Effects of Arginine-Deficient and Replete Diets on Growth Performance, Digestive Enzyme Activities and Genes Expression of Black Sea Bream, Acanthopagrus schlegelii, Juveniles

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Abstract

The objective of this study was to investigate the effects of black sea bream, Acanthopagrus schlegelii, juveniles fed with arginine-deficient and replete diets. One hundred and eighty fish were randomly allocated into three arginine level diets with triplicate groups: T1, 1.88% (arginine deficient diet without supplementation); T2, 2.49% (supplemented with 0.6% arginine); and T3, 3.13% (supplemented with 1.2% arginine) of dietary arginine, respectively. The results showed that the daily growth increments of fish in T1 group was significantly lower than those of fish fed T2 and T3 diets, while no significant differences were observed between two replete arginine treatments. Fish fed with replete arginine diets had higher pepsin/trypsin activities in stomach, foregut, and midgut. Amylase activities in stomach and foregut were also enhanced in the arginine groups than the T1 group. Arginine and inline image EAA content of dorsal muscle increased significantly with dietary increasing arginine levels. The relative mRNA expression levels of growth hormone receptor gene in liver and insulin-like growth factor-I (IGF-I) gene in dorsal muscle were stimulated significantly by dietary arginine supplementation, but no significant differences were observed between T2 and T3 diets. IGF-I expression in liver was markedly increased with dietary increasing arginine level. The present findings indicated that black sea bream fed with replete arginine diets could improve growth performance by enhancing pepsin/trypsin and amylase enzymes activities, as well as stimulating growth-related genes expression level.

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