斑点叉尾鲖对不同形式赖氨酸利用的比较研究

为比较斑点叉尾鲖(Ictalurus punctatus)对不同形式赖氨酸的利用效果, 设置了鱼粉含量5%、豆粕含量15%的正对照饲料, 及鱼粉含量2.5%、豆粕含量0的负对照饲料, 在负对照饲料基础上, 分别添加晶体赖氨酸盐酸盐、晶体赖氨酸硫酸盐以及微囊赖氨酸盐酸盐, 使其赖氨酸含量达到与正对照饲料一致的水平, 共配制5组等氮等能饲料, 饲养平均体重为(54.40.1) g的斑点叉尾鲖60d, 考察不同形式赖氨酸对斑点叉尾鲖生长、血清生化指标和蛋白质消化酶活性的影响。结果表明, 与负对照组相比, 添加晶体赖氨酸盐酸盐和晶体赖氨酸硫酸盐对斑点叉尾鲖的生长性能影响不显著(P0.05), 而添加微囊赖氨酸盐酸盐提高斑点叉尾鲖增重率20.7% (P0.05), 降低饲料系数16.0% (P0.05), 在增重率与饲料系数方面达到与正对照组基本一致的水平(P0.05)。与负对照组相比, 在饲料中添加晶体赖氨酸盐酸盐、晶体赖氨酸硫酸盐以及微囊赖氨酸盐酸盐对血清谷丙转氨酶、谷草转氨酶、碱性磷酸酶及肠蛋白酶活性的影响均不显著(P0.05), 但显著提高了胃蛋白酶活性(P0.05)。此外, 添加微囊赖氨酸盐酸盐还显著提高了肝胰脏蛋白酶活性(P0.05)。上述结果表明, 在低赖氨酸实用饲料中补充晶体赖氨酸盐酸盐或赖氨酸硫酸盐对斑点叉尾鲖的生长性能改善作用不显著(P0.05), 而补充微囊赖氨酸盐酸盐则能显著提高斑点叉尾鲖增重率, 降低饲料系数。

COMPARATIVE STUDY ON THE UTILIZATION OF DIFFERENT LYSINE SOURCES BY CHANNEL CATFISH (ICTALURUS PUNCTATUS)

The present study was conducted to compare the utilization of dietary crystalline L-lysine hydrochloride (Lys-HCl), crystalline L-lysine sulphate (Lys-H2SO4) and microcapsulated L-lysine hydrochloride (microcapsulated Lys) by the channel catfish (Ictalurus punctatus). Five diets with iso-nitrogen and iso-energy were designed including the positive control (5% fish meal, 15% soybean meal), the negative control (2.5% fish meal, 0 soybean meal). Crystalline Lys-HCl (Lys-HCl diet), crystalline Lys-H2SO4 (Lys-H2SO4 diet) and microcapsulated Lys-HCl (microcapsu-lated Lys diet) were added into the negative control to from the other 3 diets with the same level of Lys as in the positive control. We then gave the five diets to the channel catfish with an initial body weight of (54.40.1) g for 60d, in order to investigate their effects on the growth performance, the serum biochemical indices and the activities of the protein digestive enzymes. Compared to the negative control, the addition of dietary crystalline Lys-HCl or Lys-H2SO4 did not generate significant difference on the growth performance (P0.05). However, fish fed with microcapsulated Lys showed a higher weight gain rate (WGR) (+20.7%) and a lower feed conversion ratio (FCR) (-16.0%) (P0.05) than those fed with negative control diet, and their WGR and FCR were close to the positive control group. Compared to the negative control, Lys-HCl, Lys-H2SO4 or microcapsulated Lys did not significantly affected the activities of serum alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and intestine protease (P0.05), but did increase the activity of protease in the stomach (P0.05). Dietary microcapsulated Lys also significantly increased the activity of protease in the hepatopancreas. These results suggested that adding microcapsulated Lys but not crystalline Lys-HCl or Lys-H2SO4 into the low-Lys diet could improve the growth performance of the channel catfish.