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
EffectS of different protein and lipid levels on the growth performance and body composition of blunt snout bream (Megalobrama amblycephala) yearlings
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摘要: 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(P0.05)。蛋白质和脂肪水平对存活率无显著影响(P0.05)。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(P0.05)。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(P0.05), 而6%脂肪组显著高于其他脂肪组(P0.01)。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(P0.05)。蛋白效率比和氮保留率随蛋白质水平的升高显著降低(P0.05)。此外, 蛋白效率比显著受脂肪水平的影响(P0.05), 以6%组最高。能量保留率随脂肪水平的升高显著升高(P0.05)。鱼体肥满度随蛋白质和脂肪水平的升高显著升高(P0.05)。腹脂率和肝体比随脂肪水平的升高显著升高(P0.05), 而受蛋白质水平的影响较小(P0.05)。蛋白质水平对全鱼、胴体和肝脏的组成均无显著影响(P0.05)。脂肪水平对全鱼水分、脂肪和能量有极显著影响(P0.01), 其中, 全鱼水分含量随脂肪水平的升高显著降低(P0.01), 而脂肪和能量含量则显著升高(P0.01)。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。Abstract: A 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?.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? m? m) and fed three times daily for 8 weeks. No interaction between dietary protein and lipid existed for growth performance and body composition (P0.05). No significant difference (P0.05) 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 (P0.05) and lipid levels (P0.05). WG and SGR of fish fed with 25% protein were significantly (P0.05) lower than that of the other groups; whereas, the opposite was true for fish fed with 6% lipid (P0.01). Although the lowest FCR was found in fish fed with 35% protein and 6% lipid, no significant difference (P0.05) 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 (P0.05). In addition, PER was significantly (P0.05) 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 (P0.05). Condition factor improved significantly (P0.05) as dietary protein and lipid levels both increased. Intraperitoneal fat ratio and hepatosomatic index increased significantly (P0.05) as dietary lipid levels increased. No significant difference (P0.05) was observed in body composition among all the treatments at different dietary protein levels. Moisture, lipid and energy contents of whole-body were significantly (P0.01) affected by dietary lipid levels. Contrary to moisture content, lipid and energy contents of whole-body increased significantly (P0.01) 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.