PHYSIOLOGICAL REACTIONS OF POULTRY TO HEAT STRESS AND METHODS TO REDUCE ITS EFFECTS ON POULTRY PRODUCTION

Abstract

Thermal environment is regarded as the prime factor governing the production because, both the feed consumption and heat production are related closely to the thermal environment. Therefore, heat stress is caused by a combination of environmental and animal factors that result in reduced performance as the animal attempts to cool itself. In this review, the physiological reactions of bodily functions during heat exposure in poultry are described. Thermal panting, the marked response of poultry to heat stress, is compensatory behavior to permit a high rate of evaporative cooling from the respiratory tract. Cardiorespiratory responses to thermal stress show different patterns among birds that are experienced or inexperienced with high ambient temperature. The effect of
heat stress on changes of body fluids and renal function of poultry are reviewed. A number of methods to reduce heat stress on poultry production are presented along with various management considerations, including water management, dietary adjustments, increasing heat tolerance through the process of acclimation, designing mineral
drinking water supplementation and designing rations for correcting the acid-base imbalance. The beneficial effects of supplemental anti-stress agents (e.g., ascorbic acid) in reducing heat stress are also noted.