Heat Stress in Poultry: Welfare Impacts and Climate Adaptation

Heat stress is a major welfare and production problem in commercial poultry, causing suffering, reduced growth, increased mortality, and compromised egg quality. As global temperatures rise, heat management is becoming a critical welfare frontier.

Key Facts

Poultry cannot sweat — they rely on panting and behavioural responses to regulate body temperature
Broiler chickens are particularly vulnerable due to large body mass, rapid growth, and high metabolic rate
Heat stress begins at approximately 27°C in broilers — temperatures regularly exceeded in commercial housing during summer
Mortality during heat events can reach 1-5% of flock population in severe episodes, representing millions of birds
Chronic heat stress reduces feed intake, growth rate, and immune function, increasing susceptibility to disease
Effective mitigation includes evaporative cooling systems, tunnel ventilation, reduced stocking density, and early morning feeding schedules

Welfare Considerations

Acute heat stress causes visible distress — panting, wing spreading, lethargy, and in severe cases, collapse and death. Chronic subacute heat stress is subtler but causes sustained welfare compromise: reduced feed intake, altered gut microbiome, immunosuppression, and increased susceptibility to footpad dermatitis from reduced activity. Fast-growing broiler breeds are disproportionately vulnerable because their high metabolic rate generates body heat that compounds ambient temperature. Climate change is expanding both the geographic range and intensity of heat events affecting commercial poultry, making infrastructure investment in cooling systems an urgent welfare requirement, not merely a production optimisation. Heat welfare standards in outdoor and free-range systems require particular attention because shade and shelter provision is inconsistently regulated.

What You Can Do

Choose poultry from farms with documented ventilation and cooling standards, particularly for summer production
Support legislation mandating minimum ventilation and temperature standards in all commercial poultry housing
Advocate for poultry housing to be subject to climate risk assessment as part of planning and licensing
Reduce poultry consumption or switch to higher-welfare certified products to create market pressure for infrastructure investment