Effects of Aerial Ammonia on Growth and Health of Young Pigs1

The effects of graded concentrations of aerial ammonia on the performance of young pigs were studied. In each of three trials, four 4-week-old pigs from each of two litters were assigned to one of four air pollution exposure chambers. After 1 week, each chamber was randomly assigned to one of four atmospheres: filtered room air plus 0 (control), 50, 100 or 150 ppm of aerial ammonia. Pigs averaged 8.4 ± .26 kg body weight at the start of the treatment period. They were continuously exposed to these air regimens for 4 weeks. Individual body weights and feed disappearance within chambers were measured weekly. Following the exposure period, pigs were killed and examined grossly and histopathologically. Regression models were fitted to growth and gain to feed (G:F) data. The growth model indicated that aerial ammonia decreased pig growth. Percentage reductions from controls in average daily gain were 12, 30 and 29% for 50-, 100- and 150-ppm exposed groups, respectively. G:F values derived from the regression model were .53, .58, .58 and .53 for the respective groups. Pigs exposed to 50 or 100 ppm aerial ammonia appeared to be more efficient converters of feed to body weight gain than were controls or 150-ppm exposed pigs. An acute inflammatory reaction was observed in the tracheal epithelium of pigs exposed to aerial ammonia at 100 or 150 ppm, but not in controls or those subjected to 50 ppm. A mild-to-heavy acute exudate in the turbinate lumen was observed in some pigs exposed to 100 or 150 ppm ammonia.