The egg racks are placed in a room and disinfected with formalin. Cadirci (2009; Archiv für Geflügelkunde 73; p 116-123) has published a review on this treatment. Using formalin eliminates only bacteria on the shell. Therefore eggs are ready to enter the next step of the process.
Except fumigation, there are more ways to treat eggs before setting in the brooders.Ralph A. Ernst, (Extension Poultry Specialist, Animal Science Department, University of California, Davis, CA 95616) discussed some of them.
Fumigation : Formaldehyde gas fumigation has long been used to reduce contamination on eggs. Label registration for this use was withdrawn for a time due to its potential human toxicity but EPA has again registered several formaldehyde products for incubator and hatching egg fumigation. However, at this time no formaldehyde product is registered in California for this use.
Spray Application: Solutions containing disinfectants can be sprayed onto clean eggs during collection. Any disinfectant registered for use on hatching eggs can be used.
Check with local suppliers for registered materials and use them at recommended levels.
UV Light: Eggs can be sanitized with UV light. Commercial sanitizing equipment utilizing UV light is available for commercial producers.
Egg Washing: Some producers prefer to wash hatching eggs. Egg washing effectively sanitizes hatching eggs if proper equipment is available to do the job correctly. However, washing can cause contamination of eggs if the water temperature drops below recommended levels or if contamination exceeds the capacity of the disinfectant (a particular concern in reservoir-type or immersion washers). Wash water must always be hotter than the eggs (recommended range, 110oF to 120oF). The washing solution must contain an appropriate sanitizer. A washer that does not recirculate water is recommended. If an immersion washer is used, the water must be changed frequently; do not wash more than 200 eggs per gallon of solution capacity before changing the washing solution. Immersion time should not exceed 3 minutes and eggs should be thoroughly dry before they are put into cases. To be most effective, reservoir-type washers should be equipped with systems to monitor and control sanitizer levels. This type of washer should have a final sanitizing rinse with a solution that is not recirculated. Several commercial egg washing machines are available that will effectively sanitize hatching eggs when used properly. Only good quality water with less than 2 ppm iron should be used for egg washing.
Disinfectants for Egg Sanitation:Several commercial products are registered for hatching egg sanitation. You can find an extensive list of disinfectants at: http://www.biosecuritycenter.org/disinfect.htm.
Chlorine-based disinfectants containing a cleaning agent are widely used to wash table eggs and have proved safe for hatching egg sanitation. There are several commercial disinfectant formulas registered for hatching egg washing. University of California research has shown quaternary ammonium to be an excellent sanitizer for hatching eggs. The advantages of quaternary ammonium are that it: 1. Is safe for hatching eggs. 2. Leaves residual protection on eggs. 3. Is safe for equipment and personnel. 4. Is reasonable in cost.