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Fish Shellfish Immunol. 2019 Jun;89:672-676. doi: 10.1016/j.fsi.2019.04.037. Epub 2019 Apr 13.

Dietary supplementation of olive leaf extract increases haematological, serum biochemical parameters and immune related genes expression level in common carp (Cyprinus carpio) juveniles.

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Bartın University, Faculty of Science, Department of Molecular Biology and Genetics, Bartın, Turkey.
Department of Forestry, Bayramiç Vocational School, Çanakkale Onsekiz Mart University, Çanakkale, Turkey. Electronic address:
Department of Aquaculture, Faculty of Marine Science and Technology, Çanakkale Onsekiz Mart University, Çanakkale, Turkey.


The present study investigated the effects of dietary olive leaf (Olea europea L.) extract (OLE) on some blood parameters and immune (TNF-α, IL-1ß and IL-8) related genes in different tissues (head kidney, liver and spleen) and resistance of common carp, Cyprinus carpio to Edwardsiella tarda. Five diets were prepared for fed fish (mean body weight 15.90 ± 0.93 g) with different rates of OLE (0.0%, 0.1%, 0.25%, 0.50% and 1.0%). A control diet was prepared non-supplemented with OLE. Increased haematocrit ratio, serum myeloperoxidase activity, immune response gene levels (IL-1β in head kidney tissue and TNF-α in spleen tissue) and survival rate against E. tarda particularly in the 0.1% OLE treatment group. In conclusion, results of the present study show that feeding common carp with a diet containing 1 g/kg OLE over a period of 60 days might be adequate to improve fish immune parameters, and survival rate against E. tarda. Therefore, OLE can be used as a dietary additive to prevent E. tarda in common carp.


Blood parameter; Common carp; Gene expression; Olive leaf extract

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