Quantification of bioaerosols in automated chicken egg production plants.

The quantity and composition of bioaerosols in a typical automated chicken egg layer management system (LMS) with a controlled internal climate (B) and without (A) were compared. The LMS-A used a fecal matter disposal system featuring a central opening in the floor through which the matter automatically dropped to an open-air lower level; the LMS-B used a conveyer belt below each hen battery set, which removed the fecal matter frequently. Bioaerosols were collected by impaction on agar. Humidity, wind velocity, temperature, and dust particle concentration were also analyzed at several locations in the LMS. The average bioaerosol concentrations (total viable aerobic bacteria) associated with the inside of LMS-A reached X = 1.1 x 10(5) cfu/m3 with counts in LMS-B being X = 9.2 x 10(4) cfu/m3. In both systems, the bacterial counts were significantly higher on the inside of the LMS than the outside. The LMS-A showed yeast counts of X = 6.7 x 10(1) cfu/m3 with none detectable in LMS-B. Total culturable mold counts were X = 7.0 x 10(2) cfu/m3, with significantly higher presumptive Salmonella spp. counts (X = 6.6 x 10(1) cfu/m3) inside both LMS when compared with the outside. Escherichia coli and total culturable gram-negative counts were significantly higher in LMS-B at concentrations of X = 3.6 x 10(1) cfu/m3. These counts were significantly higher compared with the outside environment. We concluded that the live birds were the major source of bioaerosols in both LMS, with the fecal matter disposal systems attributing to the difference in bioaerosol composition. Modifications to the operation protocols of both LMS to limit the contamination of eggs by bioaerosols are suggested.