实用饲料中补充铜对斑点叉尾生长和体色的影响

在实用饲料(含铜11.1 mg/kg)中分别添加0(对照)、5、10、20和40 mg/kg铜以五水硫酸铜(CuSO_4·5H_2O)形式],制成5种试验饲料,投喂平均体重为(98.1±0.5)g的斑点叉尾42 d,研究实用饲料中补充铜对斑点叉尾生长和体色的影响。每种饲料设3个重复,每个重复放养20尾鱼。结果表明:与对照组相比,饲料中添加10 mg/kg铜显著提高了鱼体的增重率(P0.05),显著降低了饲料系数(P0.05);饲料铜添加量进一步增加到40 mg/kg,鱼体的增重率则较添加量为10 mg/kg时显著降低(P0.05),同时饲料系数显著升高(P0.05)。肝脏和骨骼铜含量随着饲料中铜添加量的增加而上升,其中20、40 mg/kg铜添加组的肝脏铜含量显著高于对照组和5 mg/kg铜添加组(P0.05),40 mg/kg铜添加组的骨骼铜含量也显著高于对照组(P0.05),而肌肉铜含量保持基本不变(P0.05)。饲料中添加0~40 mg/kg铜对斑点叉尾背部皮肤、肌肉色度值、总叶黄素含量及背部皮肤酪氨酸酶活性均未产生显著影响(P0.05)。各组血清天门冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)活性和总胆红素(T-Bil)含量以及肌肉水分、粗蛋白质、粗脂肪和粗灰分含量无显著差异(P0.05)。10 mg/kg铜添加组具有最高的血清铜锌-超氧化物歧化酶(Cu,Zn-SOD)活性,显著高于其他各组(P0.05),而其他各组间则无显著差异(P0.05)。综上,在本试验条件下,斑点叉尾实用饲料中铜的添加量建议为10 mg/kg(饲料铜含量实测值为20.2 mg/kg)。

Effects of Practical Diet with Copper on Growth and Body Color of Channel Catfish

In the present study, copper (as the form of CuSO4· 5H2O) with the levels of 0 (control), 5, 10, 15 or 20 mg/kg were supplemented in a practical diet which contained 11.1 mg/kg copper to formulate five experimental diets to evaluate the effects of practical diet with copper on growth and body color of channel catfish ( Ictalurus punctatus) .The five experimental diets were fed to channel catfish with the average body weight of (98.1 ±0.5) g for 42 d.Each diet had 3 replicates, and each replicate had 20 fish.The results showed that weight gain rate was significantly increased and feed conversion ratio was significantly decreased by the supplementation of 10 mg/kg copper when compared with control group ( P<0.05) , but with the copper supplemental level increased to 40 mg/kg, the weight gain rate was significantly decreased and the feed con-version ratio was significantly increased compared with 10 mg/kg group ( P<0.05) .The copper content in liv-er and bone was increased with the increase of dietary copper supplemental level, the liver copper content in 20 and 40 mg/kg groups was significantly higher than that in control group and 5 mg/kg group (P<0.05), and the bone copper content in 40 mg/kg group was significantly higher than that in control group ( P<0.05), while the muscle copper content showed no significant difference among all groups ( P>0.05 ) .The chroma values and total xanthophylls content of dorsal skin, muscle and tyrosinase activity of dorsal skin of channel catfish were not significantly affected by 0 to 40 mg/kg copper supplementation ( P>0.05 ) .Serum aspartate aminotransferase ( AST) , alannine aminotransferase ( ALT) activities and total bilirubin ( T-Bil) content, and muscle moisture, crude protein, ether extract and ash contents were not significantly different among all groups ( P>0.05) .The activity of serum copper, zinc-superoxide dismutase in 10 mg/kg group was the highest, and significantly higher than that in other groups (P<0.05), but no significant difference was found among other groups ( P>0.05) .Base on results above, the optimal copper supplementation in the practical diet is suggested to be 10 mg/kg for channel catfish under this experimental condition, and the measured value of dietary copper content is 20.2 mg/kg.