【摘要】 研究了饲料中添加不同水平柠檬酸 (0 .1%、0 .2 %、0 .3%、0 .4 % )对奥尼罗非鱼 (Oreochromisniloticus×O .aureus)幼鱼 (初始平均体重约 2 .0g)生长、饲料利用、体成分和消化酶活性的影响。共设 5组试验饲料 ,每一饲料组设 3个重复水族箱 ,每箱随机放鱼 15尾 ,投喂率为 6 % ,自然光周期 ,循环过滤水系统饲养 9周 ,每周称重 1次并相应调节投喂量。结果表明 :随着柠檬酸添加量的增大 ,饲料pH值呈下降趋势 ;添加 0 .2 %柠檬酸的试验组罗非鱼的特定生长率显著高于对照组 (P <0 .0 5 ,LSD多重比较 ,下同 ) ;饲料效率在 0 .3%柠檬酸组显著高于对照组 (P <0 .0 5 ) ;罗非鱼血清葡萄糖含量在0 .4 %组显著低于对照组、0 .1%组和 0 .3%组 (P <0 .0 5 ) ;0 .2 %组和 0 .3%组血清甘油三酯含量最高 ,但组间差异不显著(P >0 .0 5 ) ;全鱼水分、粗蛋白、粗脂肪和灰分含量在组间差异不显著 (P >0 .0 5 ) ;胃蛋白酶、胰蛋白酶和肠蛋白酶活性随柠檬酸添加量增加呈先上升后下降的趋势 ,0 .2 %组的最高 ,但组间差异不显著 (P >0 .0 5 ) ;肝胰脏和肠淀粉酶活性分别在 0 .2 %和 0 .3%组最高 ,组间差异亦不显著 (P >0 .0 5 )。结果提示 ,饲料中适量添加柠檬酸 ,能提高罗非鱼幼鱼消化酶活性 ,提高饲料利用率 ,促进罗非鱼生长更多还原

【Abstract】 A 9-week feeding experiment was conducted to investigate the effects of different levels of citric acid supplement on growth, feed utilization, body composition and digestive enzymatic activities in juvenile hybrid tilapia Oreochromis niloticus×O. aureus (average body weight was about 2.0 g). The basal diet was applied as control, in which 0.1%, 0.2%, 0.3%, 0.4% of citric acid were added into basal diets as test diets, respectively. Each test diet was applied for triplicate tanks and 15 fish were stocked randomly in each tank. Feeding rate was 6% (wet body weight). The fish were reared in part of recirculating filtrated water system under natural photoperiod and collectively weighed every week. Daily rations were adjusted accordingly. The results showed that dietary pH values accordingly decreased with the increment of citric acid supplement. Significantly higher ( P<0.05) specific growth rate and feed efficiency were observed in the fish fed diets with 0.2% and 0.3% of cirtic acid, respectively. The concerntration of serum glucose in the fish fed diet with 0.4% citric acid was significantly lower than those fed basal diet and diets with (0.1%) and 0.3% of cirteic acid. The concerntrations of serum triglyceride in fish fed diets with 0.2% and 0.3% of citric acid were the highest. However, the differences among the treatments were not significant (P>0.05). No significant differences of moisture, crude protein, crude lipid and ash in whole body were observed among the treatments. The activities of pepsin, trypsin and intestinal protease showed an increasing and then decreasing trend with the increment of citric acid supplement, which were the highest in (0.2%) group. However, no significant differences were observed among the treatments. The amylase activities in hepatopancreas and intestine were the highest in 0.2% and 0.3% groups, respectively. However, significant differences were not observed among treatments. The results suggest that certain levels of dietary citric acid supplements increase the digestive enzymatic activities and feed utilization, and growth of juvenile tilapia subsequently, and have no reverse effect on nutritional composition of whole fish body.更多还原