UTTAR PRADESH JOURNAL OF ZOOLOGY

The present investigation reports the first-ever studies on the immunostimulatory efficacy of Lawsonia inermis supplementation against Aeromonas hydrophila in Catla catla fingerlings with its influence on their growth performance, disease resistance, survival rate, cumulative mortality and innate immune response. Varied concentrations viz- 5 g/kg, 10 g/kg and 15 g/kg of L. inermis diet remarkably displayed an increased body weight, length, protein conversion ratio, specific growth and survival rate in a dose-dependent manner compared to negative control groups (C),  which were not challenged with A. hydrophila and administered the basal diet. In contrast, positive control groups (I) were challenged with the experimental bacteria and fed with basal diet. Cumulative mortality was significantly reduced across the experimental groups, suggesting an enhanced disease resistance in fish administered with L. inermis-enriched diet. The minimum cumulative mortality rate of 4.33 % in the negative control group followed by 7.67 % in the highest dose 15 g/kg (E-III), 15.67 %  in the mid-dose 10 g/kg (E-II) 36.33 % in the lowest dose, 5 g/kg  (E-I) and a maximum of 75.67% in the positive control (I) group were observed. It was also reported that during the 30-day post-challenge period, all experimental groups supplemented with the L. inermis diet revealed a concentration-dependent rise in innate immune response compared to the positive control and the negative control. Immunological studies like phagocytic, alternative complement, respiratory burst and lysozyme activities displayed the maximum values in the E-III, fed with 15 g/kg of L. inermis enriched diet, with a gradual decrease in  E-II and the least in E-I. Thus, an ideal dose of 15 g/kg of L. inermis as a herbal supplement is a possible nutritive immunostimulant in the fingerlings of C. catla against A. hydrophila.