Airsacculitis in Broilers from Mycoplasma synoviae: Effect on Air-Sac Lesions of Vaccinating with Infectious Bronchitis and Newcastle Virus

Abstract

SUMMARY Broilers vaccinated against infectious bronchitis and Newcastle disease developed airsacculitis following aerosol exposure to broth cultures of Mycoplasma synoviae. Incidence and severity of lesions was maximum 3 weeks postexposure, but few lesions were grossly visible 6 weeks postexposure. In another trial, aerosol exposure of unvaccinated birds or bronchitis vaccination 5 days after mycoplasma exposure resulted in a low incidence of airsacculitis with mild lesions. Vaccination 5 days prior to mycoplasma exposure led to increased severity of airsacculitis, while vaccination and mycoplasma exposure on the same day resulted in the highest incidence and severity of lesions. Aerosol exposure to M. synoviae in broilers vaccinated simultaneously against both infectious bronchitis and Newcastle disease led to depressed growth and less efficient feed conversion.