Heat Stress in Cows: Hot Days Lead to Significant Milk Production Decline

Heat stress has emerged as a critical factor affecting dairy cows, with new research indicating that a single hot day can reduce milk production by up to ten percent. The implications of this study, published in the journal Science Advances, suggest that the effects of heat stress can linger for up to ten days following extreme temperatures.

The research team, led by scientists from the Hebrew University of Jerusalem, highlights a concerning trend linked to climate change: a potential decrease in milk output across the globe. They predict that without effective measures to curb greenhouse gas emissions, dairy cows in the world's top ten milk-producing countries could yield up to four percent less milk between 2045 and 2055, with Germany facing a potential loss of approximately 1.4 percent.

The study analyzed data from the Israeli Cattle Breeders Association, spanning from 2009 to 2020. This data was cross-referenced with weather conditions and the heat stress mitigation strategies implemented by farmers. The findings reveal that dairy farmers are increasingly aware of the detrimental impact of heat stress on their herds and are adopting various cooling techniques.

Common strategies include the use of fans and misting systems to alleviate heat stress. However, the research indicates that even with these interventions, significant production losses remain unavoidable. The study found that after a single hot day, it takes about ten days for milk production levels to return to normal. During this recovery period, cumulative losses can reach up to 25.6 percent compared to periods without extreme heat.

In the past two decades, many Israeli dairy farmers have taken proactive steps to protect their animals from heat stress, often housing them in shaded areas that are open to the surrounding environment. While these methods can help mitigate losses, they do not completely eliminate them.

Researchers emphasize that the dairy sector in Israel serves as a valuable case study due to the varied climate conditions across the country, which mirror those found in leading milk-producing nations worldwide. The findings underscore the urgent need for the dairy industry to adapt more effectively to the challenges posed by climate change.

As temperatures continue to rise globally, the study's authors warn that even the most advanced and well-equipped dairy operations may struggle to keep pace with the increasing demands of climate resilience. They urge the industry to explore more robust solutions in order to safeguard future milk production.