Effects of arginine and/or N-carbamylglutamate supplementation on growth, biochemical composition and expression of growth-regulating factors of hybrid sturgeon (Acipenser schrenckii ♀ ×A. baerii ♂) juveniles fed an arginine-deficient diet

A 2 × 3 factorial experiment was carried out to determine the roles of arginine (Arg) and/or N-carbamylglutamate (NCG) supplemented in diet on growth, biochemical composition as well as mRNA expression levels of growth hormone/insulin-like growth factor-I (GH/IGF-I) in the hybrid sturgeon (Acipenser schrenckii ♀×A. baerii ♂) juveniles raised by the Arg-deficient diet. 30 fish pre tank was fed with each diet (Arg levels: 0% and 1%; NCG levels: 0%, 0.05% and 0.1%) for 8 weeks with three replications for each group. Fish supplemented with 0.1% NCG showed significantly increased final body weight, weight gain rate and protein efficiency ratio, whereas decreased feed conversion ratio compared with those supplemented with 0% NCG (P < 0.05). Dietary Arg or NCG reduced the body moisture but elevated the body crude lipid (P < 0.05). Body crude protein content was significantly increased by the addition of 0.05% NCG (P < 0.05). The Arg concentration of the carcass was significantly affected by dietary Arg and NCG levels (P < 0.05). Dietary NCG supplementation significantly increased the NO concentrations (P < 0.05). The hepatic nitric oxide synthase (NOS) activity in fish supplemented with 0.1% NCG significantly increased relative to that in those supplemented with 0% NCG (P < 0.05). Dietary NCG supplementation markedly increased IGF-I mRNA expression level(P < 0.05). Besides, GH mRNA expression level in 0.1% NCG groups evidently increased relative to those in 0% NCG groups. These results indicated that dietary supplementation with 1% Arg and/or 0.1% NCG could improve growth performance and increase Arg concentration and the GH/IGF-1 gene expression of hybrid sturgeon fed an Arg-deficient diet.