Abstract:The immunomodulatory activity of cattle bone peptide （CBP）was investigated based on RAW264.7 macrophages and immunosuppressed mice induced by hydrocortisone.At the cellular level，the effects of different concentrations of CBP on the proliferation and phagocytosis of RAW264.7 cells were investigated.The nonspecific immune activity of CBP was investigated by weight change，immune organ index，peripheral blood white blood cell count，and the phagocytosis ability of monocytes macrophages.Delayed-type hypersensitivity and serum hemolysin levels were used to determine the specific immune activity of CBP.The results of in vitro cell experiments showed that CBP enhanced the proliferation and the phagocytic capability to neutral red of RAW264.7 cells.Compared to the immunosuppressed control group，most indexes of the mice treated with CBP improved to varying degrees，including the body weight，relative spleen index，relative thymus index，relative white blood cell number，carbon clearance ability，phagocytic ability of fluorescent microspheres，and serum hemolysin levels.Moreover，the immunomodulatory activity and dosage of CBP were positively correlated.The results show that CBP can enhance the body’s non-specific and specific immune activity，thereby providing a theoretical basis for further application of CBP in the field of food and medicine.