,and fed twice a day to triplicate groups of 30 juveniles per tank with an initial weight of 1.50±0.13g.The results showed that vitamin K₃ had significant effects on crab weight gain(WG) and specific growth rate(SGR).WG and SGR of the crab increased to 64.50%and 0.79%/d respectively as dietary vitamin K₃ increased up to 10mg/Kg.,and then decreased as vitamin K₃ increased further. Vitamin K₃ had no significant effect on calcium and phosphorous metabolism,and body calcium,body phosphorus content and serum calcium,serum phosphorous concentration were not subjected to the addition of vitamin K₃,but serum alkaline phosphatase activity increased as dietary K₃ increased up to 80mg/kg,and then decreased as vitamin K₃ increased further.Feeding group without vitamin K₃ blood clotting time was significantly longer then other vitamin K₃ adding groups.These data suggest that dietary vitamin K₃ significantly improved crab growth,enhanced the activity of serum alkaline phosphatase and maintained hemolymph clotting time in the framework of normal.WG and SGR analysed by the broken-line method indicated that an optimum dietary vitamin K₃ requirement of juvenile Chinese mitten-handed crab is 16.54mg/kg-16.93mg/kg.