The effects of combined or singular administration of formic acid and Pediococcus acidilactici on stress resistance, growth performance, immune responses and related genes expression in common carp, Cyprinus carpio

Abstract

In the current study, the effects of dietary formic acid and probiotic supplementation in growth, serum immune parameters, salinity tolerance, and gene expression of common carp, Cyprinus carpio were studied. 360 healthy common carp with average weight of (5.54 ± 1.08 g) were randomly stocked into 12 fiberglass tanks with 300 L capacity having 30 individuals in each tank. The fish were fed for 56 days with four experimental diets i.e., Control (Formic acid 0 + Pediococcus acidilactici 0), FA (Formic acid 0.3% + Probiotic 0), Pro (Formic acid 0 + P. acidilactici 0.1%), and FA+Pro (Formic acid 0.3% + P. acidilactici 0.1%). Growth performance, serum immune parameters, and gene expression of the experimental fish were examined at the completion of the feeding study. Fish fed the combination of formic acid and probiotic (FA+Pro) caused significantly (P < 0.05) higher weight gain and lower feed conversion ratio compared to the control and the experimental diets. Specific growth rate didn’t show significant differences among experimental diets (P > 0.05). Fish administered formic acid and probiotics (FA+Pro) also had significantly higher serum immune parameters (total protein, globulin, and lysozyme) than the control (P < 0.05). Moreover, the relative expression of GH, IGF1, Lyz, and IL-1 genes increased significantly (P < 0.05) with combined supplementation when compared to fish fed just formic acid or probiotics and the control. During 7 days of exposure to saline conditions, fish fed with a combination of formic acid and/or probiotic showed a significantly higher survival rate (P < 0.05). It can be concluded that combined administration of P. acidilactici as probiotic with an organic acid (FA) exert much more beneficial effects rather than singular administration. Therefore, it can be considered as promising feed additive for carp culture.