Recorded live at the American Dairy Science Association (ADSA) Annual Meeting, this episode of the Real Science Exchange explores an increasingly important challenge for the global dairy industry. Specifically, it asks: how can we move beyond simply managing heat stress and begin building more resilient dairy cows and production systems?
Episode 223: Strategies to Improve Heat Stress Resilience in Dairy Cows
Timestamps:
The conversation brings together the speakers from the symposium, “Concepts and Strategies to Improve Physiological Resilience to Heat Stress in Dairy Cows”. The speakers are Dr. Yun Jiang, University of Wisconsin-Madison; Dr. Jimena Laporta, University of Wisconsin-Madison; Dr. Vincenzo Lopreiato, University of Messina; and Dr. Maya Zachut, Volcani Institute.
Together, the panel explores dairy cow heat stress, physiological resilience, immune function, cooling strategies, nutrition, oxidative stress, calf development, and early-life management. Furthermore, their discussion highlights an important takeaway for dairy producers and nutritionists. In summary, cooling remains essential, but combining effective management with targeted nutrition throughout the animal’s life offers additional opportunities to support resilience.
Understanding Heat Stress and Dairy Cow Resilience
The episode begins with introductions from the panel. Dr. Jiang discusses her work in dairy nutrition, stress mitigation, and sustainability. Meanwhile, Dr. Laporta shares her research background and path from the University of Florida to the University of Wisconsin-Madison. Dr. Lopreiato, based at the University of Messina in Sicily, also introduces his work with dairy cow heat stress. (00:00 – 03:48)
The discussion then examines why heat stress in dairy cattle is a global challenge. Dr. Zachut explains that cows in Israel are now considered heat stressed for eight months of the year. She also notes that heat stress has become relevant even in northern regions. Even advanced cooling systems cannot completely alleviate its effects. Therefore, it is important to consider physiology, management, and nutrition together. (03:49 – 09:19)
Why Are Some Dairy Cows More Resilient to Heat Stress?
Dr. Jiang shares research examining why individual cows respond differently to heat stress. Some cows demonstrated greater resilience, with smaller declines in milk production and smaller increases in body temperature. These resilient cows also produced less methane and experienced lower levels of inflammation, pointing to potential differences in energy metabolism. She notes that the 64-cow study was not large enough to conduct genetic analysis, leaving important questions for future research. (09:20 – 11:58)
Heat Stress in Calves and the Importance of Early-Life Cooling
The conversation shifts from the lactating cow to the dry cow and what Dr. Laporta describes as the “transition calf.” She explains that heat stress during the first 60 to 90 days of a calf’s life can affect development of the mammary gland, ovary, thymus, and spleen.
Cooling pre-weaned calves improved survival and slightly increased milk production when those calves later entered the milking herd. For dairy producers facing replacement shortages, Dr. Laporta identifies early-life cooling as a practical opportunity. In her view, this supports the development of more resilient animals. (11:59 – 19:37)
Combining Dairy Cow Cooling Strategies with Targeted Nutrition
Dr. Zachut discusses a 2×2 study comparing three versus six cooling sessions per day in mid-lactation dairy cows, both with and without beta-caryophyllene, a dietary cannabinoid. She found that increasing cooling improved welfare, behavior, and milk production but had surprisingly little impact on immune function following an intramammary LPS challenge. Moreover, the combination of the highest level of cooling and dietary supplementation demonstrated synergistic effects. (19:38 – 26:10)
Methionine, Oxidative Stress, and Heat-Stressed Dairy Cows
Dr. Lopreiato explores the potential role of methionine and plant polyphenols in supporting antioxidant defenses during periods of heat stress. He notes that even when efficient cooling strategies are used, milk production losses can still reach 15%. This suggests that cooling alone may not address every physiological consequence of heat stress.
The discussion highlights oxidative stress as a potential contributor to heat stress damage and examines how nutritional strategies may complement traditional cooling approaches. (26:11 – 32:18)
Supporting Immune Function During Heat Stress
Rather than simply suppressing the immune response, the panel emphasizes the importance of fine-tuning immune function in heat-stressed dairy cattle.
Dr. Zachut describes cooling as the strongest strategy available, while noting that cows receiving three cooling sessions per day along with the dietary supplement demonstrated resting times similar to cows receiving six cooling sessions. The conversation also explores capsaicin-containing extracts and their potential ability to increase sweating. Additionally, Dr. Lopreiato emphasizes the importance of rumen protection when considering nutritional approaches. (32:19 – 38:47)
Heat Stress and Immune Function in Dairy Calves
The panel returns to the effects of heat stress during early life. Dr. Laporta explains that heat stress can activate a calf’s immune system while simultaneously making that response less effective. In this context, she notes there is lower neutrophil function and increased illness.
Dr. Zachut also identifies young calves as an interesting opportunity for nutritional intervention. She explains that certain compounds, including polyphenols, can potentially be provided before the rumen becomes fully functional. (38:48 – 43:53)
Building More Heat-Resilient Dairy Herds
The episode concludes with each researcher reflecting on where heat stress research and management may go next.
Dr. Zachut notes that even the best-cooled dairy farms continue to experience losses in areas such as fertility and immune function. Dr. Jiang raises an important nutritional question: Do heat-stressed dairy cows have different nutrient requirements? Meanwhile, Dr. Laporta emphasizes that there is no single solution to heat stress. She notes that early-life management should be part of the discussion when developing dairy cows capable of adapting to a changing climate. (43:54 – End)
Across the conversation, one message remains clear: cooling is essential, but cooling alone is not enough. Therefore, combining effective cooling and management practices with targeted nutrition, while considering resilience across every stage of the animal’s life, may provide greater opportunities. This combination can support dairy cow health, productivity, and long-term resilience.
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