Immunomodulation, Fish Health and Resistance to Staphylococcus aureus of Nile Tilapia ( Oreochromis niloticus ) Fed Diet Supplemented with Zinc Oxide Nanoparticles and Zinc Acetate

Recently some metal-based nanoparticles have gained serious attention from aquaculture and the fish feed industry as feed supplements. Oral supplementation of zinc oxide nanoparticles (ZnO-NPs) in fish feed, replacing Zn acetate (conventionally used zinc), is suggested as a cost-effective and efficient approach. Our study assessed the response of Nile tilapia, Oreochromis niloticus , fingerlings after its diet supplemented with chemically synthesized ZnO-NPs and zinc acetate under controlled conditions. ZnO-NPs were chemically synthesized and characterized. Tilapia fingerlings with an average body weight of 09.12 ± 1.23 g were randomly distributed into five groups. An 8-week trial was set with control and four experimental groups. Basal diet (D1) was used as control, whereas D2, D3 and D4 comprising 20, 40, and 60 mgkg −1 ZnO-NPs supplementation were experimental diets. Additionally, D5 was composed of a basal diet supplemented with 40 mgkg −1 of conventionally used zinc acetate. Significant improvement ( P < 0.05) was found in nanoparticles and Zn acetate supplemented groups as compared to control, while the 40 mgkg −1 Zn-NPs supplemented diet (D3) showed best performance in terms of health parameters, oxidative status and disease resistance. Antioxidant profiling was based on catalase, superoxide dismutase, glutathione’s transferase, and malondialdehyde; hematology included Hb, WBCs, RBCs, HCT MCV, MCH and MCHC; immunological parameters comprised IgM, lysozyme activity, phagocytic activity, respiratory burst activity, cholesterol, aspartate aminotransferase, alanine aminotransferase, glucose content, and total serum proteins. We report that the D3 (40 mgkg −1 ZnO-NPs supplementation) significantly ( P < 0.05) improved health-related parameters as compared to the other groups. Moreover, D3 also showed significantly decreased mortality percentage when challenged by Staphylococcus aureus , while the Zn acetate supplemented diet group showed better results as compared to control. Overall results suggest the basal diet supplemented with 40 mgkg −1 ZnO-NP for enhanced health parameters, oxidative status, immune response, and disease resistance. Hence, 40mgkg −1 ZnO-NP can be recommended to formulate the practical diet of fish to boost health improvement, immunomodulation, and resistance to bacterial disease.