Determination of Some Haematological Parameters and Disease Resistance Capacity to Aeromonas hydrophila Infection in the Nile tilapia, Oreochromis niloticus L. Fed Dietary Supplementation of Ginger (Zingiber Officinale)

Aquaculture is one of the fast-growing food industries in the world. However, this industry is hampered by diseases. The present study aimed to determine the effect of ginger powder on the haematology of the Nile tilapia, Oreochromis niloticus, and resistance to A. hydrophila infection. A completely randomized design was used for the experiment. A total of 300 healthy live experimental Nile tilapia individuals, with 20 ± 1.00g body weight and 11.06 ± 0.08cm body lengths, were randomly divided into five treatment glass aquariums. Each experiment was conducted in triplicates, representing four treatments (3, 5, 8 and 12 g ginger/kg diet) and one control (0.00 ginger/kg diet). After eight weeks of the feeding trial, 0.2ml of Aeromonas hydrophila culture containing 1.0 × 10⁷ CFU/ml (LD50) was given by intraperitoneal (IP) injection. Blood samples were collected before and after the bacterial infection of the fish for haematological analysis. The result showed that blood parameters of Oreochromis niolticus in all ginger concentrations were significantly higher compared to the control diet before infection (P< 0.05). Oriochromis niloticus fed a diet at a concentration of 5 g ginger/kg showed the highest red blood cell (RBC), haematocrit value, haemoglobin content, mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), white blood cell (WBC), lymphocytes and monocytes. Erythrocyte sedimentation rate (ESR), mean corpuscular volume (MCV), WBC, neutrophils and monocytes showed significant increment, while RBC, haemoglobin content, haematocrit value, MCH, MCHC, and lymphocytes decreased significantly after infection (P< 0.05). The results also revealed that the Oriochromis niloticus treated with 5, 8 and 12 g/kg of ginger showed a decrease in mortality rates, compared to the control diet after infection. The fish fed 5g/ kg of ginger had the highest survival rate (81.66%). In conclusion, 5 g/kg of ginger had positive effects on Oriochromis niloticus innate immunity system and prevented Aeromonas hydrophila infection. Therefore, the use of 5 g/kg dietary ginger powder in the diet of Oriochromis niloticus juvenile is recommended.