Bacterial Counts and Physical Properties of Hatching Eggshells Sprayed with a Formaldehyde Solution

Poultry companies must implement measures to sanitize hatching eggs and reduce the risk of bacterial infections associated with poultry management. Many of them use formaldehyde (FA) fumigation in their egg sanitization protocols, but its toxicity has led to recommendations for reducing its use. However, studies employing this approach with liquid FA solutions in poultry operations, particularly during the hatching egg sanitization stage, remain scarce. Our objective was to evaluate whether sprayable FA reduces bacterial contamination on eggshells and whether it causes changes in their physical properties based on the analysis of microstructure, percentage relative to egg weight, and thickness. FA solutions at 0.5, 1, and 2% inhibited bacterial growth in vitro and reduced the bacterial load on the eggshell surface while also causing severe damage to the shell structure. Our results suggest that companies using FA should be aware of the associated risks, as significant production losses may be linked to the shell damage caused by this compound.