Broiler Heat Stress: When Fast Growth and High Temperatures Combine

Modern broiler chickens are extremely vulnerable to heat stress because their rapid growth and large muscle mass generate more body heat than they can dissipate, making temperature management a critical and often inadequately met welfare need.

Key Facts

Broiler chickens cannot sweat and rely entirely on panting to regulate body temperature, which is far less efficient
Modern fast-growing breeds generate 30-40% more body heat than slower-growing heritage breeds due to their metabolic demands
Heat stress begins at temperatures above 25-27 degrees Celsius in broilers — well within normal summer temperatures in many production regions
Acute heat stress causes panting, prostration, seizures, and death; chronic heat stress suppresses immunity and increases disease vulnerability
Global warming is making heat stress events more frequent and severe, with mortality events of thousands of birds per flock now common
Cooling systems including tunnel ventilation, evaporative cooling pads, and cool drinking water can significantly reduce heat stress mortality
The transition to slower-growing breeds substantially reduces heat stress vulnerability as part of wider welfare improvements

Welfare Considerations

Heat stress in broilers represents a convergence of welfare problems: a breed with inherently poor thermoregulation, housed at high densities in barns where metabolic heat from thousands of birds accumulates, facing increasingly hot summers due to climate change. Deaths from heat stress represent only the visible tip of a larger welfare problem — chronic heat stress throughout the production cycle suppresses immunity, reduces activity, and causes suffering that does not show up in mortality statistics. Addressing broiler heat stress requires both improved housing systems and the transition to slower-growing, more physiologically robust breeds.

What You Can Do

Support campaigns advocating for mandatory tunnel ventilation and temperature monitoring in broiler houses
Choose chicken from producers using slower-growing breeds such as those certified under the Better Chicken Commitment
Advocate for maximum stocking density reductions in broiler houses to reduce internal heat load
Support climate policies that reduce the frequency of extreme heat events affecting livestock welfare
Ask retailers about their heat stress protocols and stocking density standards for broiler suppliers
Donate to organisations researching climate-resilient poultry breeds and housing systems
Reduce chicken consumption during summer months when heat stress welfare problems are most acute in your supply chain