Heat stress in dairy cattle reduces welfare, milk production, and reproductive performance. Effective cooling is a welfare necessity in warming climates.
Heat-stressed cattle experience physiological distress that affects every aspect of their lives. They reduce feed intake, spend more time standing (reducing resting and comfort), show depressed immune function, and have dramatically reduced fertility. As global temperatures rise, heat stress is becoming a welfare problem in climates where it was previously rare, including the UK. The welfare response requires proactive investment in shade, ventilation, and cooling systems in housing, as well as access to abundant fresh water. Genetic selection for heat tolerance is a longer-term adaptation strategy.