Heat stress is a growing welfare problem for cattle in temperate climates as climate change increases frequency and severity of hot periods.
Heat-stressed cattle show increased respiration rates, reduced feed intake, increased water consumption, and bunching in shade. Severe heat stress causes metabolic acidosis, immune suppression, and in extreme cases heat stroke. Pregnant cows suffering heat stress during late gestation produce calves with reduced birth weight, impaired immune function, and lower lifetime productivity. The welfare and production impacts of heat stress make investment in mitigation economically rational as well as ethically important.