Dietary intake of bamboo vinegar and charcoal powder(BVC)enhances resistance of African catfi sh Clarias gariepinus to bacterial pathogen

摘要

Although the immunomodulatory activity of bamboo vinegar and charcoal powder(BVC)has been increasingly documented in domestic animals,the use of BVC as immunostimulant in fi sh aquaculture awaits verifi cation.In the present study,the immunostimulatory impacts of dietary BVC intake were investigated in an important aquaculture fi sh species,the African catfi sh Clarias gariepinus.Results show that the pathogen resistance of African catfi sh was signifi cantly improved by dietary BVC intake at the tested levels(0.5%-2%),as indicated by higher survival rates(approximately 1.52-1.85 times that without BVC supplementation)upon intraperitoneally injection of bacterial pathogen Aeromonas hydrophila.In addition,both the count and phagocytic activity of blood cells were signifi cantly up-regulated by a 45-day dietary supplementation of BVC.Moreover,compared to that of the control,fi sh individuals fed BVC containing diets exhibited signifi cant higher activities of superoxide dismutase(SOD),myeloperoxidase(MPO),and lysozyme(LYZ).The content of immunoglobulin M(IgM)in serum of African catfi sh was also induced by dietary BVC supplementation.Furthermore,the expression levels of interleukin-8(IL-8),toll-like receptor 1 and 5(TLR1 and TLR5),myeloid diff erentiation factor 88(MyD88),and nuclear factor kappa B(NFκB)in the head kidney were signifi cantly up-regulated.Our fi ndings indicate BVC could be an eff ective immunostimulant in teleost species,which may enhance fi sh immunity through improving hematic parameters,activating bioactive humoral molecules,and up-regulating immune related molecular pathways.