Dietary cytidine monophosphate enhances the growth, blood characteristics, innate and adaptive immune functions and stress resistance of juvenile red sea bream, Pagrus major

The present study was designed to evaluate the effects of dietary cytidine monophosphate on growth, blood characteristics, innate and adaptive immune functions and stress resistance of juvenile red sea bream, Pagrus major. A semi-purified basal diet supplemented with 0% (Control), 0.1% (CMP-0.1), 0.2% (CMP-0.2), 0.4% (CMP-0.4) and 0.8% (CMP-0.8) purified CMP to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish (mean initial weight 2.9 g) for 56 days. In general dietary CMP supplementations tended to improve growth performances (final body weight, % weight gain and specific growth rate), in which significantly highest performances were found in diet group CMP-0.4 followed by diet groups CMP-0.8 and CMP-0.2. CMP supplementation resulting in increased feed conversion efficiency and protein efficiency ratio and highest value (P < 0.05) obtained in diet group CMP-0.8. Diet groups with CMP supplementation ≤ 0.1% (Control, CMP-0.1) showed significantly lowest growth and feed utilization performances. The capabilities enhancing immune functions of fish fed CMP supplemented diets were detected by non-specific and acquired immune parameters measured in this study. Fish fed diet group CMP-0.4 had the significantly higher total serum protein (TSP) than fish fed the control diet. Lysozyme activity (LA), peroxidase activity (PA) also showed increasing trend with the supplementation of CMP and it was numerically higher in diet group CMP-0.4. In contrast, catalase activity (CAT) decreased (P > 0.05) with dietary CMP supplementations. Dietary supplementation of CMP had an increase (P > 0.05) adaptive humoral immune responses (antibody titer) after 21 days of vaccination of formalin killed Vibrio anguillarum. In terms of oxidative stress diet groups CMP-0.2 and CMP-0.4 showed best condition with low oxidative stress and high antioxidant levels. Moreover, the fish fed CMP supplemented diets had better improvement (P < 0.05) in body ash contents, glucose and total cholesterol levels than the control group. The quadratic regression analysis of weight gain and TSP revealed that the optimal levels of dietary CMP supplementation ranged between 0.48 and 0.50% for juvenile red sea bream, which is also in line with the most of the growth and health performance parameters of fish under present experimental condition.