Though evaporative cooling is used around the world to keep birds cool during hot weather, by itself it is not a very effective method of reducing bird heat stress. To understand why, one must understand how a bird cools itself. Poultry feed is rich in energy/calories (similar in energy density to chocolate cake with frosting). The energy in the feed is used by the birds to grow, produce eggs, move, as well as, power the basic functions of life (breathing, pumping blood, maintaining body tempera...ture, immunity, etc.). Though we view birds as very efficient animals, the fact is that only 25% of the energy in the feed consumed is actually used for these functions, the remaining 75% is essentially put off in the form of heat – heat a bird must rid itself of in order to maintain normal body temperature and survive.