Energy requirements for maintenance as a function of body weight and critical temperature in broiler chickens

•The thermoneutral zone reduces according to body weight increase.•Maintenance energy requirements depend on body weight, upper or lower critical temperature, and environmental temperature.•The change in maintenance energy requirements outside the thermoneutral zone are 2.70 and 4.07 kcal/kg0.75( °C × d) for temperatures below and above the thermoneutral zone, respectively.