饲料中添加维生素C对翘嘴鲌鱼种生长及组织中抗坏血酸含量的影响

Effects of vitamin C supplement in diet on growth performance and tissue ascorbic acid levels of Culter alburnus fingerlings

在翘嘴鲌（Culter alburnus）鱼种基础饲料中添加相当于抗坏血酸含量为0mg／kg、25mg／kg、50mg／kg、100mg／kg、150mg／kg、200mg／kg和400mg／kg的包膜维生素C（Vc），制成7种实验饲料，饲养初始体质量为（3．71±0．11）g的7组翘嘴鲌鱼种8周，每个实验组包含3个重复。结果表明，摄食不添加Vc饲料的实验鱼成活率显著低于其他Vc添加组（P〈0．05）。饲料中Vc添加量为0-50mg／kg时，对鱼体增重有显著影响（P〈0．05），鱼体增重随添加量的增加而上升。但添加量继续增大，对鱼体增重不再有显著影响（P〉0．05）。饲料中维生素C添加量为。和25mg／kg时，饲料效率和蛋白质效率低于其他各组（P〈0．05）。试验饲料中Vc不同添加量对肝体指数和全鱼体成分无显著影响（P〉0．05）。肌肉中抗坏血酸含量随饲料中Vc添加量加大而不断上升，二者呈正相关关系（P〈0．05）。肝胰脏抗坏血酸含量在Vc添加量≤100mg／kg时，随饲料中Vc添加量加大而不断上升（P〈0．05），但高于此添加量时，则肝胰脏中抗坏血酸不再随添加量的上升而有显著变化（P〉0．05）。分别以鱼体增质量和肝胰脏中抗坏血酸为指标，经折线模型（Broken line model）回归分析求得翘嘴铂鱼种饲料中Vc的适宜添加量分别为53mg／kg和97mg／kg。

Culter alburnus has become a new aquaculture candidate in recent years. With the expansion of its commercial farming industry, the demand for developing cost-effective formulated feed is increasing. However, few dietary requirements of this species have been defined. Vitamin C is one of the most important essential nutrients for teleosts including Culter alburnus. The objective of this study is to evaluate the suitable level of supplemental vitamin C in a practical diet. Seven test diets containing various levele of dietary vitamin C were formulated by supplementing coated vitamin C. The levels of vitamin C equivalent supplemented in the diet were 0 mg/kg, 25 mg/kg, 50 mg/kg, 100 mg/kg, 150 mg/kg, 200 mg/kg and 400 mg/kg dry diet respectively. The diets were fed to seven fish groups in triplicate for 8 weeks. The initial body weight of the fish was （3.71 ± 0.11） g. The results showed that, the survival rate of the fish fed the diet without vitamin C supplement was significantly lower than those of other groups（ P 〈 0.05）. Weight gains of fish fed diets with vitamin C levels ranging from 0 to 50 mg/kg showed significant differences（ P 〈 0.05） and had tendency to increase with the increment of supplemented dietary vitamin C. But further increasing of dietary vitamin C supplement（to levels above 50 mg/kg dry diet） did not increase the weight gains（P 〉 0.05）. Fish fed diets with 0 and 25 mg/kg of supplemented vitamin C had significantly lower feed efficiencies and protein efficiency ratios than those in other treatments. The hepato-somatic index and whole fish body composition were not affected by dietary vitamin C（ P 〉 0.05）. Muscle ascorbic acid level increased accordingly with increasing of dietary vitamin C. Hepatopancreas ascorbic acid levels increased significantly（P 〈0.05） when the levels of dietary vitamin C increased from 0 to 100 mg/kg, and appeared to reach a plateau at the level of 100 mg/kg and higher. Broken line regression analysis of weight gain or level of hepatopancreas ascorbic acid showed that the optimum level of vitamin C was 53 mg/kg or 97 mg/kg respectively. Since some fish in 50 mg/kg vitamin C group were observed to have body deformities, which was reported to be one of symptoms of dietary vitamin C deficiency, the minimum level of vitamin C for normal growth may be lower than that required for the normal development of some specific organs of this species. For this reason, it was recommended that the suitable level of supplemental vitamin C to Culter alburnus diet be about 97 mg/kg dry diet.