Can dietary jujube (Ziziphus jujuba Mill.) fruit extract alter cutaneous mucosal immunity, immune related genes expression in skin and growth performance of common carp (Cyprinus carpio)?

The present study investigates the effect of dietary Ziziphus jujube fruit extract [ZJFE] on skin mucus non-specific immune parameters as well as mRNA levels of immune related gene in the skin of common carp fingerlings. An eight-week feeding trial was performed using different levels of dietary ZJFE (0, 0.25, 0.5 and 1%). At the end of the trial skin mucus immune parameters (total Ig, lysozyme and protease activity), cytokines genes (il1b, il8, il10 and tnf-alpha) expression in skin and growth performance were studied. The result showed highest and lowest skin mucus total Ig were observed in fish fed diet containing 0.5% ZJFE and control group, respectively (P < 0.05). There were no significant difference among treatments regarding skin mucus lysozyme activity (P > 0.05). It should be noted that, feeding on 0.5 and 1% ZJFE significantly increased skin mucus protease activity (P < 0.05). Likewise, gene expression studies in skin showed significant increase of il1b expression in fish fed 0.5% ZJFE compared other treatments (P < 0.05). Also, il8 gene was noticeably up-regulated in 0.5 and 1% treatments compared to the control group (P < 0.05). While there were no significant difference between 0.25% JFE treatment and control in case of relative il10 gene expression (P > 0.05), feeding on diets containing 0.5% or 1% ZJFE significantly down-regulated il10 gene (P < 0.05). Our study indicated that relative expression of tnf-alpha gene significantly increased in treated groups (P < 0.05). Also, feeding on ZJFE supplemented diet improved growth performance parameters. Overall, this experiment demonstrated the potentially useful effects of ZJFE on skin mucosal immunity and performance of common carp fingerlings. © 2019 Elsevier Ltd