Heat Exchange between Animal and Environment

As a result of its metabolic activity, an animal produces heat. The rate at which heat is produced bears a direct relation to the metabolic rate measured as oxygen consumption. For this reason the two rates are often considered as relating to the same quantity and as being interchangeable, provided the animal is not doing external work. Although “metabolic rate” and “heat production” may have the same meaning, they are not necessarily of the same magnitude as heat loss. The rate of heat loss from an animal is determined by the rate of heat production and the rate at which heat is being lost from or stored in the body as the result of changes in the temperatures of its parts: $$M = H + S$$ (2-1) where M = rate of heat production, or metabolic rate H = rate of heat loss S = rate of change of stored heat