Climate change is increasing the frequency and intensity of heat stress events in dairy cattle globally. Heat stress causes significant welfare harm and is now recognised as a major management priority.
Heat-stressed dairy cows experience prolonged discomfort that progressively worsens throughout hot spells. Panting and sweating reduce hydration; reduced feed intake causes metabolic stress on top of environmental stress. In severe heat events, body temperature rises to dangerous levels causing organ damage and potentially death. High-yielding cows produce more metabolic heat through digestion and milk synthesis, making them more susceptible than lower-producing animals. Climate change means that heat stress events that were once occasional are becoming seasonal challenges requiring infrastructure investment and management adaptation.