Heat stress in cattle causes significant welfare compromise, reduced productivity, and mortality during extreme weather events. Climate change is increasing both frequency and severity of heat stress events.
Heat stress is both an acute welfare emergency and a chronic welfare condition that affects cattle across months of warm weather in affected climates. Physiologically, heat stress triggers a cascade of metabolic changes including reduced feed intake, altered rumen function, elevated cortisol, and impaired immune function that collectively cause suffering and increase disease susceptibility. Severely heat-stressed cattle pant continuously, seek shade aggressively, and show altered social behaviour — these are visible welfare indicators. Climate change is making heat stress a more frequent and severe welfare challenge in production regions previously considered temperate. Mitigation strategies — shade provision, sprinklers, ventilation, and altered feeding timing to cooler periods — are increasingly necessary as baseline requirements rather than optional additions. Breed selection toward heat-tolerant genetics is a longer-term adaptation strategy.