New research from Cornell University has revealed that heat stress affects not only the quantity of milk produced by dairy cows but also its nutritional quality, potentially doubling the economic impact on dairy farmers. An analysis of data from approximately 6.5 million dairy cows across 43 U.S. states between 2007 and 2016 found that rising temperatures and humidity reduce milk fat and protein content, even before noticeable declines in milk yield occur.
Researchers estimated that a 10-point increase in the Temperature-Humidity Index (THI) results in a 1.2% decline in milk production but a 2.8% reduction in annual farm revenue, as milk payments are closely linked to fat and protein levels. The study estimates total industry losses of around US$1.65 billion annually due to combined reductions in milk quantity and quality.
Scientists also found little evidence that dairy cows have become more heat-tolerant over time, regardless of age, farm size, or region. The findings highlight growing concerns over climate change impacts on dairy production and underscore the need for heat-resilient genetics, improved cooling systems, and adaptive farm management strategies to protect milk quality and farm profitability. (Fingerlakes1.com)
Source: Dairynews7x7 23 June, 2026 Read full story here
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