不同蛋白质和脂肪水平对1龄团头鲂生长性能和体组成的影响

试验采用3×3因子设计,探讨了饲料中不同蛋白质和脂肪水平对1龄团头鲂均重:(50.37±1.27)g]生长性能和体组成的影响。试验设3个蛋白质水平(25%、30%和35%)和3个脂肪水平(3%、6%和9%),共配制9组饲料。试验鱼饲养于网箱(规格为2 m×1 m×1 m)中,每天投喂3次,试验期为8周。结果表明:蛋白质和脂肪之间无交互作用存在(P>0.05)。蛋白质和脂肪水平对存活率无显著影响(P>0.05)。增重率、特定生长率和饵料系数显著受蛋白质和脂肪水平影响(P<0.05)。其中,25%蛋白组的增重率及特定生长率显著低于其他蛋白组(P<0.05),而6%脂肪组显著高于其他脂肪组(P<0.01)。尽管35%蛋白6%脂肪组的饵料系数最低,但与除了25%蛋白3%脂肪和25%蛋白9%脂肪这两组外的其他组相比,差异均不显著(P>0.05)。蛋白效率比和氮保留率随蛋白质水平的升高显著降低(P<0.05)。此外,蛋白效率比显著受脂肪水平的影响(P<0.05),以6%组最高。能量保留率随脂肪水平的升高显著升高(P<0.05)。鱼体肥满度随蛋白质和脂肪水平的升高显著升高(P<0.05)。腹脂率和肝体比随脂肪水平的升高显著升高(P<0.05),而受蛋白质水平的影响较小(P>0.05)。蛋白质水平对全鱼、胴体和肝脏的组成均无显著影响(P>0.05)。脂肪水平对全鱼水分、脂肪和能量有极显著影响(P<0.01),其中,全鱼水分含量随脂肪水平的升高显著降低(P<0.01),而脂肪和能量含量则显著升高(P<0.01)。胴体和肝脏水分、脂肪含量的变化趋势与全鱼基本一致。以上结果表明,1龄团头鲂的适宜蛋白质和脂肪水平分别为30%和6%,适宜蛋能比为18.21 g/MJ。

EFFECTS OF DIFFERENT PROTEIN AND LIPID LEVELS ON THE GROWTH PERFORMANCE AND BODY COMPOSITION OF BLUNT SNOUT BREAM (MEGALOBRAMA AMBLYCEPHALA) YEARLINGS

A 3×3 factorial design was used to determine effect of dietary protein and lipid levels on growth performance and body composition of blunt snout bream yearlings(average initial weight of 50.37±1.27 g).Nine experimental diets were formulated to contain three protein levels(25%,30% and 35%),each of which had three lipid levels(3%,6% and 9%).Fish were held in floating cages(2 m×1 m×1 m) and fed three times daily for 8 weeks.No interaction between dietary protein and lipid existed for growth performance and body composition(P>0.05).No significant difference(P>0.05) was observed in survival rate among all the treatments.Weight gain(WG),specific growth rate(SGR) and feed conversion ratio(FCR) were significantly influenced by both dietary protein(P<0.05) and lipid levels(P<0.05).WG and SGR of fish fed with 25% protein were significantly(P<0.05) lower than that of the other groups;whereas,the opposite was true for fish fed with 6% lipid(P<0.01).Although the lowest FCR was found in fish fed with 35% protein and 6% lipid,no significant difference(P>0.05) was observed among the other treatments except for that of fish fed with 25% protein + 3% lipid and 25% protein + 9% lipid.Protein efficiency ratio(PER) and nitrogen retention efficiency decreased significantly with increasing dietary protein levels(P<0.05).In addition,PER was significantly(P<0.05) affected by dietary lipid level with the highest observed in fish fed with 6% lipid.Energy retention efficiency increased significantly as dietary lipid levels increased(P<0.05).Condition factor improved significantly(P<0.05) as dietary protein and lipid levels both increased.Intraperitoneal fat ratio and hepatosomatic index increased significantly(P<0.05) as dietary lipid levels increased.No significant difference(P>0.05) was observed in body composition among all the treatments at different dietary protein levels.Moisture,lipid and energy contents of whole-body were significantly(P<0.01) affected by dietary lipid levels.Contrary to moisture content,lipid and energy contents of whole-body in-creased significantly(P<0.01) with increasing lipid level.Similar results were also observed in carcass and liver composition.The results of this study indicated that diet containing 30% protein and 6% lipid with a protein to energy ratio of 18.21 g/MJ was suitable for blunt snout bream yearlings.