小肽对星斑川鲽幼鱼消化酶活性、抗氧化能力和生化组成的影响

Effects of small dietary peptides on digestive enzyme activity, antioxidative capability, and biochemical composition in tissues of juvenile starry flounder Platichthys stellatus

选用初始体质量（15.30±0.03） g的星斑川鲽（Platichthys stellatus）幼鱼,在其基础饲料中添加不同梯度的小肽（鱼水解肽）,添加水平分别为0（对照组）、0.25%、0.50%、0.75%、1.0%和1.5%,每组设3个重复,每个重复30尾鱼,实验周期为56 d。结果表明：1）除肝胰脏淀粉酶外,星斑川鲽幼鱼胃、肠和肝胰脏中消化酶活性在各组间均存在显著性差异（P〈0.05）,且随着小肽添加水平的上升而呈现先上升后下降的趋势。2）饲料中添加小肽显著降低了肝胰脏和血清中的丙二醛含量（P〈0.05）,并显著提高了1.0%和1.5%小肽添加组血清的总抗氧化能力,而对肝胰脏超氧化物歧化酶和谷胱甘肽还原酶均无显著影响（P〉0.05）,同时,1.0%和1.5%小肽添加组血清超氧化物歧化酶和谷胱甘肽氧化物酶活性以及0.75%和1.0%小肽添加组血清谷胱甘肽还原酶活性均显著高于对照组（P〈0.05）。3）小肽添加组苯丙氨酸含量均显著高于对照组（P〈0.05）,0.50%~1.5%小肽添加组亮氨酸含量也显著高于对照组（P〈0.05）,而其他氨基酸在不同小肽添加组间均无显著性差异（P〉0.05）；0.75%和1.0%小肽添加组多不饱和脂肪酸含量显著高于对照组（P〈0.05）,0.5%~1.0%小肽添加组DHA和EPA含量均显著高于对照组（P〈0.05）,而ARA在不同添加组间无显著差异（P〉0.05）。综上可知,饲料中添加适量小肽可有效提高消化酶活性和抗氧化能力,促进机体生长,并在一定程度上提高鱼肉品质。

Starry flounder （Platichthys stellatus） with initial body weight of （15.30±0.03） g were fed experimental diets supplemented with six small peptide levels of 0%（control group）, 0.25%, 0.50%, 0.75%, 1.0%and 1.5%. Three repli-cates were used for each group with 30 fish per replicate. The experiment lasted for 56 days. In addition to the amylase activities of the hepatopancreas, digestive enzyme activity in three tissues （stomach, intestine and hepatopancreas） of P. stellatus were significantly different among the groups （P〈0.05）, which showed a trend of an early increase and later decrease with the small peptide levels increasing. The small peptides significantly reduced the maleic dialdehyde （MDA） content of the hepatopancreas and serum （P〈0.05）, and increased total antioxidant capacity （T-AOC） of serum in the 1.0% and 1.5% small peptide groups. There was no significant difference in superoxide dismutase （SOD） and gluta-thione reductase （GR） of the hepatopancreas （P〉0.05）. SOD and glutathione peroxidase （GSH-Px） of serum in the1.0%and 1.5%small peptide groups, and GR of serum in the 0.75%and 1.0%groups were all significantly higher than in the control group （P〈0.05）. The phenylalanine content in the experimental groups was significantly higher than in the con-trol group （P〈0.05）, and leucine in the 0.50%–1.5%groups was higher than the control group （P〈0.05）, while no sig-nificant difference was found in other amino acid profiles （P〉0.05）.∑PUFA in the 0.75%and 1.0%groups, and DHA and EPA in the 0.50%and 1.0%groups were all significantly higher than the control group （P〈0.05）, while ARA was not affected by the small peptide supplemental levels （P〉0.05）. Overall, appropriate small peptide supplementation can effectively enhance digestive enzyme activities and antioxidative capability of P. stellatus and improve the fish quality to some extent.