Nucleoside by-product dietary supplementation influences blood chemistry, immune response, oxidative stress resistance and intestinal morphology of juvenile amberjack, Seriola dumerili.

We explored the influence of nucleoside by-products (NBP) on blood chemistry, immune response, oxidative stress and intestinal morphology of Seriola dumerili. Four experimental diets were formulated where diets 1-3 are semipurified and supplemented with liquid NBP at concentration of 0 (D1, negative control), 30 (D2) and 90 (D3) g/kg. Diet 4 (D4) is a fishmeal-based positive control diet. Each diet was randomly allocated to triplicate groups of fish for 50 days. The results revealed a significant influence of NBP supplementations on total cholesterol, blood urea nitrogen and triglyceride level. Lysozyme activity (LA), total serum protein (TSP) and peroxidase activity (PA) also increased with NBP supplementation as compared to the negative control. TSP, PA and LA were numerically higher in diet groups D2 and D4, respectively. Anterior enterocyte height (hE) was higher in diet group D4, while NBP-supplemented groups showed intermediate values with D1 group and negative control group showed significantly lowest value. Supplementation of NBP also increased anterior fold height (hF) and microvillus height and posterior hF, hE and microvillus height compared with D1. Finally, we concluded that NBP can be used as a cheaper nucleotide/nucleoside source for amberjack. Supplementation of more than 30 g/kg in diets improved blood chemistry, non-specific immunity, oxidative stress resistance and intestinal morphology of amberjack. [ABSTRACT FROM AUTHOR]