Thus, according to one aspect, the present application provides a method for the preparation of an immunogenic composition for the treatment and/or prophylaxis of mycoplasma infections in a subject comprising a) cultivation of mycoplasma bacteria in a serum-reduced or swine serum free, eukaryotic cell system; b) obtaining an antigen of the mycoplasma bacteria; and c) addition of a pharmaceutically acceptable carrier, wherein the mycoplasma antigen is a whole inactivated bacterin. According to a further aspect, all of the mycoplasma antigens within the immunogenic composition are whole inactivated bacterins. The inactivated mycoplasma antigens can be obtained in such that step b) of the method described hereinabove includes an inactivation step. Thus, according to a further aspect, method is provided for the preparation of an immunogenic composition for the treatment and/or prophylaxis of mycoplasma infections in a subject comprising a) cultivation of mycoplasma bacteria in a serum-reduced or swine serum free, eukaryotic cell system; b) obtaining an antigen of the mycoplasma bacteria and inactivating the mycoplasma antigens; and c) addition of a pharmaceutically acceptable carrier.