Open AccessEffects of dietary tryptophan levels on growth performance, whole body composition and gene expression levels related to glycometabolism for juvenile blunt snout bream, Megalobrama amblycephala
Author(s) -
Ji K.,
Liang H.,
ChisomoKasiya H.,
Mokrani A.,
Ge X.,
Ren M.,
Liu B.
Publication year - 2018
Publication title -
aquaculture nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.941
H-Index - 79
eISSN - 1365-2095
pISSN - 1353-5773
DOI - 10.1111/anu.12684
Subject(s) - biology , feed conversion ratio , tryptophan , protein efficiency ratio , zoology , megalobrama , endocrinology , medicine , weight gain , phosphoenolpyruvate carboxykinase , biochemistry , body weight , enzyme , amino acid , gene
To investigate the effects of dietary tryptophan on growth and glycometabolism in juvenile blunt snout bream, 450 fish (initial weight 23.33 ± 0.03 g) were fed six practical diets with graded levels of tryptophan (from 0.79 g/kg to 5.96 g/kg dry matter) for 8 weeks. Results showed that final weight, per cent weight gain ( PWG ), protein efficiency rate, feed intake and feed conversion ratio ( FCR ) were significantly improved by 2.80 g/kg diet. The maximum values of protein and ash were observed in 2.80 g/kg diet, while moisture was minimum. Lipid content of fish fed 3.95 g/kg diet was significantly higher than other diets. The highest plasma insulin‐like growth factor‐1 ( IGF ‐1) content was observed in 0.79 g/kg diet. In the liver, IGF ‐1 mRNA levels were significantly downregulated by 2.80 g/kg dietary tryptophan, while glucokinase levels were by 3.95 g/kg, while glucose‐6‐phosphatase and phosphoenolpyruvate carboxykinase mRNA levels showed a converse trend compared with IGF ‐1. Based on PWG and FCR , the optimal dietary tryptophan level was determined to be 1.99 g/kg (6.20 g/kg of dietary protein) and 1.96 g/kg (6.11 g/kg of dietary protein), respectively, using broken‐line regression analysis.