The purpose of the incubator ventilation is to provide sufficient fresh air (oxygen) for the growth and development of the embryo. The embryo needs less oxygen in the early stage and more in the late stage. At the later stage of incubation, the demand for oxygen is 110 times that of the earlier stage. If the oxygen supply is insufficient and the carbon dioxide content is too high, the embryo growth will often be stopped, or the embryo will be deformed. In serious cases, the embryo will die in the process. During the incubation process, the ventilation volume should be increased gradually with the growth of embryo age.

　　The ventilation, temperature and humidity of the incubator are interrelated and mutually restricted. Generally, after the ventilation is strengthened, the humidity will drop, and the temperature will also drop due to the more heat dissipation of the egg. If the air is not circulated, the humidity is high and the egg temperature is easy to rise. When the temperature is high, the humidity is easy to increase, and when the temperature is low, the humidity is small. So when hatching, the three factors should be considered comprehensively and adjusted at any time to make the embryo get the appropriate temperature and humidity. Turning eggs is to change the position and angle of the eggs in hatching in a timely manner. In addition to preventing the adhesion of egg yolk and egg membrane, turning eggs can also promote the activity of embryos. In natural incubation, hens will turn their eggs by themselves. In artificial incubation, people need help to turn eggs regularly. It is better to turn the eggs every 2 to 6 hours, at least 4 times a day. When turning the eggs, it is required to handle them gently, turn them thoroughly, and do not miss them. In the middle and late stages of embryo development, due to the vigorous metabolism of embryo development, a large amount of heat energy should be generated, and the eggs should be cooled regularly. Cool eggs can not only make the breeding eggs emit excess heat, prevent overheating and burn the chicken embryo, but also facilitate ventilation and enhance the adaptability of the chicks to the ambient temperature after they are hatched. Practice has proved that doing a good job in cooling eggs is one of the important measures to avoid overheating and embryo suffocation death in the later stage of incubation. Cold eggs can not only improve the hatching rate, but also improve the healthy hatching rate.