Heat stress in cattle causes reduced production, reproductive failure, compromised immune function, and direct welfare harm. Climate change is increasing heat stress prevalence and intensity across global cattle-producing regions.
Heat stress in cattle causes a continuum of welfare harm from subclinical physiological stress to severe suffering and death in extreme events. The metabolic heat load of milk production makes high-yielding dairy cows particularly vulnerable: at peak lactation they generate sufficient metabolic heat to maintain body temperature in cold conditions, which becomes a severe burden in warm weather. Panting (rapid shallow breathing to increase evaporative cooling) is itself energy-intensive and diverts resources from milk production and immune function. Chronic heat stress without adequate relief causes cumulative immune suppression that increases disease susceptibility. Simple interventions with high welfare value include providing shade (natural tree cover or artificial shade structures), water access at multiple points, and active cooling through sprinkler systems. As climate change increases summer temperatures across traditional cattle-producing regions, heat stress mitigation is becoming an increasingly urgent welfare priority.