饲料蛋白质水平对刺鲃幼鱼的生长、胴体营养组成及消化酶活性的影响

配制蛋白质水平20%~50% 的7种等能半精制实验饲料，饲养平均初始体重为1.26±0.02 g 的7组3重复的刺鲃(Barbudes caldwell)幼鱼8周，研究刺鲃对饲料蛋白的需求量。结果显示,饲料蛋白水平对实验鱼的成活率、脏体比和肝体比等均无显著影响(P >0.05)，而对鱼体终重有显著影响(P <0.05)；鱼体增重和生长比速均随饲料蛋白水平从20%升高到35%而不断提高，但饲料蛋白水平进一步提高，则鱼体增重和生长比速均无显著差异(P >0.05)。饲料蛋白水平30%～50%的5个实验组的饲料效率无显著差异(P>0.05), 但均显著高于饲料蛋白为20%和25%的2个实验组(P <0.05)。蛋白质效率(PER)与饲料蛋白水平(x)呈负相关(PER= 3.006－0.03251x, R =0.9366)。饲料蛋白水平对鱼体的胴体水分、粗蛋白和粗灰分的含量无显著影响(P > 0.05)；胴体脂肪含量随饲料蛋白水平(x)的升高而不断降低(L=8.2169－0.0458x,R =0.8551)。实验鱼肝胰脏蛋白酶活性则在组间无显著差异(P > 0.05)。肠蛋白酶和肝胰脏淀粉酶活性均随着饲料蛋白水平的升高而呈现先逐渐升高，且升高到一定程度后又呈逐渐下降的趋势。肠淀粉酶活性(IAA)与饲料蛋白水平(x)呈负相关关系(IAA = 84.625－0.9147x, R =0.8463,)。以鱼体增重为指标(y)，与饲料蛋白水平(x)拟合折线模型进行回归分析，估算出饲料蛋白质适宜水平为占干饲料的34%。

Effects of Diet Protein Level on the Growth, Body Composition and Digestive Enzyme Activities of the Barbudes caldwell Juvenile

Seven isoenergic semi-purified test diets containing graded levels of protein ranging from 20% to 50% were formulated using fish meal and casein as the protein sources. Triplicate groups of Barbudes caldwell juveniles with initial body weight of 1.26±0.02 g respectively were fed by the test diets for 8 weeks. The results indicated that there was no significant effect of dietary protein levels on the survival rate, relative weight of viscera and relative weight of liver of the juvenile fish (P >0.05). The weight gain and specific growth rate of the fish were increased with dietary protein level increasing from 20% to 35% (P >0.05), but not affected significantly as dietary protein level increased from 35% to 50% (P >0.05). Feed efficiencies were not significantly different when fish fed diets with protein levels from 30% to 50%, but significantly higher than those of the other two treatments when fish fed diets with protein levels of 20% and 25% (P <0.05). The protein efficiency ratio(PER) was negatively correlated to the diet protein level(x) (PER = 3.006－0.03251x, R =0.9366). There was no significant effect of dietary protein levels on carcass moisture, crude protein and ash of the juveniles (P >0.05). While carcass lipid was decreased with the increase of dietary protein level(x) (L =8.2169－0.0458x, R =0.8551). There was no significant variation of hepato-pancreas protease activity among tests (P >0.05). Intestine protease activity and hepato-pancreas amylase activity were increased to some extent, and then decreased with continued increasing dietary protein level. The intestine amylase activity (IAA) of the juvenile was negatively correlated to dietary protein level (x) (IAA = 84.625－0.9147x, R =0.8463). It was estimated that the suitable protein level for the B. caldwell juvenile was 34% of dry diet when the broken-line model was introduced to regress the relationship of weight gain of the juvenile and dietary protein level.