[Efficacy of spiramycin and tylosin in preventing mycoplasmosis in chicks experimentally infected with mycoplasma gallisepticum].

In order to evaluate the activity of two drugs (spiramycin and tylosin), one-day-old chicks are inoculated with a virulent strain of Mycoplasma gallisepticum (MG) and given spiramycin (3 different doses) or tylosin (1 dose) for two or three days. Effectiveness is assessed on different criteria: mortality, symptoms, weight gains, gross lesions, MG tracheal recovery and serology. Results show that spiramycin and tylosin have the potential of reducing mortality, symptoms and lesions. Weight gains of treated birds are greater than those of infected untreated birds. However, MG was recovered from tracheas of all treated birds.