Heat stress is a major welfare and production problem in broiler chickens, causing suffering, mortality, and significant economic losses particularly as global temperatures rise.
Heat stress in broilers creates a welfare crisis that compounds the pre-existing cardiovascular vulnerabilities of fast-growing breeds. A broiler already living on the physiological edge of cardiac capacity experiences acute additional stress when ambient temperatures rise — panting increases respiratory rate from 25 to 200 breaths per minute, and birds may die from heat prostration within hours in extreme conditions. The welfare problem is worsened by high stocking density: birds cannot distribute in the pen to find cooler areas, and each bird generates metabolic heat that compounds ambient temperature effects. Effective welfare management requires investment in tunnel ventilation systems, evaporative cooling, and reduced summer stocking densities. Water access is particularly critical — a bird that cannot reach a drinker during heat stress can die within 2-4 hours. Monitoring mortality rates as a welfare indicator and having emergency protocols for extreme heat events are minimum requirements for responsible production.