Effects of dietary corn gluten meal on growth, digestion and protein metabolism in relation to IGF-I gene expression of Japanese seabass, Lateolabrax japonicus

Abstract

Abstract A 60-day feeding trial in seawater floating cages (1.5 × 1.5 × 2.0 m) was conducted to investigate the effects of dietary corn gluten meal (CGM) levels on feed intake, growth performance, survival, digestion and protein metabolism in relation to IGF-I gene expression of Japanese seabass (initial body weight 18.09 ± 0.10 g). Six isonitrogenous (crude protein 43%) and isoenergetic (18 kJ g − 1 ) practical diets were formulated by replacing 0 (the control), 15, 30, 45, 60 and 75% of fish meal protein with CGM protein. Each diet was randomly fed to triplicate groups of fish, and each cage was stocked with 30 fish. Fish were fed twice daily (05:30 and 16:30) to apparent satiation. The survival rate ranged from 96 to 100%, and no significant difference was observed among dietary treatments ( P > 0.05). With increasing dietary CGM levels, feed intake (FI) and specific growth rate (SGR) decreased, however, feed efficiency (FE) showed a contrary changing trend. Fish fed the diet with 75% of protein from CGM had significantly lower SGR than the control group ( P P P P > 0.05). When the substitution level was equal to or above 15%, the activities of protein metabolism enzymes (alanine aminotransferase, ALT; aspartate aminotransferase, AST) were significantly lower compared with the control group ( P P