By: Tony Unandar*

Heat stress is not merely a matter of high temperature; rather, it results from a complex interaction among temperature, humidity, ventilation, stocking density, and the bird’s physiological ability to dissipate body heat.

The prevalence of heat stress in modern poultry is becoming increasingly common and has emerged as a major challenge for the poultry industry. Its impact extends beyond reduced production performance to increased depletion rates, ultimately leading to significant economic losses. Amid climate change and global warming, an important question arises: Is heat stress truly caused solely by high environmental temperatures or humidity?

In reality, heat stress is a far more complex condition. Environmental factors, management practices, and the physiological responses of birds all interact to determine whether a chicken experiences heat stress. This article discusses the mechanisms underlying heat stress based on scientific studies, enriched by the author’s field experience, while also exploring prevention strategies and measures to minimize its risks.

Physiology and Pathogenesis of Heat Stress

As members of the class Aves, chickens are homeothermic animals, meaning they are capable of maintaining a relatively constant body temperature despite changes in environmental conditions. This capability is made possible by a complex thermoregulatory system involving the anterior hypothalamus, the preoptic area of the cerebrum, the vagus nerve, and temperature receptors distributed throughout peripheral tissues.

Heat energy originating either from body metabolism or the surrounding environment is detected by these temperature receptors. The information is then transmitted to the brain’s thermoregulatory center, which initiates appropriate physiological responses, enabling the bird to maintain thermal balance (Lin & Decuypere, 2005).

This mechanism explains why the effective temperature—the temperature actually perceived by the bird—does not always correspond to the actual temperature measured by a thermometer. In other words, the temperature displayed by measuring instruments may not accurately reflect the bird’s true level of comfort.

Therefore, evaluating poultry house conditions should not rely solely on environmental temperature readings. Routine observation of bird behavior is often a much more important indicator for detecting the early signs of heat stress.

Several factors can cause the effective temperature to be higher than the actual temperature. These include elevated ambient temperatures, increased humidity, excessive stocking density, inadequate ventilation, and low air velocity. Such conditions hinder the bird’s ability to dissipate body heat, making chickens more susceptible to heat stress.

This article is an excerpt from the Health section of Poultry Indonesia Magazine, July 2026 edition. Read the full article in Poultry Indonesia Magazine July 2026 edition. For subscriptions or further information, contact +62 877-8012-0754 or sirkulasipoultry@gmail.com.

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