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Most dairy farmers don’t wake up thinking about temperature stress.
They think about mastitis, lameness, metabolic issues, high SCC, and cows that just aren’t performing the way they should.
What’s often overlooked is this:
Temperature stress is frequently the root cause behind many of these costly challenges.
Not just during heatwaves—but during everyday conditions when cows struggle to maintain a stable core body temperature.
When Cows Overheat, Everything Changes
When a cow’s core body temperature rises—even slightly—her priorities shift:
- She eats less (rumination creates internal heat)
- She stands more to try to cool herself
- She lies down less
- Her immune system weakens
- Her metabolism becomes less stable
These changes don’t always show up immediately. Instead, they quietly lead to:
- Higher somatic cell counts and more mastitis
- Increased fall lameness
- Metabolic disorders such as acidosis, ketosis, and milk fever
- Reduced milk production and reproductive efficiency
- Higher involuntary culling
By the time these issues are visible, cows have often been under temperature stress for weeks or months.
What the Research Tells Us:
Metabolic Health
According to OMAFRA (Ontario Ministry of Agriculture and Food), sub-acute ruminal acidosis (SARA) is a widespread issue in high-producing dairy herds. SARA reduces milk efficiency, compromises cow health, and increases involuntary culling.
Heat stress worsens this problem by reducing feed intake and disrupting rumen stability—particularly during early lactation when cows are already metabolically vulnerable.
Mastitis & Somatic Cell Counts
Research consistently shows that as temperature and humidity rise, so do:
- Environmental mastitis cases
- Somatic cell counts
Somatic cells often increase as a response to environmental stress. Once elevated, SCC can take weeks or even months to return to normal levels—even after temperatures drop.
Heat Stress and Cow Mortality
DHI (Dairy Herd Improvement) research in Ontario highlights the growing risk associated with heat events. As extreme weather events become more frequent and less predictable, dairy herds face increased mortality risk across farms of all sizes—not just during record-breaking heat, but during prolonged periods of stress.
Lameness Often Starts in Summer
University of Wisconsin veterinarian Dr. Nigel Cook has shown that heat stress plays a major role in cow behavior related to lameness.
When cows are hot:
- They stand to cool
- Resting time drops—sometimes by several hours per day
- Prolonged standing increases pressure on hooves
- Lameness often appears later, especially in the fall
Cooling at the feed bunk can provide short-term relief, but it also encourages more standing, which can unintentionally increase the risk of hoof problems.
Why Cooling the Stall Matters
A professional hoof trimmer summed it up well:
“The four hooves of a cow can’t handle extended standing on hard surfaces.
Hot weather often tips the scale toward lameness.”
If stalls are the coolest place in the barn, cows will choose to lie down.
That’s exactly where we want them—resting, ruminating, and producing.
The Core Cool Difference:
Cooling the Cow, Not Just the Air
Core Cool Systems was designed with one clear goal:
Maintain consistent cow core body temperature.
The system does this by:
- Delivering high-speed air directly over the stalls
- Using fine, precisely timed mist that evaporates instantly
- Automatically adjusting based on real-time Temperature-Humidity Index (THI)
- Responding to daily temperature changes—not just extreme heat events
By keeping cows within their thermal comfort zone, Core Cool Systems helps prevent temperature stress before it turns into health or performance problems.
All while using significantly less water and energy than many traditional cooling approaches.
What Farmers Are Seeing on Their Farms
Ontario Dairy Farmer – Near Ottawa
After installing a Core Cool System, this farm reported:
- Metabolic disorders such as acidosis and ketosis largely disappeared
- Late-pregnant and early-lactation cows became more consistent and healthier
- Somatic cell counts remained stable, with no wet stalls
- Fall lameness dropped from approximately 10% to 3%
“The changes weren’t instant, but over time they became very clear.
The cows are more comfortable, they perform better, and the operation is stronger because of it.”
The Takeaway
Temperature stress isn’t just a hot-day problem.
It’s a long-term herd health and profitability issue.
When cows stay core cool, the benefits compound:
- Better health
- Better performance
- Better longevity
- Better returns
With the right system in place, every day can feel like a cool day for your cows.
Want to Know What Temperature Stress Is Costing Your Herd?
A Core Cool Systems representative would be happy to talk with you about your operation and how temperature stress may be impacting cow health and your bottom line.
For number-driven producers, the Cost of Temperature Stress Calculator offers a deeper look at what heat stress could be costing your operation — often beyond what shows up on the hottest days.
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