Evaluation of probiotic adequacy, immunomodulatory effects and dosage application of Bacillus coagulans in formulated feeds for Catla catla (Hamilton 1822)

The present study was conducted to study the probiotic properties, antagonistic effect against pathogenicAeromonas hydrophilaof Bacillus coagulansisolated from intestine of healthyCatla catlaHamilton, 1822; and its optimum dosage for growth promotion and immunostimulation. The isolated B. coagulansfrom the gastrointestinal tract of C. catlawas first assessed for its probiotic properties viz., antagonism towards pathogen and cell surface adhesion. A feeding trial of 90 days was conducted to optimize the inclusion level ofB. coagulansin diets andC.catlafingerlings (avg. wt. 0.30±0.03g) were fed on feed supplemented with 1x103(diet D1), 2x103(diet D2), 3x103(diet D3)and 5x103(diet D4)B. coagulansCFU g-1of feed in triplicate treatments. The growth and digestibility parameters, intestinal enzyme activities were significantly higher in group of fish fed on feedD3 (3x103CFU g-1) in comparison to other dietary treatments except for food conversion ratio which was significantly higher in control group. Significantly higher value of carcass protein level, lower excretion of metabolites (ammonia and phosphates), enhancement of non-specific immune response and increase of total Erythrocyte count (TEC) and total Leucocyte Count (TLC) were observed in fish fed with probiotics supplemented diets. The results obtained in the present study support the use of B.coagulansfor better growth and proper nutrient utilization. The broken line analysis wascarried out and polynomial fit curve further suggest that the optimum concentrations of B. coagulans as high as 3000 (3x103) CFU g-1of feed is required for improving the overall physiological performance and enhancement of defense mechanisms in the fingerlings of C.catla.