Effects of dietary levels of essential oil extracts from Moringa oleifera and Artemisia afra on kidney histology,haemato‐immunological parameters and disease resistance in Clarias gariepinus

This experiment investigated the effect of dietary supplementation with essential oils from Artemisia afra and Moringa oleifera on haemato‐immunological parameters and resistance in Clarias gariepinus (African Sharptooth catfish) (Burchell, 1822) challenged with Aeromonas hydrophila. The experiment lasted for 45 days. Prior to and postchallenge, white blood cells significantly increased (p < .05) from the 3% to 12% M. oleifera and A. afra supplementation. Pre‐challenge, no significant differences (p > .05) in red blood cells, haemoglobin and haematocrit were observed between the control and M. oleifera supplementation, while in the A. afra supplementation, RBC and HCT significantly increased from the 6% to 12%. Postchallenge, RBC, HGB and HCT were significantly lower (p < .05) in the control and the 3% and 6% M. oleifera and A. afra supplementation. Both pre‐ and postchallenge, nitro‐blue tetrazolium levels significantly increased (p < .05) from the 3% to 12% M. oleifera supplementation while no significant differences (p > .05) were observed in lysozyme activity between the control and treatment groups. In A. afra, NBT and lysozyme activities increased significantly (p < .05) from the 6% to 12% supplementation pre‐ and postchallenge. Survival rate increased from the 3% to 12% in M. oleifera and A. afra supplementation groups. Significant kidney histological alterations were noted in the control and the 3% and 6% supplementation of both plants postchallenge, while no major histological changes were observed between treatment groups and the control pre‐challenge. The results demonstrate that EO from M. oleifera and A. afra can improve immunity and enhance survival in C. gariepinus.