EFFECT OF AIRBORNE DUST ON HEALTH AND PERFORMANCE OF GROWING PIGS

The effect of high concentrations of airborne dust on the health and p erformance of growing pigs (55-82 kg) was determined by introducing me chanically ground fecal dust into the air space of the pigs in the fir st trial and feed dust in the second trial. Mean respirable dust level s during the light hours in the rooms injected with feed and fecal dus t were 111 and 56 particles/mL, respectively, while the mean level in the control rooms was 25 and 17 particles/mL, respectively. Lungs from 115 animals were collected during slaughter. No relationship was foun d between dust concentration and lung score or between dust concentrat ion and average daily gain. For the fecal and the feed dust trials, 38 % and 23% of the pigs had pneumonic involvement in over 10% of the lun g. The average daily gain was not significantly different between trea tments (mean 0.78 kg/d) and it was not affected significantly by the p ercentage of pneumonic involvement. A large amount of energy was requi red to reduce feed to the respirable range relative to that required f or fecal dust suggesting that most of the respirable dust is of fecal origin.