Heat Stress in Poultry: Welfare & Management

Heat Stress in Poultry

Heat stress is a major welfare challenge for poultry globally, increasingly significant with climate change. Chickens, turkeys, and other poultry are highly susceptible to high temperatures and humidity because they cannot sweat — they dissipate heat primarily through panting (respiratory evaporation). Inadequate cooling causes suffering and mortality.

Physiological Response to Heat

• Panting: Rapid shallow breathing increases respiratory evaporative cooling but causes respiratory alkalosis (CO₂ loss).
• Behavioural changes: Wing spreading, seeking shade, reducing feed intake, increasing water consumption.
• Physiological effects: Reduced blood flow to the gut, immune suppression, reduced egg production, shell quality decline, and impaired meat quality.
• Mortality: Severe heat stress causes mortality — acute death from hyperthermia, with broilers particularly vulnerable at high stocking densities.

Risk Factors

• High ambient temperature (>27°C in broilers; lower thresholds for heavy breeds)
• High humidity (combined temperature-humidity index)
• Poor ventilation in intensive housing
• High stocking density
• Fast-growing breeds with higher metabolic heat output
• Dark-feathered breeds absorbing more solar radiation

Welfare Impacts

• Acute suffering from hyperthermia before mortality
• Chronic welfare compromise from repeated sub-lethal heat stress events
• Increased aggression and injurious pecking under heat stress
• Immune suppression increasing disease susceptibility

Management Strategies

• Ventilation: Tunnel ventilation in hot weather; evaporative cooling pads at air inlets.
• Evaporative cooling: Fogging systems to reduce air temperature through evaporation.
• Shade: For outdoor/free-range systems, shade structures and vegetation.
• Feeding management: Adjust feeding times to cooler periods; reduce feed density in hot weather.
• Water: Ensure cool, fresh water is always available; increase drinker provision in hot weather.
• Stocking density: Reduce stocking density in high-risk summer periods.
• Breed selection: Consider heat-tolerant genetics for high-risk climates.
• Emergency protocols: Pre-planned responses to extreme heat events including early thinning.

Key Takeaways

Heat stress is a preventable cause of poultry suffering and mortality. Proactive management of ventilation, stocking density, and water access — combined with emergency response protocols for extreme heat — is essential to protect poultry welfare in a warming climate.