The period from hatching until the chickens no longer require supplementary heat is called the ‘brooding period’ and usually lasts for 3–6 weeks, depending on seasonal temperatures and the type of housing.
Chickens need supplementary heat when they hatch, because they are unable to maintain their body temperatures. The heat can be supplied by a broody hen or, more usually, by brooders fuelled by electricity, gas or oil.
As the chicken grows, its downy coat is replaced by feathers, and the brooding temperature can be gradually reduced, until supplementary heat is discontinued at about 3–4 weeks.
During the brooding period, the chickens need warmth, shelter, fresh air, proper food and clean water.