ABSTRACT
The dust of animal houses originates mainly from the feed (80–90%), the bedding material, the manure (2–8%),and the animals (2–12%) themselves. It consists substantically of organic matter. The factors determining the amount of dust in confinements include animal activity, temperature,relative humidity, ventilation rate, stocking density and volumetric air-space per animal, feeding method, and nature of the feed. This dust originating from various sources can carry gases, vapours and odours. The analysis of dust-borne trace gases is usually done by solvent extraction followed by gas chromatography. At least 60 compounds belonging to different chemical groupings were identified in the dust from animal houses. Volatile fatty acids and phenolic/indolic compounds were found to contribute mostly to the strong, typical odour of animal houses. Main components in these groups are acetic acid and p-cresol, respectively. In the dust from pig houses qualitatively and quantitatively nearly the same volatile fatty acids and phenols are found than in the air or in the slurry. One m3 of the exhaust air from a 500 head pig fattening unit can contain dust-borne 6.27 μg volatile fatty acids and 2.76 μg phenolic/indolic compounds. The concentration of odours on the dust particles seems to be much greater than in an equal volume of air. Filtering the dust from the exhaust air can reduce the odour emission from animal houses up to 65%. Another way to reduce the dust-borne odour emission is to avoid the release of dust in the animal house by wet feeding, vacuum cleaning or showering.
