effects of multispecies probiotic combination on growth performance, biochemical indices, and non-specific immune responses in common carp (<i>cyprinus carpio</i>)

Background: probiotic bacteria as an alternative to antibiotics are necessary for aquaculture due to the prevalence of recurrent diseases. objectives: this study investigated the effect of a probiotic combination, including endogenous bacteria such as lactobacillus plantarum, lactobacillus bulgaricus, lactobacillus acidophilus, and lactobacillus rhamnosus, on the health status of common carp. methods: the probiotic combination was added to carp basal diets in three treatments, 1 to 3, each containing 106 cfu g -1, 10 7cfu g -1, and 10 8cfu g -1probiotic combination, respectively. a fourth group (group 4) was used as a control and received no probiotic treatment for six months. after 3 months, the fish’s growth performance, biochemical indices, and innate immune responses were evaluated. results: the growth indices, such as the daily growth rate, specific growth rate, condition conversion factor, condition factor, and protein efficiency, significantly improved in treatments 2 and 3 compared to the other groups (p < 0.05). investigation of complement, lysozyme, and serum bactericidal activity showed that probiotic treatments positively affected the immune system of common carp, with treatments 2 and 3 demonstrating a greater effect (p < 0.05). biochemical factors were also investigated, showing decreased cholesterol and triglyceride levels in the probiotic treatment group. moreover, the probiotic treatments resulted in a significant reduction in the activity of liver enzymes ast and alp compared to the control group (p < 0.05). conclusions: a probiotic combination with concentrations of 5 × 10 7cfu g -1and 5 × 10 8cfu g -1of food can positively impact common carp’s growth performance, immune system, and biochemical parameters. as no significant difference was seen between the two concentrations, the lower one is recommended.