Evaluation of Immunomodulatory Effect of Dietary Probiotics on the Common Carp, Cyprinus carpio

Fish culture is increasing to compensate the shortage of animal protein all over the world. Fish under intensive culture conditions will be badly affected and often fall prey to different microbial pathogens that have been treated with chemotherapeutic substances of which antibiotics were intensively used. The use of natural immunostimulants in fish culture for the prevention of diseases is a promising new development and could solve the problems of massive antibiotic use. Evaluation of immunomodulatory effect of the dietary probiotics on the common carp, Cyprinus carpio L. has been studied for the period of one month and the experiments such as, mortality, phagocytic activity and growth rate are conducted through this present study. To prepare the probiotic enriched diet, the colony forming units were found. For Lactobacillus acidophilus, the colony forming units were found to be 4.6x107 CFU mL-1 for 105 and 2.1x109 CFU mL-1 for 107 concentrations. The Bacillus subtilis were found to be 3.47x107 CFU mL-1 for 105 concentrations and 1.64x109 CFU mL-1 for 107 concentrations. Then these bacterial suspensions of 5 mL were sprayed into the 50 g of feed (100 mL kg-1 diet) with constant mixing. The experimental group III fed with 105 cells of Bacillus subtilis showed minimum mortality rate and maximum mean leucocyte count and growth rate on all days when compared to other experimental groups.