Avian Production Management

HUMIDITY

• The amount of moisture in the air within the incubator is very important to the normal development and subsequent hatching of eggs. In order to create space for growing embryo weight loss of about 12 percent is expected through water loss of hatching eggs during first phase of incubation.
• More weight loss will lead to smaller sized chicks and vice versa. Hence, abnormal fluctuations in humidity during incubation should not be allowed. The excess moisture loss from eggs due to low relative humidity during incubation will result in small and hard chicks while extreme low humidity during actual hatching will lead to embryos dried out in shell or dead in shells.
• Similarly, large and soggy chicks will be produced due to high humidity during incubation with tendency of delayed hatch and lowered hatchability. The chicks may stick to shells.
• The relative humidity is measured by comparative reading of dry and wet bulbs of the thermometer and by calculating the difference of these reading (dry bulb reading – wet bulb reading). Maintaining a relative humidity of approximately 55% under normal conditions prevents excessive moisture loss from the eggs.
• There is an interaction between temperature and humidity during the embryonic process. Higher temperature requires lower humidity and vice versa.