When dairy cows get too hot, they struggle to produce milk and stay healthy. Scientists reviewed research from the past 25 years to understand how tiny minerals—like selenium, zinc, and chromium—can help heat-stressed cows feel better. These special minerals work like shields in the cow’s body, protecting cells from damage and boosting their immune system. The review found that giving cows the right mix of these minerals can improve milk production, help them eat more, and keep them healthier during hot weather. However, the exact amounts needed and the best combinations are still being figured out.

The Quick Take

  • What they studied: How tiny minerals in cow feed help dairy cows handle extreme heat and stay productive
  • Who participated: This was a review of many studies done on dairy cows experiencing heat stress, published between 2000 and 2025
  • Key finding: Six key minerals—chromium, selenium, zinc, copper, cobalt, and combinations of these—appear to help heat-stressed cows produce more milk, eat better, and fight off illness more effectively
  • What it means for you: If you work with dairy cows or care about animal welfare, this suggests that adding specific minerals to feed during hot months could be a practical way to keep cows healthier and more productive. However, the right amounts still need more research.

The Research Details

Scientists searched through thousands of scientific papers published between 2000 and 2025 about dairy cows experiencing heat stress. They looked specifically for studies that tested different minerals and measured how well the cows performed. This type of study, called a ’narrative review,’ lets researchers gather information from many different experiments to see what patterns emerge.

The researchers focused on six specific minerals: chromium, selenium, zinc, copper, cobalt, and combinations of these. They examined how these minerals affected three main areas: how well the cow’s body defended itself against damage, how strong the cow’s immune system was, and how the cow’s body processed food and energy.

By comparing results across many studies, the scientists could identify which minerals seemed most helpful and which areas still needed more investigation.

This research approach matters because heat stress is a real problem for dairy farms, especially in hot climates or during summer months. When cows get too hot, they produce less milk, eat less food, and get sick more easily. Understanding which minerals help most can guide farmers on what to add to their cow feed to protect their animals and keep production steady. This is more practical than testing one mineral at a time.

This is a review of existing research rather than a new experiment, which means it summarizes what other scientists have already discovered. The researchers used well-known scientific databases to find studies, which is a good sign. However, because different studies used different amounts of minerals and measured different things, the results weren’t always consistent. The review authors themselves noted that more research is needed to figure out the best amounts and combinations.

What the Results Show

Chromium appears to be one of the most studied minerals for heat-stressed cows. When cows received chromium supplements, they tended to eat more food, produce more milk, and handle the heat better. This mineral seems to help the cow’s body use energy more efficiently, which is especially important when cows are stressed by heat.

Selenium, which works as part of special protective proteins in the body, helped cows fight off damage from heat stress and supported their immune system. However, studies showed mixed results when measuring milk production—some showed improvements while others didn’t.

Zinc helped protect cow cells from damage and reduced swelling in the body, but scientists weren’t sure if it directly improved milk production. Copper worked similarly, supporting the immune system and cell protection, though results varied depending on how much was given and the form it took.

Cobalt, which helps make vitamin B12, was linked to higher milk production and more fat in the milk. However, too much cobalt might actually hurt milk protein levels, showing that ‘more isn’t always better’ with minerals.

When farmers combined multiple minerals together instead of using just one, the results were often better than using minerals separately. Cows receiving multi-mineral supplements showed improvements in milk quality, udder health, immune function, and even reproductive performance during heat stress. This suggests that minerals work together in the body, and the combination might be more powerful than individual minerals alone.

This review builds on decades of research showing that heat stress harms dairy cow productivity. Previous studies identified that heat damages cells and weakens immunity, but this review specifically focuses on mineral solutions. The findings align with general nutrition science showing that minerals are essential for animal health, but this review highlights their specific importance during heat stress—a growing concern as climate change brings hotter summers to more regions.

The biggest limitation is that different studies tested different amounts of minerals, used different mineral sources, and measured different outcomes. This makes it hard to say exactly how much of each mineral works best. Some studies were done in controlled lab settings while others were on real farms, which can give different results. The review also noted that how well minerals work depends on the cow’s age, pregnancy status, and the specific environmental conditions, meaning one-size-fits-all recommendations aren’t possible yet. Finally, some minerals showed inconsistent results across studies, suggesting that more research is needed to understand why.

The Bottom Line

Based on moderate evidence: Consider adding a balanced mix of chromium, selenium, zinc, and copper to dairy cow feed during hot months. Chromium shows the strongest evidence for helping heat-stressed cows. Based on limited evidence: Cobalt may help milk production but should be carefully dosed to avoid too much. Work with a veterinarian or animal nutritionist to determine the right amounts for your specific situation, as optimal doses aren’t yet firmly established.

Dairy farmers in hot climates or those experiencing summer heat stress should pay attention to this research. Veterinarians and animal nutritionists advising dairy operations will find this helpful for making feeding recommendations. Animal welfare advocates interested in protecting cows from heat stress should know about this option. This research is less relevant for farmers in consistently cool climates or those raising beef cattle rather than dairy cows.

Improvements in milk production and heat tolerance may appear within 2-4 weeks of starting mineral supplementation, though some benefits like improved immune function might take 4-8 weeks to become noticeable. Long-term benefits for reproductive performance and overall herd health typically show up over months of consistent supplementation.

Want to Apply This Research?

  • Track daily milk production volume and quality (fat and protein percentages) during hot months, comparing weeks before and after adding mineral supplements. Also monitor feed intake amounts and cow body condition scores weekly.
  • If managing dairy cows: Work with your veterinarian to create a mineral supplementation plan for the hot season, starting 2-3 weeks before peak heat. Set phone reminders to ensure consistent daily supplementation. If interested in animal nutrition: Learn to read mineral content on feed labels and understand the difference between mineral sources (organic vs. inorganic forms).
  • Create a simple spreadsheet tracking milk production, feed intake, and visible signs of heat stress (panting, reduced activity) on a weekly basis during hot months. Compare data year-over-year to see if mineral supplementation improves outcomes. Also monitor veterinary records for illness frequency and reproductive success rates to measure long-term benefits.

This review summarizes scientific research on minerals for heat-stressed dairy cows but is not a substitute for professional veterinary or nutritional advice. Before making changes to your dairy cow feeding program, consult with a veterinarian or certified animal nutritionist who understands your specific herd, location, and conditions. Mineral supplementation should be tailored to individual farm needs, and excessive mineral intake can be harmful. This information is for educational purposes and should not replace professional guidance for animal health decisions.