大鲵幼体蛋白质的需求量

为评定大鲵幼体对饲料蛋白质的需求量,以鱼粉为主要蛋白源配制6种蛋白质水平(干样基础)的实验饲料:D1(43.7%)、D2(47.1%)、D3(51.3%)、D4(55.7%)、D5(59.9%)和D6(64.4%),饲喂初始体质量为(20.99±0.15)g的大鲵幼体92 d。结果显示,①饲料蛋白质水平对大鲵增重率有显著影响,在D4组达到最大值,较D1组增加了276.4%,且全鲵蛋白质沉积率和肌肉RNA、RNA/DNA值、胃蛋白酶、H^+-K^+-ATPase、胰蛋白酶、脂肪酶和Na^+-K^+-ATPase、肝脏超氧化物歧化酶(SOD)均在D4组达到最佳,而肝脏和肠道丙二醛(MDA)在该组均达到最低;②随饲料蛋白质水平增加,肌肉粗蛋白线性增加,全鲵脂肪线性下降,全鲵水分和粗灰分在各组间差异不显著,全鲵粗蛋白先增加后趋于稳定,在D4组达到最大;③大鲵皮肤胶原蛋白含量在D4组达到最高,较D1组增加了27.83%。研究表明,以增重率、肌肉RNA/DNA值、蛋白质沉积率和皮肤胶原蛋白含量为评价指标,通过二次回归方程分析得到大鲵幼体饲料的最适蛋白质水平为55.9%~58.3%(干样基础),该饲料蛋白质水平能显著提高大鲵幼体胃的泌酸能力、机体消化吸收和抗氧化能力,增加鲵体营养素的沉积,从而促进生长和饲料的转化;而低蛋白质水平饲料显著抑制大鲵的生长。

Dietary protein requirement of juvenile giant salamander (Andrias davidianus)

In order to determine the dietary protein requirement of juvenile giant salamander,6 isolipidic diets were formulated to contain graded levels of D1(43.7%),D2(47.1%),D3(51.3%),D4(55.7%),D5(59.9%)and D6(64.4%)crude protein(dry matter)to feed juvenile giant salamander with initial weight(20.99±0.15)g for 92 days.The results show that:①Dietary protein levels had significant effects on weight gain rate of giant salamander,and it reached the highest in the D4 group,which is 276.4%higher than group D1,and the whole body protein deposition rate and muscle RNA,RNA/DNA ratio,pepsin,H^+-K^+-ATPase in stomach,trypsin,lipase and Na^+-K^+-ATPase in intestine,liver superoxide dismutase(SOD)reached the best in the group D4,and the malondialdehyde(MDA)in liver and intestine were both the lowest in group D4.②The content of muscle crude protein increased linearly with the increase of dietary protein level,while the fat content in giant salamanders declined linearly,and there was no significant difference in moisture and crude ash of whole body between different groups,and whole body crude protein increased first and then tended to be stable,reached the highest in the group D4.③The skin collagen content in group D4 reached the highest,increasing by 27.8%compared with D1.With weight gain rate,muscle RNA/DNA ratio,protein deposition rate,and skin collagen content as evaluation indexes,the optimum dietary protein level of the giant salamander was 55.9%-58.3%(based on dry mater),and this dietary protein level can significantly improve gastric acid secretion,the digestion and absorption,and antioxidant capacity,and increase the nutrient deposition,thus promote growth and feed conversion;While low protein level diet significantly inhibited the growth of A.davidianus.