中华绒螯蟹幼蟹维生素C营养需求研究

Studies on vitamin C requirements of the juvenile crab (Eriocheir sinensis)

在每100g等氮、等能纯化饲料中分别添加0，100，200，400，800，1000mg维生素C(Vc)多聚磷酸酯(LAPP)，用这样配制成的试验饲料饲喂已淡化5d的河蟹大眼幼体及后续幼蟹25d，探讨Vc对大眼幼体和幼蟹生长、存活、蜕壳频率及抗逆性的影响，同时探明幼蟹对Vc的适宜需求量，结果表明，饲料Vc添加量为100-400mg／100g时，可以保证幼蟹正常生长、存活和蜕皮，尤其以投喂添加Vc200mg／100g(C2组)和400mg／100g(C3组)饲料的Ⅲ期幼蟹增重率、存活率和平均蜕皮频率较高，其中C2组(上述各指标值)分别为516．18％，62．83％，2．58，C3组分别为458．89％，66．17％，2．61；饲料中缺少Vc时(如C0组)，Ⅲ期幼蟹的增重率、存活率和平均蜕皮频率最低，分别为265．31％，26．67％和2．26．饲料中Vc的添加量达到800mg／100g(C4)和1000mg／100g(C5)时，幼蟹的蜕皮反而受到抑制，平均蜕皮频率降低，蜕皮周期延长，且存活率降低，到Ⅲ期幼蟹的增重率、存活率和平均蜕皮频率在C4组分别为355．7％，31．33％，2．39，在C5组分别为307．53％，28．56％，2．19．此外，各处理组幼蟹对抗逆性影响的试验表明，在一定的范围内，饲料中添加Vc能提高幼蟹的耐低氧能力和耐pH突变能力，而对耐盐度突变能力没有明显的影响．综合上述结果可以得出，为保持幼蟹良好生产性能，饲料中添加的Vc应为200-400mg／100g．

L-ascorhyl-2-polyphosphate (LAPP) was used as a vitamin C source to study the dietary Vc requirements of the juvenile crabs, Eriocheir sinensis. A cultured trial for 25 d was performed using six levels of LAPP at (0(C_0),100(C_1),200(C_2)),400(C_3),800(C_4) and (1 000 mg)/(100 g(C_5)) diet in isonitrogen and isoenergy purified diets. Each treatment was run in triplicate. The results show that the normal growth, survival and ecdysis of the juvenile crabs were maintained when purified diets were supplemented with (100)～(400 mg)/(100 g) diet vitamin C.The weight growth rate, survival rate and average molt frequency of juvenile crabs at Stages Ⅱand Ⅲ fed with C_2 and C_3 are higher than those of crabs fed with C_0, C_1, C_4 and C_5. In the range from (200 mg)/(100 g) diet to (400 mg)/(100 g) diet, the weight growth rate, survival rate and ecdysis frequency of the juvenile crabs at Stages Ⅱ and are Ⅲ are increased with increase of vitamin C content, when juvenile crabs at Stage Ⅲ fed with C_2 and C_3, the results are 516.18%, (458.89%), 62.83%, 66.17%, 2.58 and 2.61 respectively. Performance of juvenile crabs at Stage Ⅲ are significantly reduced by feeding Vc-deficient diets. Those data of the C_0 are 265.31%, 26.67% and 2.26 respectively. Diets that are excessively supplemented in Vc do not perform better. When diets were supplemented Vc at (800)～(1 000 mg)/(100 g) diet,the weight growth rate, survival rate and ecdysis frequency of the juvenile crabs at Stages Ⅱ and Ⅲ are lowered. The results of the juvenile crabs evaluations at Stage Ⅲ are 355.7%, (307.53%), (31.33%), 28.56%, 2.39 and 2.19 respectively. The anti-stress trial results also demonstrate that when the juvenile crabs fed with the diets supplemented with Vc their ability to endure hypoxia and pH saltation was enhanced(P<0.05). However the Vc levels do not show significant effects on tolerance for salinity saltation of the juvenile crabs (P>(0.05)). In conclusion, The optimal vitamin C levels for juvenile crabs are 200～400 mg/100 g diet. Vitamin C can also increase the anti-stress abilities of juvenile crabs.