How it is calculated
The THI combines temperature and humidity into a single number, because high humidity makes it harder for the cow to shed heat. At 30 °C and 70% humidity, the THI is 81.
How to read the result
The cow is in her comfort zone.
Intake drops and milk starts to fall.
Sharp drop in production and a health risk.
These ranges are the usual reference for dairy cows. Zebu breeds and their crosses tolerate heat better.
Frequently asked questions
Where do I get the temperature and humidity?
From a weather station, a thermo-hygrometer in the barn or the weather forecast for your area.
What time of day should I measure?
At the hottest time of day, which is usually early afternoon. If the nights do not cool down, the cow does not recover either.
Which animals suffer most?
High-producing cows, freshly calved cows, and animals with dark coats or that are very fat.
Keep reading
This calculator is for information only and uses general references. Each farm's targets should be set with its veterinarian or technician.