大菱鲆的赖氨酸最适需求量研究

Study on the Optimal Lysine Requirement of Turbot

为研究大菱鲆(Scophthalmus maximus L.)的赖氨酸需求量,评估饲料中赖氨酸含量对大菱鲆的血浆生化指标、消化酶活性以及抗氧化和免疫功能的影响,本研究设计了5种等氮(约50%粗蛋白)和等脂(约12.5%粗脂肪)的饲料,饲料中赖氨酸含量分别为1.69%、2.49%、3.32%、4.11%和4.90%,进行了10周的饲养实验。对大菱鲆的生长性能、消化酶活性、肝脏抗氧化和免疫能力等指标进行测量。研究表明,当饲料中赖氨酸添加量增长到3.32%时,大菱鲆的生长性能逐渐提升,此后呈稳定趋势,而缺乏赖氨酸会对大菱鲆的生长和饲料利用造成不利影响。随着饲料中赖氨酸含量从1.69%增加到4.90%,全鱼粗脂肪降低、粗蛋白含量增加。此外,大菱鲆的肝体比(HSI)也随着饲料赖氨酸含量的增加而降低。在肠道消化酶活性方面,脂肪酶和胰蛋白酶表现出随饲料赖氨酸含量的增加先升高后降低的趋势,均在3.32%时活性最高。饲料中赖氨酸添加量的改变不影响血糖含量,但1.69%组和2.49%组的血浆甘油三酯(TG)和总胆固醇(T-CHO)含量显著升高。饲料中适宜的赖氨酸含量能够提高大菱鲆肝脏的抗氧化能力,并通过调节非特异性免疫,缓解炎症反应。本研究结果表明,当饲料中赖氨酸水平为饲料干质量的3.19%(饲料蛋白质的6.39%)左右时,能够最大限度地发挥赖氨酸的有效功能。

In order to optimize the lysine requirement of turbot(S cophthalmus maximus L.)and evaluate the effects of dietary lysine level on plasma biochemical indexes,digestive enzyme activity antioxidant and immune function of turbot,five isonitrogen(about 50%crude protein)and isolipid(about 12.5%crude fat)diets were designed in this study,of which the lysine contents were 1.69%,2.49%,3.32%,4.11%and 4.90%respectively,and fed for ten weeks.The results showed that when the dietary lysine content increased to 3.32%,the growth performance gradually improved,and then stabilized.Low dietary lysine content will adversely affect the feed utilization of turbot.With the increase of dietary lysine content from 1.69%to 4.90%,whole body lipid decreased and the protein increased.The liver body index(HSI)of fish also decreased with the increase of dietary lysine content.In terms of intestinal digestive enzyme activity,lipase and trypsin increased first and then decreased with the increase of dietary lysine content,reaching the highest level at 3.32%lysine.The addition of dietary lysine did not affect blood glucose content while plasma triglyceride(TG)content and total cholesterol(T-CHO)content increased significantly in 1.69%group and 2.49%group.In addition,the appropriate content of lysine can improve the antioxidant capacity of turbot liver and alleviate the inflammatory response by regulating nonspecific immunity.In this study,we found that when the dietary lysine content is about 3.19%of feed dry weight(6.39%of dietary protein),it can play its effective role to the greatest extent.