Effects of dietary isoleucine levels on activities of digestive enzymes and immune index of Trachinotus ovatus

• Published in: Nanfang shuichan kexue Vol. 13; no. 1
• Main Authors: Huang, Zhong, Zhou, Chuanpeng, Lin, Heizhao, Tan, Xiaohong, Peng, Jingshu, Zhou, Wenchuan, Zhao, Shuyan, Qi, Changle
• Format: Journal Article
• Language: English
• Published: 01.02.2017
• Subjects: Ovatus; Trachinotus ovatus
• ISSN: 2095-0780

We investigated the effects of dietary isoleucine on the digestive enzymes and immune index of juvenile golden pompano,Trachinotus ovatus. Six diets with different concentrations of L-isoleucine( 13. 2 g[middot]kg~(-1),15. 7 g[middot]kg~(-1),18. 2 g[middot]kg~(-1),20. 7 g[middot]kg~(-1),23. 2 g[middot]kg~(-1)and 25. 7 g[middot]kg~(-1)dry diet) were formulated to contain 430 g[middot]kg~(-1)crude protein with fish meal,soybean meal,peanutmeal and pre-coated crystalline amino acids. Each diet was randomly assigned to triplicate treatments of 20 fish [initial body weight was( 6. 36 + or - 0. 03) g] for eight weeks. The intestinal amylase and pepsase activities,serum T-AOC and LZM activities,Ig M concentrations increased with increasing isoleucine concentration up to 18. 2 g[middot]kg~(-1),whereas decreased in the groups exceeding 20. 7 g[middot]kg~(-1)isoleucine significantly. Those parameters of the fish fed with diets of 15. 7 g[middot]kg~(-1)and 23. 2 g[middot]kg~(-1)isoleucine were significantly higher than those fed with diets of 13. 2 g[middot]kg~(-1)and 25. 7 g[middot]kg~(-1)isoleucine,while significantly lower than groups containing 18. 2 g[middot]kg~(-1)and20. 7 g[middot]kg~(-1)isoleucine. There is an opposite change trend in serum urea and MDA concentration,i. e.,significantly lower in 18. 2g[middot]kg~(-1)and 20. 7 g[middot]kg~(-1)isoleucine groups than those in the other groups. The SOD activity rate increased with increasing isoleucine concentration up to 18. 2 g[middot]kg~(-1),and there was no significant difference when the dietary isoleucine exceeded 18. 2 g[middot]kg~(-1). So diet with 18. 2 ~ 20. 7 g[middot]kg~(-1)isoleucine can improve the digestive performance and immune function of T. ovatus.