Effects of dietary glutamine on survival, growth performance, activities of digestive enzyme, antioxidant status and hypoxia stress resistance of half-smooth tongue sole (Cynoglossus semilaevis Günther) post larvae

Abstract

Abstract A 30-day feeding trial was conducted to evaluate the effects of dietary glutamine supplementation on survival, growth performance, activities of digestive enzyme, antioxidant abilities and hypoxia stress tolerance of larval half-smooth tongue sole, Cynoglossus semilaevis (35 days after hatching, 10.64 ± 0.86 mg). Four isonitrogenous and isolipidic experimental diets were formulated with supplementation of graded levels (0.0, 0.5, 1.0 and 2.0% dry diet) of glutamine (with free dietary glutamine estimated to be about 0.03, 0.46, 0.91, 1.73% dry diet), and were randomly assigned to triplicate groups of post larvae (150 post larvae per tank) to apparent satiation five times daily. The results indicated that, survival and growth performance of fish fed all glutamine-supplemented diets were significantly increased compared to the control group (P 0.05). Fish fed diets supplemented with 0.5–2.0% glutamine showed significantly higher GPX expression and lower CAT expression than those in fish fed the control diet (P C. semilaevis post larvae through improving activities of digestive enzyme, enhancing antioxidant abilities and hypoxia stress resistance. The optimal dietary free glutamine level based on SGR for C. semilaevis post larvae in the present study was estimated to be approximately 0.63% dry diet. Statement of relevance The present study mainly investigated effects of dietary glutamine on growth performance, antioxidant ability and stress resistance of half-smooth tongue sole ( Cynoglossus semilaevis ) post larvae. Our findings have showed that dietary glutamine could improve growth performance of C.semilaevis post larvae, and for the first time revealed that dietary glutamine could modulate gene expression of antioxidant enzymes in C. semilaevis post larvae. The results are reliable and of both theoretical and practical importance. The work described has not been submitted elsewhere for publication, in whole or in part, and all the authors listed have approved the manuscript that is enclosed.I have read and have abided by the statement of ethical standards for manuscripts submitted to Aquaculture.