大口黑鲈饲料中适宜的淀粉源及添加水平

摘要

以4种淀粉,蜡质玉米淀粉(L)、高直链玉米淀粉(Z)、小麦淀粉(X)和木薯淀粉(M),分别以5%和10%的添加量配制了8种等氮和等能(CP 48%,GE 18.5 MJ/kg)的饲料(L5、L10、Z5、Z10、X5、X10、M5和M10).用上述饲料饲养初始体重为(23.46±0.19)g的大口黑鲈45 d,以评定大口黑鲈饲料的适宜淀粉源及添加水平.结果显示,饲料中淀粉的添加水平和淀粉源对大口黑鲈的生长、饲料利用、体组成和非特异性免疫指标均有显著影响.随着同一种淀粉的添加量从5%升至10%,L10、X10和M10组实验鱼的特定生长率和摄食率显著降低,但饲料效率和蛋白质效率显著升高,而Z5和Z10组间的上述指标的差异不显著;L10、X10和M10组的肝体比、脏体比和肝糖原含量均显著升高,但Z5和Z10组间的脏体比差异不显著;全鱼和肝的脂肪含量及肝的蛋白质含量均显著降低;L10组的红细胞数和红细胞压积、Z10组的血清甘油三酯及X10组的红细胞压积和血清甘油三酯水平显著降低;Z10组的血清补体活性显著降低;L5、Z5、X5和M5组的餐后3~12 h的血糖水平各自低于L10、Z10、X10和M10组.不同的淀粉源在相同的添加量的情况下,Z5组的淀粉表观消化率和肝体比显著地低于L5、X5和M5组,而脂肪沉积率显著高于L5、X5和M5组;M5组的蛋白质表观消化率显著低于L5、Z5和X5组;Z10组的淀粉表观消化率、肝体比、脏体比和肝糖原含量显著低于L10、X10和M10组,而脂肪沉积率显著高于L10、X10和M10组;M10组的蛋白质表观消化率显著低于L10、Z10和X10组.饲料中淀粉的添加水平和淀粉源对大口黑鲈的摄食率、特定生长率、蛋白质消化率、脂肪沉积率、肝体比、肝糖原含量、红细胞数、血清甘油三酯含量和血清补体活性均有显著的交互作用.本研究表明,饲料的淀粉源和水平对大口黑鲈的生长、体组成、血液学指标、餐后血糖和非特异性免疫指标均有不同程度的影响,饲料中添加5%的蜡质玉米淀粉、高直链玉米淀粉、小麦淀粉和木薯淀粉均无妨碍,但添加10%的淀粉水平唯有高直链玉米淀粉较为合适.%Eight iso-nitrogenous and iso-energetic (crude protein, 48% and gross energy, 18.5 MJ/kg) diets (L5, L10, Z5, Z10, X5, X10, M5, and M10) were formulated with 5% and 10% waxy corn starch (L), high-amylose corn starch (Z), wheat starch (X), and cassava starch (M) to determine a suitable starch source and supplementa-tion level for a largemouth bass,Micropterus salmoides, diet. Fish (initial body weight, 23.46 g± 0.19 g) were fed to apparent satiation twice daily for 45 d. The results showed that the supplemented dietary starch level and starch source had significant effects on growth, feed utilization, body composition, and non-specific immunological in-dices of largemouth bass. Significant decreases in specific growth rate and feed intake were observed with in-creasing content of the same starch from 5% to 10%. However, feed and protein efficiency increased significantly in the L10, X10, and M10 groups, compared with those in the L5, X5 and M5 groups, whereas no differences were detected in these parameters between the Z5 and Z10 groups. Hepatosomatic index, viscerosomatic index, and liver glycogen concentration increased significantly in the L10, X10, and M10 groups, compared with those in the L5, X5, and M5 groups, but no difference was found in the viscerosomatic index between the Z5 and Z10 groups Whole-body and liver lipid contents, as well as liver protein content decreased significantly when any of the sup-plemented starches were increased from 5% to 10% in the diets. Blood erythrocyte count and hematocrit in the L10 group, serum triglyceride content in the Z10 group, and hematocrit and serum triglyceride content in the X10 group decreased significantly, compared with those in the L5, Z5, and X5 groups. Serum 50% hemolytic comple-ment (CH50) activity was significantly lower in the Z10 group than that in the Z5 group. Serum glucose concentra-tions from 3 to 12 h after a meal in the L5, Z5, X5, and M5 groups were lower than those in the L10, Z10, X10, and M10 groups. Apparent digestibility of the dietary starch and hepatosomatic index were significantly lower in the Z5 group compared with those in the L5, X5, and M5 groups, whereas whole-body lipid deposition rate in-creased significantly. Apparent digestibility of dietary protein was significantly lower in the M5 group than that in the L5, Z5, and X5 groups. Apparent digestibility of dietary starch, hepatosomatic index, viscerosomatic index, and liver glycogen concentration decreased significantly in the Z10 group compared with those in the L10, X10, and M10 groups, whereas whole-body lipid deposition rate increased significantly. Apparent digestibility of die-tary protein was significantly lower in the M10 group than that in the L10, Z10, and X10 groups. Significant in-teractions were detected between feeding rate, specific growth rate, protein digestion rate, lipid deposition rate, hepatosomatic index, glycogen content, erythrocyte count, serum triglyceride level, and serum CH50 activity be-tween the dietary starch supplementation level and starch source. In conclusion, the starch source and supplemen-tation level in the largemouth bass diet exerted different effects on growth performance, body composition, hema-tological parameters, non-specific immunological indices, and serum glucose. Adding 10% high-amylose corn starch was the most appropriate supplement in the diet for largemouth bass.