Dietary Administration of Engineered Nano-selenium and Vitamin C Ameliorates Immune Response, Nutritional Physiology, Oxidative Stress, and Resistance Against Aeromonas hydrophila in Nile Tilapia (Oreochromis niloticus)

Functional trace elements and vitamins can boost immunity and anti-oxidative response in aquatic animals with effects on nutritional physiology. Nano-selenium (nano-Se) and vitamin C (VC) have been used as immunomodulators and antioxidants in fish feed. The present work was performed to determine the protective effects of diets supplemented with different combinations of nano-Se and VC on Nile tilapia (Oreochromis niloticus). Triplicate groups of 20 fish/tank (13.87 +/- 0.10 g) were reared and fed with basal diet (control-T1) (without supplementation of nano-Se and VC) and three experimental diets as T2, T3, and T4 (100, 200, and 300 mg/kg VC respectively) with a pre-determined dose of nano-Se (1.0 mg/kg) for 90 days. Different immune indices, haemato-biochemical, and antioxidant activities were measured at the end of the first, second, and third months of feeding. The findings depicted that significantly (p < 0.05) higher growth was observed in T4. Red blood cells, white blood cells, and haemoglobin were found significantly (p < 0.05) higher in T4 for the third month. Serum biochemical-immunological indices (alkaline phosphatase, glucose, cholesterol, lysozyme, myeloperoxidase, total protein, albumin and globulin) followed the same trend. Furthermore, antioxidant assays such as catalase, superoxide dismutase, glutathione peroxidase, glutathione S-transferase, and malondialdehyde were significantly (p < 0.05) improved in T4 for the third month. Significantly (p < 0.05) least cumulative mortality against Aeromonas hydrophila was obtained in the fish-fed diets incorporated with nano-Se and VC. Therefore, dietary supplementation with nano-Se and VC is noteworthy for improving growth, serum biochemical status, immune response, antioxidant status, and disease resistance.