Heat stress in dairy and beef cattle causes significant welfare problems and production losses, with climate change increasing frequency and severity of heat events.
Cattle experiencing heat stress show elevated respiration rates, increased water intake, reduced feeding and rumination, and clustered standing behaviour indicating thermal discomfort. Chronic heat stress impairs immune function, increasing susceptibility to mastitis and other infections. Reduced rumination activity in heat-stressed cows leads to acidosis risk. Fertility impairment from heat stress causes prolonged anoestrus and reproductive stress. Zero-grazing systems housing cows indoors require active cooling management to prevent heat stress.