Heat Stress in Poultry: A Comprehensive Review of Thermoregulation and Physiological Responses

Heat stress poses a significant challenge in poultry production, impacting bird health, productivity, and overall welfare. This review explores the physiological and biochemical effects of heat stress on poultry, emphasising its impact on feed intake, egg production, and immune function. It highlights key thermoregulatory mechanisms, including conduction, convection, radiation, and evaporation, which birds employ to maintain homeostasis. Additionally, the role of stress-related hormones and metabolic adjustments in response to elevated temperatures is discussed. These physiological alterations collectively reduce feed intake, growth rate, eggshell deposition, egg quality, and overall performance, with chronic exposure leading to significant mortality. The reviewed findings illustrate that heat stress is not a single-pathway disturbance but a multisystem disruption spanning metabolic, endocrine, immune, and behavioural domains.