During the incubation process, eggs should be turned, monitored for weight loss and maintained at the correct temperature. If these conditions are not met, the embryo will be weakened and hatching may not occur.
The egg should be stored at cool and humid conditions, such as 55 degrees Fahrenheit with 75% humidity (1). Change the position of the eggs daily to keep them from developing mold and bacteria. Store eggs with the small end pointed downward and leave the larger side up to give the chick space to breathe during incubation.
If an egg is soiled or dirty, it should be removed from storage. Dirty eggs can harbor disease organisms that will cause problems during hatching.
Incubators and hatchers should be thoroughly cleaned, disinfected and fumigated before and after the incubation and hatching cycles to prevent diseases from spreading. The incubator and hatcher should also be kept clean and dry as this reduces the risk of infection.
When the eggs have been positioned, they should be monitored for weight loss and if they are losing too much water, they should be refilled. The amount of water lost depends on the ambient humidity, which should be measured with a wet bulb thermometer or hygrometer and recorded. If the reading is too low, the humidity should be increased.
During incubation, it is vital to keep the air inside the egg shell moist, which can be accomplished by adding water or by using an artificial source of humidity. If the air becomes too dry, it can cause the shell to crack and the chick can die of dehydration.
A psychrometric chart or an online calculator can help you determine the ideal humidity level for the chicks to hatch. It is best to use a hygrometer for the purpose of monitoring the humidity, as dry-bulb thermometers can become inaccurate with time and are difficult to read at high temperatures.
If you have an automatic incubator, turn the eggs manually every hour or so. Many automatic incubators have a turning mechanism such as tilting shelves or egg carriers, rotating discs and moving floors; some are fully programmable.
In addition to the normal turning of the eggs, it is necessary to rotate them once a day so that the embryo does not stick to the yolk or albumen and causes injury to the chick. In addition, the embryo can be squeezed between the yolk and the shell if it is not turned and this is the leading cause of death during incubation.
The embryo will naturally move as the fetus grows in size. This is a natural part of the hatching process and it is best not to help the chick by pecking at its shell or pulling it out of the egg, as this can cause injury.
The fetus will be ready to hatch when it has reached about 19 days in incubation. When it has reached this point the embryo instinctively starts lung respiration. This is the first step towards a healthy, fully developed chick. The fetus will then peck at its large end and take its first breath, which can be seen as a bubble of air within the egg. Once the chick has taken its first breath, it will usually stay still for about six to 12 hours before continuing on its journey.