A dirty incubator or hatchery area is a major source of contamination and disease. Thoroughly wash and disinfect the hatching unit after each use with a quaternary ammonium compound or commercial disinfectant. Set only clean eggs, as dirty eggs are a source of disease or infection. Soiled eggs can best be cleaned with fine sandpaper or other abrasives — eggs to be incubated should not be washed.
Eggs should be fumigated after they are collected, but alternatively they can be fumigated within 12 hours after being placed in the incubator. Do not fumigate embryos that are between 2 and 5 days old. Fumigation procedures are as follows:
* Use 25 g of potassium permanganate and 35 mL of formalin (40%) for each cubic metre of incubator space.
* Put the permanganate in an earthenware or enamelware dish (volume ten times that of the ingredients), and add the formalin last. Avoid inhaling the fumes, or wear a suitable respirator.
* In forced-draft incubators, leave the fan running and the vents closed during fumigation; open the vents after 20 minutes.
* In still-air incubators, open the incubator and vent after 20 minutes.
* During fumigation the humidity should be high, and the temperature must be between 20°C and 30°C.