The first days of a chicken's life are known as the brooding period. In this period, important developmental and physiological processes occur. Although the bird is anatomically complete at the day of hatch, the digestive, immune and thermoregulatory systems are not fully developed yet.
In this period a chicken cannot regulate its own body temperature. If environmental variables, such as air temperature and air velocity, are not optimum, it will have a direct affect on the chicken's body temperature. If this body temperature is too high or too low, a chicken will not start eating and drinking and/or will suffer from stress. The first days of a chicken's life are decisive for the technical results subsequent to the growing period. The chicken strongly depends on the ambient conditions provided by its carers (poultry farmers)