Heat Stress in Broiler Chickens: A Growing Welfare and Production Crisis

Heat stress is a leading cause of suffering and mortality in broiler chickens globally. Climate change is intensifying the problem, with significant welfare implications for tens of billions of birds annually.

Key Facts

Broiler chickens are highly susceptible to heat stress due to their fast growth rate, large muscle mass, and limited thermoregulatory capacity
Heat stress above 32°C causes panting, reduced feed intake, wing-spreading, and death in severe cases
An estimated 20–30% reduction in feed conversion efficiency occurs during heat events, indicating significant metabolic stress
Tropical and subtropical producing countries — which produce the majority of global broiler meat — face the highest heat stress burden
Evaporative cooling systems reduce mortality in severe heat events but are unavailable on most commercial farms globally
Climate models project a 2–4°C increase in average temperatures in major broiler producing regions by 2070
Fast-growing breeds are significantly more heat-sensitive than slow-growth alternatives due to higher metabolic heat production

Welfare Considerations

Heat stress in broilers causes a spectrum of welfare impacts from mild discomfort at moderate temperatures to acute suffering and death during severe heat events. The welfare challenge is structural: fast-growing breeds generate excess metabolic heat, high stocking densities impair ventilation, and infrastructure in major producing countries often lacks cooling capacity. The compounding effect of climate change makes this a worsening problem without deliberate intervention. Welfare improvements include transitioning to slower-growing breeds with lower metabolic heat output, mandatory ventilation and cooling standards, reduced stocking density (particularly during summer months), and emergency protocols for heat event responses. These interventions are individually feasible but require regulatory mandates to achieve widespread adoption.

What You Can Do

Support Better Chicken Commitment and equivalent standards that require slower-growth breeds less susceptible to heat stress
Advocate for mandatory heat stress emergency protocols and ventilation standards in broiler welfare regulations
Reduce broiler chicken consumption, particularly from producers in tropical regions without documented heat stress management
Support research into heat-tolerant broiler genetics that maintain welfare without compromising sustainability
Donate to organisations working on climate adaptation in animal agriculture with a welfare lens