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Relative and Qualitative Aspects of Aerial Bacteria and Dust in Swine Houses

University of Illinois at Urbana-Champaign, Urbana 61801

¹ Animal Science Department. Address reprint requests to: 124 Animal Sciences Laboratory, Urbana, Illinois 61801.

Abstract

Aerial levels of bacterial-colony-forming particles (BCFP) in lung-depositable size ranges were determined using an eight-stage Andersen viable sampler with tryptose agar. Aerial levels of BCFP4.7 µm and 3.3 µm in aerodynamic diameter were significantly and positively correlated with total-aerial-BCFP level in swine-house air. On average, 31% of aerial BCFP were 4.7 µm and 15% were 3.3 µm in four University enclosed swine houses (n = 192); 30% and 22%, respectively, in a University modified-open-front house (n = 44) and 28% and 11%, respectively, in 12 houses at five commercial operations (n = 24). Aerial-dust level was determined using a Staplex high-volume sampler. Aerial-BCFP and -dust levels were significantly and positively correlated. There tended to be fewer aerial BCFP per unit of aerial dust in the modified-open-front house than in the enclosed houses at the University.

Ten swine houses at commercial operations and four at the University were studied a total of 16 times to determine concentrations and sizes of aerial bacterial particles which formed colonies on tryptose (general medium), Chapman-Stone (special medium for staphylococci), KF Streptococcus (fecal streptococci) and MacConkey (coliforms) agars, respectively. Ratio of bacterial-colony-forming-particle (BCFP) count on Chapman-Stone agar to that on tryptose averaged .36, that on KF Streptococcus to that on tryptose averaged .13 and that on MacConkey to that on tryptose averaged less than .01. Twenty-one percent of the staphylococcal BCFP and streptococcal BCFP, respectively, and 9% of the coliform BCFP, were lung-depositable (4.7 µm in diameter). Nitrogen content of aerial dust in a swine-finishing house, in which a 13% crude-protein (CP) diet was fed, averaged 4.6%, or (4.6 x 6.25) = 28.7% CP (n = 17). Settled dust in a farrowing house, in which a 12% CP diet was used, averaged 23.3% CP (n = 6), whereas that in a room in which diets having 12 to 16% CP were prepared averaged 13.0% CP (n = 4). It was concluded that much of the dust in swine-house air was feed dust.

² Now Agronomy Department, formerly Animal Science Department.

³ Now The Agricultural Institute, Moorepark, Fermoy, Ireland, formerly Animal Science Department, UIUC.

⁴ Advice on statistical analyses by H. W. Norton and technical assistance by Vickie J. Meares are gratefully acknowledged.