饲料脂肪水平对吉富罗非鱼生产性能、营养物质消化及血液生化指标的影响

为探讨吉富罗非鱼对脂肪的适宜需求量,将630尾(2.63±0.16)g吉富罗非鱼随机分成6个脂肪组的饲料组(1.73%、3.71%、5.69%、7.67%、9.64%和16.55%),每组设置3个重复,每个重复35尾,第1组为对照组,投喂基础日粮(含脂肪1.73%),另外5组为试验组,在基础日粮中分别添加2%、4%、6%、8%、15%的鱼油,饲养90d后测定生长、饵料系数、营养物质表观消化率及血液常规生化指标。结果显示,随着饲料脂肪水平提高,增重率和特定生长率呈现一个先上升后下降的趋势(P＜0.05),蛋白质效率极显著地提高(P＜0.01),饵料系数极显著地下降(P＜0.01)。增重率与饲料脂肪水平的二次多项式回归分析显示,吉富罗非鱼获得最高增长所需饲料的最佳脂肪水平为9.34%。饲料脂肪水平对粗蛋白表观消化率和饲料干物质表观消化率无显著影响(P>0.05),饲料脂肪水平增加显著提高了粗脂肪和磷的表观消化率(P＜0.05)。未添加鱼油的1.73%组血液中白蛋白和白球比均显著高于其他组(P＜0.05),随着饲料脂肪水平的提高,胆固醇的浓度及碱性磷酸酶的活性极显著地上升(P＜0.01)。饲料脂肪水平对血糖浓度有显著影响(P＜0.05),对甘油三酯浓度、谷丙和谷草转氨酶的活性无显著影响(P>0.05)。结果表明,饲料中的脂肪水平可以促进吉富罗非鱼对脂肪和磷的表观消化率,但是脂肪水平过高会对鱼体增重及血液生化参数产生负作用,从生产上来说吉富罗非鱼鱼种对脂肪的适宜需求量为7.67%-9.34%。  

EFFECTS OF DIETARY LIPID LEVELS ON GROWTH PERFORMANCE, NUTRIENT DIGESTIBILITY AND BLOOD BIOCHEMICAL INDICES OF GIFT TILAPIA (OREOCHROMIS NILOTICUS)

In order to determine the optimal levels of the lipid of GIFT strain Nile tilapia(Oreochromis niloticus),630 GIFT with average weight of(2.63?.16) g were divided into six groups(1.73% lipid,3.71% lipid,5.69% lipid,7.67% lipid,9.64% lipid and 16.55% lipid) randomly.One with triplication was the control group fed with basal diet(1.73% lipid),the others were the treated groups fed with basal diet(1.73% lipid) supplemented with 2%,4%,6%,8% and 15% fish oil,respectively.After rearing 90d,the growth,feed conversion ratio,nutrient apparent digestibility and blood bio-chemical parameter were determined.Results showed that,along with dietary lipid level raising,weight gain rate and specific growth rate had a trend of going up first then falling down(P0.05),protein efficiency ratio improved(P0.01) and feed conversion ratio reduced(P0.01).Second-order regression of weight gain rate on concentrations of dietary lipid indicated that the optimal dietary lipid for maximal growth of GIFT tilapia was about 9.34%.Crude protein and dry-matter digestibility had no significant effected by dietary lipid levels(P0.05).Crude lipid and phosphorus digesti-bility raised significantly with dietary lipid level increasing(P0.05).Albumin and albumin/globulin ratio in 1.73% group(this group did not added fish oil) was significantly higher than other group(P0.05).Along with dietary lipid level raising,cholesterol and alkaline phosphatase of fish serum raised significantly(P0.01).Dietary lipid level had significantly influence on blood glucose(P0.05),and there was no significantly influence on the content of triglyceride and the activities of glutamic-pyruvic transaminase and glutamic-oxaloacetic transaminase(P0.05).It indicated that the level of lipid in the dietary could improve the growth,the apparent digestibilities of crude lipid and phosphorus to some degree,but excessive amount of lipid content in the dietary may be negative effects of fish growth and immune ability in GIFT.So 7.67%-9.34% lipid of the dietary are the optimal levels of GIFT Seedlings in aquaculture.