By Alina Corey
Hot weather can severely impact poultry performance. Heat stress in poultry typically begins when the ambient temperature climbs above 80 degrees Fahrenheit and becomes very apparent at temperatures around 85 degrees Fahrenheit. When a bird begins to pant, physiological changes have already taken place within its body to help eliminate excess heat. Practicing proper heat management to help keep birds comfortable will help maintain optimum growth, hatchability, egg size, egg shell quality, and egg production.
When temperatures reach mid- to upper 90s, it is important for birds to be able to dissipate body heat to maintain a body temperature of about 105 degrees Fahrenheit. However, poultry do not sweat. Therefore, body heat is dissipated from wattles, shanks, and unfeathered areas under the wings. Birds do not need to drastically alter normal behavior, feed intake, or metabolism to maintain body temperature by heat loss. The purpose of ventilation in poultry housing is to maintain an environment that allows birds to sustain body temperature by sensible heat loss. Sensible heat loss methods include radiation, conduction, and convection which are effective when temperatures range from 55 to 75 degrees Fahrenheit. Once temperatures reach 77 degrees Fahrenheit, the method for heat loss shifts to evaporative heat loss. Evaporative heat loss requires birds to dissipate body heat by panting, which begins to occur at about 80 degrees Fahrenheit.