饲料蛋白和脂肪水平对青鱼大规格鱼种生长和体组成的影响

设计5个饲料蛋白水平（30%、33%、36%、39%和42%）和2个脂肪水平（6%和9%）的52的因子试验，配制10种试验饲料，分别饲喂10组三重复平均体重为95.5 g的二龄青鱼70d，以探讨不同蛋白和脂肪水平对青鱼生长和体组成等的影响。结果表明: 鱼体增重随饲料蛋白水平从30%提高到39%不断增加（P0.05），进一步提高饲料蛋白水平至42%时，鱼体增重则不再显著变化（P0.05）；饲料系数随饲料蛋白水平从30%提高到39%而不断降低（P0.05），进一步提高饲料蛋白水平至42%时，也不再显著变化；蛋白质效率和蛋白保留率随饲料蛋白水平呈下降趋势；以鱼体增重为指标，经折线模型进行回归分析求得适宜的饲料蛋白水平为占干饲料的40%。饲料蛋白、脂肪水平及其交互作用对的试验鱼成活率均无显著差异（P0.05）。饲料脂肪水平、饲料蛋白与脂肪的交互作用对鱼体增重、饲料系数、摄食率和蛋白质效率也均无显著影响（P0.05）。摄食蛋白水平为30%和33%饲料的青鱼与摄食蛋白水平36%-42%饲料的青鱼相比，有较低的水分和较高全鱼脂肪（P0.05）。青鱼脏体比和肌肉粗脂肪含量均随着饲料中蛋白水平的提高呈降低的趋势。摄食脂肪水平为9%的饲料的青鱼较摄食脂肪水平为6%的饲料的青鱼，有较高脏体比、全鱼脂肪含量和肌肉粗脂肪含量（P0.05）。上述结果说明，青鱼摄食低蛋白和高脂肪的饲料造成过多的体脂积累。在试验条件下，青鱼大规格鱼种饲养阶段适宜的饲料蛋白和脂肪水平分别为占干饲料的40%和6%。  

EFFECTS OF DIETARY PROTEIN AND LIPID ON GROWTH PERFORMANCE AND BODY COMPOSITION OF ADVANCED FIGERLING BLACK CARP(MYLOPHARYNGODON PICEUS)

To investigate the effects of dietary protein and lipid on growth and body composition of advanced fingerling black carp (Mylopharyngodon piceus), ten trial diets for a 52 factorial experiment, formulated with five protein levels (30%, 33%, 36%, 39% and 42%) and two lipid levels (6% and 9%), were fed to triplicate groups of black carp (initial average weight 95.54 g/fish) for 70 days. We observed that weight gain increased with increasing dietary protein level up to 39% (P0.05), but did not increase further with increasing dietary protein level to 42% (P0.05). Accordingly, feed conversion ratio decreased with increasing dietary protein level from 30% to 39% and kept stable with further increasing dietary protein level to 42%; protein efficiency ratio, protein retention and viscera somatic index tended to decrease with increasing dietary protein level; analysis of weight gain data by a broken line regression model showed that the optimum dietary protein level required for the maximum growth of black carp was 40% of dry diet. Dietary lipid level and the interaction of dietary protein and lipid did not affect weight gain and feed utilization (P0.05); levels of dietary protein or lipid and their interaction did not affect the survival, body profile index, hepato-somatic index and condition factor (P0.05); fish viscera-somatic index and muscle lipid had an increasing tendency with the decrease of dietary protein level; fish fed diets with a dietary lipid level of 9% had higher whole body and muscle lipid than those of fish fed diets with a dietary lipid level of 6% (P0.05). It could be concluded that 40% dietary protein and 6% dietary lipid are suitable for maintaining good growth performance. Low dietary protein and high dietary lipid may cause extra body lipid deposition.