Dietary approaches to mitigate heat stress in dairy cows are promising because the gastrointestinal tract is the initial pathway for many health issues that threaten an animal’s health and performance. Nutritional interventions can be easily implemented into farm operations and generally do not require expensive structural capital investments.
Category Director Trace Minerals
Trouw Nutrition
While much research has explored the adverse effects of heat stress on dairy cows’ gastrointestinal tracts, comparatively little study has focused on the role that trace minerals can play to help livestock recover from heat stress.
Below, we look at the challenge of mitigating heat stress on the dairy farm and review a study that explored how swapping a trace mineral source can help cows recover from heat stress.
HEAT STRESS: A CONCERN FOR ANIMALS AND FARMS
As global temperatures increase, heat stress is a costly concern for dairy herds. Among livestock producers, heat stress imposes the largest losses on the dairy industry (St-Pierre et al. 2003, Ke and Sneeringer, 2014).
Heat stress can occur when dairy cows are exposed to high temperatures and humidity, leading to increased body temperatures and respiratory rates. These effects become more pronounced as temperatures rise, and can lead to decreased milk production, compromised health, and increased economic losses for farmers.
One of the most noticeable consequences of heat stress is a reduction in feed intake, while other problems are harder to observe. Inside the animal, heat stress disrupts the gastrointestinal tract (GIT) barrier, causing hyperpermeability, inflammation, and altering of the animal’s metabolism. Whether visible or not, the consequences of heat stress in dairy cows are significant. Issues can show up as lower milk yield, higher health costs on the farm, or an animal’s shortened time in the productive herd.
A DIETARY APPROACH TO HELP ANIMALS RECOVER FROM HEAT STRESS
Science-based nutrition is a strategy producers can use to support dairy cows’ recovery from heat stress. Dietary approaches to mitigate heat stress in dairy cows are promising because the gastrointestinal tract is the initial pathway for many health issues that threaten an animal’s health and performance. Nutritional interventions can be easily implemented into farm operations and generally do not require expensive structural capital investments.
A research trial conducted by the Department of Animal Science at Iowa State University in collaboration with Selko looked at how switching from a sulfate to Selko® IntelliBond® Zinc (Zn) source can mitigate the adverse effects of heat stress in dairy cows. Selko® IntelliBond® Z is a hydroxychloride trace mineral with a crystalline structure and covalent bond. This structure is designed to make minerals less soluble and more available to the animal compared to sulfate minerals.
Researchers hypothesized that replacing Zn sulfate with Selko® IntelliBond® Z in dairy cow diets would be an effective dietary practice to mitigate heat stress-induced GIT pathology and systemic inflammation in lactating Holstein cows.
In the trial, researchers evaluated the effects of a sulfate Zn mineral and Selko® IntelliBond® Z on metabolism, inflammation, and GIT permeability during and following heat stress. The trial involved 24 mid-lactation Holstein cows, divided into two groups: One group received a control diet with Zn sulfate and the other group was supplemented with the IntelliBond source. Cows were subjected to three experimental periods: A baseline period in thermoneutral conditions, a heat stress period using electric heat blankets, and a recovery period in thermoneutral conditions.
4 TRIAL TAKEAWAYS
The study comparing the sulphate and IntelliBond Z sources revealed four key health and performance improvements among animals supplemented with IntelliBond:
1. Improved intestinal barrier function: During heat stress, cows supplemented with a IntelliBond Z showed a marked decrease in gastrointestinal permeability compared to cows in the control group (Figure 1). This improvement was particularly evident in the early stages of heat stress, suggesting that Selko® IntelliBond® Z helps maintain the integrity of the GIT barrier.
2. Reduced Inflammation: Heat stress typically triggers an inflammatory response, with increased levels of acute phase proteins (APP) such as haptoglobin (Hp). The study found that cows supplemented with the IntelliBond Z had a more controlled inflammatory response, with lower levels of Hp during heat stress recovery (Figure 2)
3. Enhanced metabolic health: The study also showed that supplementing cows with the IntelliBond Z mineral led to better metabolic outcomes. Compared to the control group, animals receiving the IntelliBond source had lower levels of nonesterified fatty acids (NEFA) and beta-hydroxybutyrate (BHB), indicating a less catabolic state and improved energy balance.1
4. Increased dry matter intake (DMI): During the recovery period, cows receiving IntelliBond Z showed a significant increase in DMI compared to the control group (Figure 3). This suggests that the IntelliBond Z helps cows regain their appetite and nutritional intake more effectively after heat stress.
APPLYING RESEARCH FINDINGS TO THE DAIRY SECTOR
These trial takeaways have profound implications for the dairy industry. By incorporating a more bioavailable source of zinc into the diets of dairy cows, farmers can mitigate the detrimental effects of heat stress, leading to improved cow health, increased milk production, and enhanced farm profitability.
1. Boosting milk production: Heat stress can reduce milk yield by up to 42%, as observed in the study. By maintaining intestinal integrity and reducing inflammation, feeding a more bioavailable Zn source helps cows sustain higher milk production levels even during periods of heat stress.
2. Enhancing animal welfare: Cow welfare is a top priority for dairy farmers. Feeding a less soluble mineral that is more available to the animal not only improves the health of cows during heat stress but also supports their recovery, ensuring they remain productive and healthy throughout the year.
3. Economic benefits: Economic losses associated with heat stress in the dairy industry are substantial. By reducing losses due to heat stress, feeding a more bioavailable trace mineral can help farmers save on veterinary costs, improve feed efficiency, and increase overall farm profitability.
CONCLUSION
The study by Rodriguez-Jimenez, et al. (2025) described above highlights how dietary changes in the ration can help support cows’ recovery from heat stress. By improving intestinal barrier function, reducing inflammation, enhancing metabolic health, and increasing dry matter intake, Selko® IntelliBond® Z brings a four-step solution to mitigate the adverse effects of heat stress on dairy cows.
As the dairy industry continues to face the challenges of climate change, heat stress is apt to be a growing concern for dairy farms. Feeding a trace mineral demonstrated to help support cows’ recovery is a practical step that is easy to implement on the farm.
1S. Rodriguez-Jimenez, E. J. Mayorga, M. A. Abeyta, B.M. Goetz, J. Opgenorth, S. K. Kvidera, M. M. McCarthy, K.E. Griswold and L.H. Baumgard, (2025). Evaluating the effects of zinc hydroxychloride on intestinal barrier permeability and biomarkers of inflammation and metabolism during and following heat stress. Journal of Dairy Science
About Gavin Boerboom
Having received his Bachelor’s in Biomedical Sciences and Master’s degree in Human Food sciences from Maastricht University in 2016, Gavin Boerboom joined Trouw Nutrition’s R&D department right after focussing on feed additives. In 2018 he combined this role in R&D with a PhD position at Wageningen University focussing on trace mineral nutrition in monogastric animals. He completed his PhD in 2021 and joined the Selko USA team afterwards focussing on providing technical support on trace minerals for the North American market. As of August 2022, he is part of the Global Selko Feed Additives team responsible for supporting trace mineral solutions in all animal species across the globe.
