饲料中添加叶酸和VB12对中华绒螯蟹幼蟹生长、非特异性免疫和抗病力的影响

为研究叶酸和VB12协同作用对中华绒螯蟹(Eriocheir sinensis)幼蟹生长、非特异性免疫和抗病力的影响,选取初始体重为(2.570.03) g的幼蟹600只,随机分成4组,每组5个重复,每个重复30只幼蟹,分别投喂对照组(不添加叶酸和VB12),单一VB12组(0.2 mg/kg),单一叶酸组(2.3 mg/kg)和联合处理组(0.2 mg/kg VB12 +2.3 mg/kg叶酸)的饲料8周。在养殖实验结束后,先统计成活率和称重,然后从每个处理组随机选取30只幼蟹,用2108 CFU/mL的嗜水气单胞菌注射攻毒2周。实验结果表明:幼蟹的增重率、特定生长率、饲料效率和存活率在联合处理组最高,显著高于对照组(P0.05),但与单一叶酸或VB12组相比不存在显著差异(P0.05)。联合处理组的血清酚氧化酶活性显著高于对照组(P0.05),但与单一叶酸或VB12组也无显著性差异(P0.05)。同时,联合处理组的血清酸性磷酸酶、碱性磷酸酶、溶菌酶活性和血细胞总数等指标最高,其次是单一叶酸组和VB12组,而对照组最低。投喂联合处理组饲料幼蟹的肝胰腺超氧化物歧化酶活性最高,而丙二醛含量和累积死亡率最低。以上结果表明,叶酸和VB12对幼蟹的生长、生理代谢和免疫性能均可能有互补和协同作用,养殖生产中建议饲料中叶酸和VB12添加量分别为2.3 mg/kg和0.2 mg/kg。  

THE EFFECTS OF DIETARY FOLIC ACID AND VITAMIN B12 ON THE GROWTH PERFORMANCE,NON-SPECIFIC IMMUNITY AND THE DISEASE RESISTANCE OF JUVENILE CHINESE MITTEN CRABERIOCHEIR SINENSIS

In this study, we aimed to determine the combined effects of dietary folic acid and vitamin B12 on the growth, non-specific immunity, and the disease resistance of juvenile Chinese mitten crab Ericheir sinensis. The crabsinitial weight,(2.570.02) g were fed with 4 experimental diets containing 2 concentrations of folic acid(0 and 2.3 mg folic acid/kg diet) and vitamin B12 (0 and 0.2 mg vitamin B12/kg diet). Each diet group had 5 replicates and was fed for 8 weeks. This was followed by an Aeromonas hydrophila challenge for 2 weeks. E. sinensis fed with 2.3 mg folic acid/kg and 0.2 mg vitamin B12/kg showed significantly higher weight gain, specific growth rate, feed efficiency and survival rate than those fed without folic acid and vitamin B12 supplementation. The activity of phenoloxidase was the maximum in juveniles fed with 2.3 mg folic acid/kg and 0.2 mg vitamin B12/kg. Juveniles fed with both folic acid and vitamin B12 supplementation had the highest levels of total haemocyte count, lysozyme, and activities of acid phosphatase and alkaline phosphatase, followed by crabs fed with either folic acid or vitamin B12 only, and the group without folic acid or vitamin B12 supplementation was the lowest. Crabs fed with 2.3 mg folic acid/kg and 0.2 mg vitamin B12/kg exhibited the highest activity of superoxide dismutase but the lowest level of malondialdehyde and the cumulative mortality. These results indicated that folic acid and vitamin B12 had an interactive effect on the growth, non-specific immunity and the disease resistance of juvenile E. sinensis. The optimal concentrations of dietary folic acid and vitamin B12 should be 2.3 mg/kg diet and 0.2 mg/kg diet respectively.