New research from Cornell University has revealed that heat stress affects dairy farmers more severely than previously understood by reducing not only milk production but also the fat and protein content of milk. Analyzing data from approximately 6.5 million cows and around 120 million milk production records across the United States between 2007 and 2016, researchers found that milk quality begins to decline even at temperatures that do not significantly impact milk volume.
The study showed that a 10-point increase in the temperature-humidity index reduced annual milk yield by just over 1%, but cut farm revenue by nearly 3% because dairy farmers are paid largely based on milk fat and protein content. Researchers estimate the combined economic impact at approximately US$1.65 billion for the U.S. dairy sector, with the decline in milk composition causing losses comparable to those from reduced milk volume.
The study also found little evidence that cows, farms, or regions have significantly adapted to heat stress, suggesting that decades of breeding for higher productivity may have increased vulnerability to warming conditions. Scientists say the findings highlight the need for greater focus on heat-tolerant genetics, improved herd management, and climate adaptation strategies as rising temperatures continue to challenge dairy production worldwide. The research was published in the journal Environmental Research Letters. (Earth.com)
Source: Dairynew7x7 23 June, 2026 Read full story here
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