Abstract: In recent years, the prevalence of an infectious disease characterized by high morbidity and mortality in sheep herds has been observed in Xilin Gol League of Inner Mongolia. This disease was finally diagnosed as eperythrozoonosis, a zoonosis caused by Mycoplasma ovis （M. ovis）. In order to lay a foundation for the in-depth study on M. ovis, the optimum conditions for in vitro culture of M. ovis was determined, with emphasis on formula improvement of culture medium by referring the Mycoplasma culture medium. The best growth of M. ovis was observed in a self-prepared ZP-S-BS culture medium under 37 ℃ with replacement of half fresh medium at 48 h. The erythrocytes infected with M. ovis could be long-term in vitro cultured with the ZP-S-BS culture medium. The eluted M. ovis was able to be continuously cultured in vitro up to 260 days in ZP-S-BS culture medium and propagate slowly.

Key words: Mycoplasma ovis, in vitro culture, optimum culture conditions