Milk composition responses amplify economic damages from heat stress

Heat stress affects more than milk yield—it also reduces milk quality, with major economic consequences. Using data from over 6.5 million U.S. dairy cows, researchers found that while milk yield declines mainly when THI exceeds 70, milk fat and protein content decrease progressively as heat load increases. Accounting for both quantity and quality losses revealed that heat stress costs are at least twice as high as estimates based on milk yield alone, highlighting the broader impact of climate change on dairy production.

By Prieto J., Lin Z., Reed K.F. et al.