To evaluate bacterial contamination of the air sample, 3 sites evenly arranged in each hatcher were sampled every 4 h during transfer to chick removal. Plate count agar prepared to evaluate the aerobic bacteria was exposed for 1 min. After transportation to the laboratory, the plates were incubated at 37°C for 48 h and then the colonies on the plate surfaces were counted and found to yield colony-forming units/63.6 cm2.