晶体氨基酸替代鱼粉蛋白对半滑舌鳎稚鱼消化酶和代谢酶活力的影响

为研究人工微颗粒饲料中晶体氨基酸替代鱼粉蛋白对半滑舌鳎（Cynoglossus semilaevis Gnther）稚鱼消化酶和代谢酶活力的影响， 以晶体氨基酸混合物分别替代0%、25%、50%、75%和100%鱼粉蛋白（0%CAA、25%CAA、50%CAA、75%CAA和100%CAA）， 在25%替代水平设计棕榈酸甘油酯包被晶体氨基酸混合物组（C-25%CAA）， 配制实验微颗粒饲料。每种微颗粒饲料随机投喂三组实验鱼初始体重（0.0940.02） g， 35日龄， 每组实验鱼放养150尾， 养殖周期28d。研究结果表明， 在不包膜条件下， 各处理组的胰蛋白酶活力随替代水平的升高显著下降（P0.05）， 且包膜处理组（C-25%CAA）与全鱼粉组无显著差异（P0.05）。肠段胰蛋白酶活力与胰段胰蛋白酶活力比值随氨基酸替代水平的升高显著下降（P0.05）， 鱼粉组显著高于75%和100%处理组（P0.05）， 但与25%处理组、包膜处理组（C-25%CAA）和50%处理组无显著差异（P0.05）。各处理组淀粉酶活力随替代水平的升高显著上升（P0.05）。亮氨酸氨肽酶（LA）和碱性磷酸酶（AP）活力（肠段与刷状缘）均随替代水平的升高显著下降（P0.05）， 包膜处理组（C-25%CAA）与全鱼粉组无显著差异（P0.05）。谷丙转氨酶（GPT/ALT）和谷草转氨酶（GOT/AST）活力随替代水平的升高显著上升（P0.05）， 50%、75%和100%处理组显著高于鱼粉组、25%处理组和包膜处理组（C-25%CAA）。研究结果显示， 饲料中晶体氨基酸显著影响了半滑舌鳎稚鱼的消化酶和代谢酶活力， 而且在25%的替代水平下， 与未包膜组相比， 包膜处理组能显著促进半滑舌鳎稚鱼消化系统的发育。  

EFFECTS OF FISH MEAL REPLACEMENT WITH CRYSTALLINE AMINO ACID ON DIGESTIVE AND METABOLIC ENZYMES OF TONGUE SOLE (CYNOGLOSSUS SEMILAEVIS GNTHER, 1873) LARVAE

The study was conducted to investigate the effects of replacement of fish meal protein by crystalline amino acids on digestive enzymes and metabolism enzymes in tongue sole larvae. Five isoproteic and isolipidic diets were formulated to replace 0%, 25%, 50%, 75%, 100% fish meal (0% CAA, 25% CAA, 50% CAA, 75% CAA and 100% CAA) respectively. At the replacement level of 25%, another diet was formulated with amino acids coated with tripal-mitin (C-25% CAA). Each micro diet was randomly fed to triplicate groups of fish, and each group had 150 fish. The results showed that the activities of trypsin significantly decreased with increasing dietary crystalline amino acids, but there were no significant differences between C-25% CAA and 0% CAA (P0.05). The ratio of Trypsin(I) to Trypsin(P) significantly decreased with increasing dietary crystalline amino acids, and 0% CAA was significantly higher than 75% CAA and 100% CAA. The activities of amylase significantly increased with increasing dietary crystalline amino acids. The activities of leucine-amino peptidase and alkaline-phosphatase in intestine and purified brush border membrane of intestine significantly decreased with increasing dietary crystalline amino acids, but no significant differences were observed between C-25% CAA and 0% CAA (P0.05). Glutamic-pyruvic transaminase and Glutamic-oxalacetic trans-aminease significantly increased with increasing dietary crystalline amino acids. In conclusion, crystalline amino acids in the micro diet significantly influenced the digestive and metabolic enzymes of tongue sole larvae. In the replacement level of 25%, Comparing with 25% CAA group crystalline amino acids coated with tripalmitin (C-25% CAA) could promote the development of digestion system in tongue sole larvae.