Ginger powder modulates key immune and antioxidant pathways in Nile tilapia, conferring protection against Aeromonas veronii infection.

This study evaluated the efficacy of dietary ginger powder (GP) at 1% in enhancing immunity and resilience against bacterial infection in Nile tilapia (Oreochromis niloticus). Fish were grouped into control and GP-supplemented groups, with the latter fed a GP-enriched diet for 14 days before a challenge with Aeromonas veronii, with continued feeding on the same diet for 7 days post-challenge. Results indicated that GP supplementation significantly enhanced red blood cell (RBC) count, hemoglobin (Hb), packed cell volume (PCV), total protein (TP), and globulin levels, while reducing alkaline phosphatase (ALP) activity, albumin-to-globulin (A/G) ratio, and malondialdehyde (MDA) concentration, without inducing pathological alterations in the liver or spleen. In contrast, the A. veronii-challenged group exhibited reduced RBCs, Hb, and PCV%, along with increased leucocytic count and liver enzyme activities. This group also exhibited elevated immune and oxidative stress markers, including respiratory burst activity (RBA), nitric oxide (NO), hydrogen peroxide (H2O2), MDA, and superoxide dismutase (SOD), while demonstrating reduced activities of glutathione peroxidase (GPx) and catalase (CAT). Additionally, the challenged group showed suppressed interleukin-1β (il-1β) and hepcidin, the key iron regulatory hormone encoded by hepcidin antimicrobial peptide (hamp), gene expression (P < 0.05), with marked histopathological alterations in the liver and spleen. Notably, GP supplementation mitigated many of these adverse effects, improving hematological and biochemical profiles, reducing oxidative stress, enhancing immune-related endpoints, and decreasing histopathological damage. Overall, the findings clearly demonstrate that GP supplementation could serve as a promising functional feed additive, improving fish health and boosting resilience against bacterial infections.