🌡️ Heat Stress Index (THI)
Calculate your animals' stress level using temperature and humidity
What Does This Tool Do?
The Heat Stress Index (THI) calculator determines your animals' heat stress level from temperature and humidity values.
Provides milk yield loss estimates, stress category, and cooling recommendations. Enables daily monitoring and prevention during summer months.
In-Depth Guide
Read the science-based article on heat stress in dairy and beef cattle: THI thresholds, milk yield loss, and management.
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Frequently Asked Questions
THI (Temperature-Humidity Index) is an index that combines temperature and humidity to determine the heat stress level of animals. Milk yield loss begins above THI 72, and THI above 80 indicates severe stress. It is accepted as a standard metric worldwide.
At THI 72-80, daily milk yield may drop 10-25%. Above THI 80 (severe stress), 25-40% losses can occur. Reproductive performance also declines, feed intake decreases, and the immune system weakens.
Fans and misting systems, shade areas, cool water access, feed bunk cooling, night feeding programs, and ration adjustments (reduce fiber, increase energy density) are key measures. Cooling systems can lower THI by 5-10 points.
Take these calculations to the field
VetKriterFarm keeps your herd records, rations and reminders on your phone — animal by animal. All the calculators on this site are built in, and results are saved to the animal's record.
Free download · iPhone & iPad
