维生素C对花鱼种生长和免疫指标的影响

研究了饲料中维生素C（VC）的含量对花Hemibarbus maculates鱼种生长和免疫指标的影响。在水温为（25.0±3.0）℃的条件下,将14.84 g的花鱼种放养在12个网箱（60 cm×60 cm×120 cm）中,网箱放在室外2个水泥池（6.0 m×2.0 m×1.2 m）中。试验设F0（对照）、F1、F2、F3 4组,分别投喂按0、1 000、2 000和3 000 mg/kg（饲料）剂量添加含量为95%的包膜VC的试验饲料（粗蛋白37.0%、粗脂肪11.0%）。125 d的饲养结果表明：花的成活率为93.33%-98.67%,各组间差异不显著（P〉0.05）;随着饲料中VC含量的增加,花鱼种的特殊增重率先上升后降低,摄食含973.00 mg/kg VC的饲料时（F1组）,鱼的特殊增重率显著高于其它组（P〈0.05）,饲料系数极显著低于其它组（P〈0.01）,蛋白质利用率极显著高于其它组（P〈0.01）;根据二次曲线拟合计算得出,花特殊增重率最高和饲料系数最低时,饲料中VC的含量为1 415.78-1 451.74 mg/kg;花鱼种血清中γ球蛋白含量随着饲料中VC含量的增加先升高再降低,VC含量为973.00 mg/kg时达最高值,该组极显著地高于其它组（P〈0.01）;花鱼种血清中溶菌酶和超氧化物歧化酶活性随饲料中VC含量的增加而极显著升高（P〈0.01）,分别在VC含量为2 857.00、1 882.00 mg/kg（F3、F2组）时达最大值。

Effects of dietary vitamin C levels on growth and some immune indexes in Hemibarbus maculates juveniles

A feeding trial was conducted to evaluate effects of dietary ascorbic acid （ vitamin C） on growth and some immune indexes in the juvenile Hemibarbus maculates. The juveniles with 14.84 g in initial body weight were stocked into 12 net cages of each 60 cm x 60 cm×120 cm placed in two flowing water concrete tanks of each 6.0 m×2.0 m×1.2 m at a rate of 25 individuals per cage and fed semi - purified formulated feed containing 37.0% of crude protein and 11.0% of crude lipid, and supplemented with four levels （0,1 000,2 000, 3 000 mg/kg diet） of 95% coated - ascorbic acid with triplication for each diet at a water temperature of（25.0±3.0）℃ for 125 days. The survival of the juveniles ranged from 93.33 % to 98.67% during the experiment, without significant differences among the groups （P 〉 0.05 ）. The specific growth rate （SGR） of the fish increased with increase in dietary vitamin C levels first, and then decreased. The fish fed the diets containing the vitamin C levels of 1 415.78 mg/kg and 1 451.74 mg/kg had the maximal SGR and the minimal feed conversion ratio （FCR）. The maximal serurm γ - globulin level, and activities of lysozyme and superoxide dismutase （ SOD）, very significantly different from the control group （P 〈 0.01 ）, were found in the fish fed the diets containing the vitamin C levels of 973.00,2 857.00 and 1 882.00 mg/kg, respectively. There were very significantly higher activities of protease, amylase and lipase in the hepatopancreas of Hemibarbus rnaculates fed the diets supplemented with vitamin C than those in the fish fed the diets without vitamin C supplementation （P 〈0.01 ）.