[Total count of bacteria in the air of three different laying hen housing systems].

Bacteria in the air of animal housing is assumed to have an impact on the health of the humans and the animals in them and on the environment. The bacterial count in poultry housing systems is particularly high in comparison to those of pigs and cattle. Little is known about the bacteria in the air of new laying hen housing systems. We therefore made simple, simultaneous measurements in the air of three different systems (enriched cages, AK; conventional battery cages, BK; aviary, VOL), in the unheated scratching area of the VOL, and in the outside air over a period of one year (24-h samples were taken about once a month using polycarbonate filters) in order to determine the general bacterial count (using blood agar). The highest concentrations of bacteria were found all year long in the VOL, followed by the BK and the AK. In the VOL, there were on average 2.16 and 0.56 x 10(6) colony forming units (cfu)/m3 in the winter and summer, respectively; 0.25 and 0.38 in the BK; and 0.39 and 0.12 in the AK. These preliminary results show that air quality considerations should be included in the development and implementation of new housing systems, as should the impact on the respiratory system of the humans and animals in them and on the environment, because high concentrations of air contamination in the housing generally also lead to high emissions into the vicinity of the facility, the significance of which cannot always be estimated, as has recently been shown for antibiotics in the exhaust air from animal housing.