Enhanced mucosal immune responses, immune related genes and growth performance in common carp (Cyprinus carpio) juveniles fed dietary Pediococcus acidilactici MA18/5M and raffinose.

The present study was conducted to evaluate the effects of dietary Pediococcus acidilactici (PA) and raffinose (RF) alone or in combination on growth performance, mucosal immune factors and immune related genes expression in common carp (Cyprinus carpio) juveniles. Fish with initial weight of 10.0 ± 2.5 g were fed the following experimental diets for 60 days: control (without supplementation), prebiotic (2 g RF kg^-1 diet), probiotic (6 × 10⁸ CFU g^-1PA) and synbiotic (2 g RF kg^-1+ 6 × 10⁸ CFU g^-1PA). Carp fed synbiotic and probiotic diets had the highest (19.53 ± 0.16) and the lowest (18.05 ± 0.65) final body weight, respectively and the other experimental groups showed intermediate values. Singular administration of PA or in combination with 2 g RF kg^-1 significantly increased skin mucus total immunoglobulin (Ig) and protein compared other groups, meanwhile, values of skin mucus protease activity enhanced by dietary immunostimulants administration in comparison with the control (P < 0.05). The expression of gene encoding lysozyme in skin pronouncedly increased by supplementing diets with singular or mixture of PA and RF; however, the expression of intestinal lysozyme gene as well as tumor necrosis factor-α genes expression in skin and intestine were not affected by administrating different immunostimulants (P > 0.05). The highest growth performance was noticed in fish fed synbiotic (P < 0.05). Overall, the combination of 2 g RF kg^-1 with 6 × 10⁸ CFU g^-1PA is recommended for improving immunological responses of C. carpio juveniles.