Tool · Farmers
THI and summer plan for dairy cows
Heat stress from temperature and humidity, doses for the herd and a summer checklist.
Calculation tool
THI and summer plan for dairy cows
The THI (temperature-humidity index) combines temperature and relative humidity. Enter the values in your barn to see the heat stress band, the daily doses for the herd and the kilograms to prepare for the summer.
THI
Mild to moderate stress
Daily doses for the herd
- Alpha Unifeed Control
- kg/day
- Summer Stress Bovini
- kg/day
Summer plan: hot days
- Alpha Unifeed Control in total
- kg
- Summer Stress Bovini in total
- kg
THI 79.8: mild to moderate stress. For 100 cows: Alpha Unifeed Control 2–10 kg a day, Summer Stress Bovini 20 kg a day. For 30 days of heat: 60–300 kg of Alpha Unifeed Control and 600 kg of Summer Stress Bovini.
Heat stress bands
- No stress below 68
- Threshold of stress 68 to 71.9
- Mild to moderate stress 72 to 79.9
- Moderate to severe stress 80 to 89.9
- Severe stress 90 and above
Working bands: 68 from Zimbelman et al. 2009; 72, 80 and 90 from the Collier/Zimbelman table (University of Arizona). These are not Alpha data: to be validated with Alpha’s technical service. NRC formula (1971): THI = (1.8 × T + 32) − (0.55 − 0.0055 × RH) × (1.8 × T − 26), with T in °C and RH in %.
Checklist: how to manage heat stress
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Recommended doses
| Product | Dose |
|---|---|
| Alpha Unifeed Control | 20–100 g per head per day (targeted action on the mixed ration) |
| Summer Stress Bovini | 200 g per head per day (direct action on the animals) |
In hot weather intake can fall by up to 20%: estimate how much with the summer intake drop calculator.
This tool is also on the page Heat stress.
Transparency
How it works and sources
The THI is calculated with the NRC formula (1971) (1.8 × T + 32) − (0.55 − 0.0055 × RH) × (1.8 × T − 26) and compared with the working bands 68, 72, 80 and 90 (68 from Zimbelman et al. 2009; 72, 80 and 90 from the Collier/Zimbelman table, University of Arizona): these are not Alpha data, to be validated with Alpha’s technical service. The doses for the herd multiply the number of animals by 20–100 g of Alpha Unifeed Control and 200 g of Summer Stress Bovini a day; the summer plan then multiplies by the expected number of hot days. Checklist ticks stay on your device.
Data sources
- Alpha presentation “Stress da caldo” (Heat stress): consequences, five management actions, Alpha Unifeed Control 20–100 g/head/day, Summer Stress Bovini 200 g/head/day
- THI formula (NRC, 1971). Working bands: 68 from Zimbelman et al. 2009; 72, 80 and 90 from the Collier/Zimbelman table (University of Arizona). These are not Alpha data: to be validated with Alpha’s technical service
Your Technical Partner
Let’s talk about your numbers
Alpha’s technical service checks the ration and dosages against your own situation.