Response of Swine to Atmospheric Ammonia and Organic Dust

SUMMARY Gaseous ammonia (NH3) and organic dust are 2 factors contributing to poor air quality in hog barns. Chronic coughing, lowered weight gains, and an increased incidence of enzootic pneumonia have been noticed in barns with high amounts of NH3 and dust. To evaluate the possible qualitative effects of these agents, pigs from 1 to 7 weeks of age were exposed in environmental chambers to 100 p.p.m. NH3, organic dusts, and combinations of NH3 and organic dust. Conjunctival irritation was evident for 1 week during the NH3 exposure and for 2 weeks during the NH3 and dust exposures. Changes were not detected in the appetites, mean daily gains, frequency of coughing, hemograms, or total serum lactic dehydrogenase activity. Histopathologic changes were limited to the nasal and tracheal epithelium. A 50 to 100% increase in the thickness of the tracheal epithelium with a concomitant decrease in the number of tracheal epithelial goblet cells was detected in pigs exposed for 2 to 6 weeks to 100 p.p.m. NH3. Similar lesions were detected in the nasal epithelium of pigs exposed to NH3 and organic dust. There was no evidence of structural damage in the bronchial epithelium or in the alveoli of exposed pigs.