Heat stress in dairy cattle reduces welfare, milk production, and reproductive performance during summer, with evidence-based cooling interventions providing significant welfare and economic benefit.
Dairy cow heat stress causes chronic physiological strain through elevated core temperature, increased respiratory rate, and reduced feed intake. The negative welfare state of heat stress — including reduced lying time, increased water seeking, and altered social behaviour — indicates significant discomfort in affected cows. High-yielding dairy cows generate more metabolic heat than their less productive ancestors, making them more vulnerable to heat stress even at moderate temperatures. Evidence-based cooling with sprinklers and forced ventilation provides immediate welfare relief and is cost-effective in most dairy systems operating in temperate climates experiencing warming summers.