Heat stress is a major welfare problem for dairy cows during UK summers, with increasing frequency as climate changes. Effective heat abatement systems reduce suffering and maintain production performance.
Heat-stressed dairy cows experience a welfare burden that spans physiological, behavioural and productive domains. The discomfort of heat stress is demonstrated by the prioritisation of cooling behaviour over feeding and resting when animals have access to shade or cooling facilities. Chronic heat stress causes immune suppression and increased susceptibility to mastitis and lameness. Reproductive performance deteriorates significantly, with reduced conception rates and early embryonic death. The emotional dimension of heat stress, involving an aversive thermal experience that animals are motivated to escape, represents a welfare concern beyond the measurable production impacts.