Immunostimulatory Potency Developed in Pangasianodon hypopthalmus Against Aeromonas hydrophile Through Ocimum sanctum Supplemented Diet

The culture of Pangasianodon hypopthalmus has gained considerable popularity. However, it suffers from haemorrhagic septicaemia and epizootic ulcerative syndrome due to Aeromonas hydrophila, a causative bacterial agent having antibiotic resistance. The effect of Ocimum sanctum leaf extract was evaluated against A. hydrophila infections in P. hypopthalmus in the present study. Four groups of fishes were fed on the formulated diets containing O. sanctum extract at 0 (T₀), 1 (Tj), 2 (T₂) and 4 (T₃) per cent levels for 60 d. Fishes were challenged with A. hydrophila at 45 d post-feeding and, the relative percentage survival (RPS) was recorded over the 15 d post-challenge period. The aqueous extract of O. sanctum contained 7.5 mg GAE/mL of total phenolic compounds and 6.42 mg QE/mL of total flavonoids. The highest RPS was found in T₂ (36%), followed by T, (27%) and T₃ (9%). Blood samples were collected for analyses of haematological, immunological and biochemical parameters on 15, 30, 45 and 60 d and growth performance evaluated at the end of 45 d. Results revealed that O. sanctum supplemented diet significantly (P<0.05) enhanced respiratory burst activity, serum lysozyme activity in T₂, total serum protein, globulin, total erythrocyte counts, total leucocyte counts and haemoglobin in J\. Growth performance in terms of weight gain, SGR and FCR were improved in T_; and T₂, compared to T₃ and control. In conclusion, dietary Ocimum sanctum extract in the range of 1–2% showed significantly (P<0.05) higher RPS against A. hydrophila infection compared to die control.