Diurnal and Annual Fluctuations of Aerial Bacterial and Dust Levels in Enclosed Swine Houses

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Abstract
Concentration of bacterial-colony-forming particles (BCFP) in the air of enclosed swine houses was observed continuously over a 24-hr period with an Andersen continuous monitor. Sampling was done for four 24-hr periods in a swine nursery and a swine growing house. In each period, aerial BCFP/m3 of air were measured for each half-hourly interval. Aerial BCFP concentration within each 24-hr period was roughly a sinusoidal function of time, but runs within a house were asynchronous. No one time during a 24-hr period could be recognized as preferable for monitoring in studies of long-term changes in aerial BCFP concentration. Aerial levels of BCFP and dust were determined 44 or 48 times over 15 months in each of four enclosed and one modified-open-front University swine gestation and farrowing houses typical of those now used in north-central United States. An Andersen viable sampler and tryptose agar were used to measure BCFP, and a Staplex high-volume air sampler to measure dust. Common logarithms of aerial BCFP levels (no./m3) for the five houses (mean ± SE) were: 5.16 ± .06, 4.88 ± .05, 5.02 ± .06, 4.99 ± .08 and 4.33 ± .06. These levels were comparable to those observed in 12 swine houses at five commercial swine operations. Common logarithms of dust levels (µg/m3 were: 3.08 ± .05, 3.03 ± .06, 3.35 ± .05, 3.03 ± .06 and 2.89 ± .08, respectively. These levels were generally lower than those observed in 11 houses at five commercial operations. Both aerial BCFP level and aerial dust level were significantly and negatively correlated with median outside temperature. Regression analyses indicated that common logarithm of aerial BCFP level increased around .02 per Celsius-degree decrease in median outside temperature for the day and that common logarithm of aerial dust level increased around .01 per degree decrease. Copyright © 1975. American Society of Animal Science . Copyright 1975 by American Society of Animal Science.

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