Dietary apple peel-derived pectin improved growth performance, antioxidant enzymes and immune response in common carp, Cyprinus carpio (Linnaeus, 1758)

The trial conducted to investigate the effects of apple peel-derived pectin (APDP) on the growth, antioxidant enzyme activity and immune parameters in blood of common carp (Cyprinus carpio, 19.94 ± 0.03 g). Four dietary treatments with 0 (control), 0.5, 1 and 2% APDP were tested in an eight-week trial. Obtained data allowed assessing the growth, feed efficiency and immunological parameters as lysozyme, catalase activity (CAT) and superoxide dismutase (SOD). Fish fed APDP treatments showed improvements in growth parameters and feed conversion ratio (P < 0.05). The dietary pectin inclusions significantly (P < 0.05) increased the skin mucus immunological parameters; including serum total immuno globulin (STlg), and lysozyme activity. Regarding serum antioxidant defense, carp fed diets supplemented with APDP showed higher (P < 0.05) CAT and SOD activity levels versus control group. Although the supplementary diets did not differ significantly. The serum and skin mucus anti-bacterial activity tests against ten different bacterial strains demonstrated that dietary pectin significantly affected anti-bacterial activity, suggesting that the dietary administration of APDP favorably affects growth and immune responses. © 2020 Elsevier B.V.