Influence of environment on airsacculitis: effects of relative humidity and air temperature on broilers infected with Mycoplasma synoviae and infectious bronchitis

Mycoplasma synoviae (MS) obtained from broiler chickens condemned for airsacculitis was used to determine the influence of air temperature and relative humidity on the severity of airsacculitis produced experimentally. Infectious bronchitis virus was administered to 3-week-old broilers 5 days before aerosol exposure to MS broth cultures, producing extensive airsacculitis within 21-day study periods. High (31-32 C), medium (19-24 C), and low (7-10 C) air temperatures were studied in conjection with high (75-90%), medium (38-56%), and low (23-26%) relative humidities. Airsacculitis was most extensive (45%) at low temperatures regradless of high or medium humidity. The incidence of airsacculitis was greater (39%) at low humidity than at high humidity (17%) when air temperatures were medium. At high temperature, the trend was toward more airsacculitis (12%) at high humidity than (5%) at low humidity. However, the effect of cold air temperature was more dominant than the effect of relative humidity.