饲料不同淀粉水平对团头鲂成鱼生长性能、消化酶活性及肌肉成分的影响

为探讨饲料淀粉水平对团头鲂成鱼生长、消化酶活性和肌肉成分的影响,选用初始均重为(161±2.7)g的团头鲂成鱼360尾,随机分成6组(每组3个重复),分别投喂含淀粉17.1%、21.8%、26.4%、32.0%、36.3%和41.9%的等氮等脂饲料9周。结果发现,团头鲂成鱼成活率和特定生长率不受饲料淀粉水平影响,但饲料添加适量淀粉能提高饲料和蛋白利用率,淀粉水平对肝脏和肠道中的总蛋白酶和纤维素酶活性不产生影响,却显著影响淀粉酶活性。肝体比、肝糖原和肌肉粗脂肪含量随饲料淀粉含量的增加而显著增加,血清血糖、胆固醇和甘油三酯含量不受饲料淀粉水平的显著影响,饲料中添加过量淀粉显著降低了血清补体3和补体4含量。以蛋白质效率和饲料效率为评价指标,经折线模型回归分析,得到团头鲂成鱼饲料中淀粉的适宜添加量分别为饲料干重的34.1%和31.4%,但考虑到血清补体的活性,团头鲂成鱼日粮淀粉水平不应超过36.3%。

Effects of dietary starch levels on growth performance,digestive enzyme activities and muscle composition of adult blunt snout bream (Megalobrama amblycephala)

A 9-week feeding trial was conducted to assess the effect of dietary starch level on growth performance,digestive enzyme activities and muscle composition of adult blunt snout breaminitial weight(161±2.7)g].Six isonitrogenous and isolipidic diets were formulated with increasing starch inclusion from 17.1 to 41.9%.At the end of the feeding trial,survival rate and specific growth rate were not affected by dietary starch level.Feed efficiency rate(FER)and protein efficiency ratio(PER)were enhanced by increasing dietary starch supplementation.Dietary starch levels did not affect total protease activities in the liver and intestine,while up-regulated amylase activities.Cellulase activities were detected in the intestine and there were no significant differences among treatments.Hepatosomatic index,liver glycogen and muscle crude lipid contents were significantly increased with the increasing dietary starch levels.Similar serum glucose,total cholesterol and triglyceride contents were observed among the treatments.However significantly lower serum complement 3 and 4 contents were observed in fish fed the highest starch diet(41.9%)compared with those fed with 17.1 or 21.8% starch diets.In conclusion,the 41.9% dietary starch level gave no negative effect on growth of adult blunt snout bream,and considering the serum complement activities,the dietary starch level should not exceed 36.3% for adult blunt snout bream.On the basis of PER and FER,the optimum dietary starch requirement of adult M.amblycephala was estimated to be 34.1% of diet and 31.4% of diet,respectively,using broken-line regression analysis.