This may be the main reason why the expression levels of IFN‐γ, IL‐2 and IL‐17 mRNA were reduced to different degrees when treated with QOL, and it was speculated that the anti‐coccidiosis effect of QOL might not be realized by regulating the expression levels of IFN‐γ, IL‐2 and IL‐17 mRNA. The gene discussed is IFNG; the disease is coccidiosis.