Influence of dietary inosine and vitamin C supplementation on growth, blood chemistry, oxidative stress, innate and adaptive immune responses of red sea bream, Pagrus major juvenile

Both inosine (INO) and vitamin C (L-ascorbic acid, MA) play important roles in growth performance, feed utilization and health status of fish. Therefore, a 56 days feeding trial was conducted to determine the interactive effects of dietary INO and MA on growth performance, oxidative status, innate and adaptive immune responses of red sea bream. Fish growth performance and fed utilization parameters were significantly affected by dietary INO supplementation but not by AsA. Fish fed diets with INO at 4 g kg(-1) diet in combination of high and low levels of MA (3.1 g kg-1 and 9.3 g kg-1) produced the highest growth and feed utilization performances. In terms of growth and feed utilization performances no significant interaction effects were observed between INO and MA. Dietary INO significantly influenced hematocrit, glucose and glutamyl oxaloacetic transaminase (GOT) content of red sea bream meanwhile MA also significantly influenced hematocrit, glucose, total cholesterol, blood urea nitrogen (BUN) and glutamic-pyruvate transaminase (GPT) content of the test fish. No significant interaction effects was also observed between INO and MA on measured hematological parameters. Reactive oxygen metabolites (d-ROMs) significantly influenced by both INO and MA. Fish fed diet groups D1, D4 and D6 showed best oxidative stress resistance. Only INO was a significant factor on nitro-blue-tetrazolium activity (NBT) and bactericidal activity (BA). Neither INO nor MA was a significant factor on serum catalase activity (CAT), total serum protein (TSP), peroxidase activity (PA) and lysozyme activity (LA). No significant interaction effects was observed between INO and AsA on measured innate immune parameters. Agglutination antibody titer was significantly influenced by dietary supplementation, after 15 days of vaccination but not in 21 days. In the day 15th fish and diet group D3 and D5 showed significantly higher values compared to diet groups control and D1. INO was the only significant factor of increasing agglutination antibody titer in 15 t h day. While MA was not a significant factor on agglutination antibody titer values in day 15 t h, there was an interaction between dietary INO and MA levels. Finally under the experimental conditions, fish fed high INO and low MA levels (4 g kg(-1) and 0.31 g kg(-1) diet, respectively) showed best growth and feed utilization performance. Simultaneously, low level of INO and high level of MA (2 g kg(-1) and 0.93 g kg(-1) diet, respectively) improved blood chemistry and immunological parameters. Furthermore, combined use of INO and MA is possible to improve hemato-immunological responses of red sea bream.