Farm Animals

Heat Stress in Dairy Cattle: Impacts and Mitigation

Rising global temperatures make heat stress an increasingly urgent welfare challenge for dairy cows, significantly affecting their health, reproduction, and longevity.

Key Facts

Dairy cows experience heat stress above approximately 25C with high humidity
Heat stress reduces milk yield by 10-25% and conception rates by up to 50%
Elevated body temperature in late gestation harms calf birth weight and immunity
Black-and-white Holsteins absorb more solar radiation than heat-adapted breeds
Shade, sprinklers, and fans can reduce heat load substantially

Welfare Considerations

Heat stress causes a cascade of physiological harms. Cows pant chronically, acidifying their blood and reducing rumen function. They stop eating during the hottest hours, driving negative energy balance. Reproductive performance collapses. Calves born to heat-stressed cows have compromised immune systems that persist for years. As climate change pushes average temperatures higher, heat stress welfare outcomes will worsen without active adaptation.

What You Can Do

Support welfare certification schemes that mandate shade and cooling systems
Advocate for heat stress protocols as a condition of milk procurement contracts
Reduce beef and dairy consumption especially from regions vulnerable to heat stress
Push for breed diversity research that develops heat-adapted high-welfare dairy breeds
Contact your elected officials about climate and agriculture policy linkages