Effects of atmospheric ammonia on young pigs experimentally infected with Bordetella bronchiseptica.

Effects of atmospheric ammonia on performance and respiratory tract health of young pigs experimentally infected with Bordetella bronchiseptica were studied. Treatments were: (1) control, (2) Bordetella inoculation (approx 10(9) bacteria/naris) alone, (3) Bordetella inoculation plus exposure to atmospheric ammonia at 34.7 mg/m3 (50 ppm), and (4) Bordetella inoculation plus exposure to atmospheric ammonia at 69.4 mg/m3 (100 ppm). Pigs weighted 8.01 kg (av) at start of treatment. Body weight and feed disappearance were measured weekly. After 4 weeks, all pigs were killed and examined grossly, and appropriate specimens were obtained for histopathologic examination. Regression models were fitted to growth, feed disappearance, and gain-to-feed data. The growth model indicated that Bordetella-inoculated pigs gained 26% less body weight than did controls, regardless of atmospheric ammonia concentration. Bordetella inoculation, regardless of ammonia exposure, reduced feed disappearance 12% below the control rate. Treatment difference was not noted in gain/feed data. Shrunken turbinates were observed in Bordetella-inoculated pigs. Shrinkage also appeared to be related directly to ammonia concentration. Rhinitis was confirmed histopathologically, and its severity was related with atmospheric ammonia concentration, but no difference was seen in the osseous core of the turbinates.