Immunostimulatory Effect of Phoenix Dactylifera Supplemented Diet on Aeromonas hydrophila Infected Clarias gariepinus

Abstract

Background: Phoenix dactylifera fruit has been widely reported for its effective anti-inflammatory properties. Therefore, the effect of P. dactylifera on immune responses was evaluated in Aeromonas hydrophila infected Clarias gariepinus. Methods: P. dactylifera fruit powder was used as feed inclusion at 0 (control), 0.5, 1.0 and 2.0% concentrations to the pelleted fish diet of C. gariepinus juveniles. A total of 75 fish were divided into fourgroups (n=15) . The fish were fed with the formulated feed twice a day (08:00 h and 17:00 h), and terminated 24 h before the commencement of the microbial inoculation with inactivated Aeromonas hydrophila bacteria. The fish were later challenged with active Aeromonas hydrophila after seven weeks of experimental feeding. Blood samples were collected from fish while haemagglutination and phagocytic assays were used to determine the antibody titres and phagocytic action of the immune cells, respectively. Then, the micronucleus assay was used to determine the chromosomal damage effect of Aeromonas hydrophila pathogen on exposed C. gariepinus. Results: After the challenge, the groups fed with 0.5 and 2.0% date showed significantly (p˂0.05)elevated level of immune responses with antibody titres of 231.49±77.06 and 257.18±51.37, and phagocytic activity values of 0.07±0.01 and 0.04±0.00, respectively. The clastogenic effect of A. hydrophilaon the peripheral blood of infected C. gariepinus was observed, this was significantly reduced in 2% P. dactylifera fed group. Also, increase white blood cell count was observed in the C. gariepinus group fed with 0.5% date supplement. A higher lymphoid organ index was also observed in fish fed with the supplemented diet, as compared to the control. Conclusions: These results indicate that P. dactylifera fruit powder enriched diet showed an immune-boosting and reduction of the DNA damaging effect in bacteria-infected C. gariepinus