The other occasional Salmonella serotypes such as Salmonella Schwarzengrund, Salmonella Madelia, Salmonella Montevideo, and Salmonella Enteritidis were isolated. The experimental group receiving formaldehyde by constant rate infusion during hatching had a significantly superior inhibitory effect on aerosol bacterial count 4 h before hatching as compared with the group receiving formaldehyde into a basin and the negative control group (P < 0.05).