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New app aims to help dairymen analyze heat stress levels

PD Editor Emily Caldwell Published on 27 June 2013


A new smartphone app is now available to help dairy producers be aware of the heat and humidity levels their cows are experiencing to better manage heat stress effects.



“What’s going on outside isn’t necessarily what the cows are experiencing in the barn,” says Elena Lindemann, marketing director for Purina Animal Nutrition, which developed the app.

“A producer can be standing in front of the cows wearing a T-shirt or light sweatshirt, feeling comfortable, while the cows are probably already heat stressed.”

The Cool Cow app provides a screen where users can slide bars for temperature and humidity in their area to determine their Temperature Humidity Index (THI).

This measurement is an indication of heat stress. The app displays heat stress level by colors:

  • Neutral: blue-green
  • Mild: light orange
  • Mild-moderate: orange
  • Moderate-severe: orange-red
  • Severe: red with orange tint
  • Extreme risk: red

Click here to view a video about the app.


“Cows begin to be heat stressed at the THI level of 68, which is when their milk production starts being affected,” Lindemann says. “And a THI level of 55 is enough to affect reproduction.”

According to the app, a temperature of 72ºF with 45 percent humidity is enough to reach a THI of 68.

The app features three other tabs besides the THI calculator. The first tab details the impact of heat stress, while the second tab provides information about how to prepare ahead of time for heat stress, symptoms to watch for and quick tips to combat heat stress. The last tab on the app provides information about Purina feed technologies.

The company is taking the app one step further by providing temperature and humidity sensors to producers at a discounted rate to install in their barns.

This allows dairymen to check the readings of the sensors, open up the app, use the calculator to move the sliders for temperature and humidity and then know the exact THI their cows are experiencing any given day or time of day.

“You can only manage what you can measure,” Lindemann says. “And this app is an important link in making the producer aware of the conditions their cows are experiencing.”


The app is available for iPhone and Android devices. PD


Emily Caldwell
Progressive Dairyman

How much will heat stress cost you this summer?

Heat stress is expensive. It is estimated that heat stress costs the dairy industry anywhere from $900 million to $5 billion each year depending upon the calculation used.

The level of stress experienced by an animal and resulting financial losses fluctuate as temperature and humidity go up and down.

“Regardless of which figure you use, money goes down the drain each year as a result of heat stress,” says Dr. Jamie Jarrett, dairy nutritionist with Purina Animal Nutrition LLC.

“But when we talk in numbers that big, sometimes it can be hard to relate that to what’s actually happening at the individual farm level.”

To help dairy producers understand what the impact heat stress is having on specific operations, Jarrett shares that heat stress can cause a farm to lose 10 to 35 percent of an animal’s current milk production.

A cow producing 100 pounds of milk in thermal neutral conditions could drop to 90 pounds of milk for a 10 percent loss or 65 pounds of milk for a 35 percent loss.

Consider if the milk price is $16 per hundredweight; the reduction to 90 pounds of milk equates to a loss of $1.60 per cow per day. The reduction to 65 pounds per day of milk equates to a loss of $5.60 per cow per day.

Take this example across a herd of 500 cows – they are looking at a loss of anywhere from $800 to $2,800 per day.

Knowing that heat stress does not typically happen for one day only, consider if a cow suffered heat stress for a period of 45 days; the losses for a 500-cow herd grow to $36,000 to $126,000.

If the herd is milking 1,000 cows, the losses become even more significant, ranging from $72,000 to $252,000. These numbers don’t take into account reproduction losses and extended days open.

“When we put financials behind these percentages, the losses an individual operation is facing start to become very real,” says Jarrett.

Jarrett reminds that at 72ºF most people are comfortable, but that is the breaking point for adverse effects depending upon the humidity level. “We need to change our mindset in how we think about heat stress.”

To combat the financial impact of heat stress, Jarrett advises that producers consider the following management strategies:

  • Invest in shade, fans and sprinklers for both the lactating herd and dry cows, most specifically close-up cows.

“Research shows the financial benefits of cooling both groups of cows,” she says.

  • Take steps to keep the holding pen cool. Research shows that cooling a cow’s body temperature by 3ºF resulted in an increase of 1.75 pounds of milk per cow per day.
  • Provide plenty of water.

“Cows drink more than you may think in warmer weather. Make sure water is not a limiting factor on your operation,” says Jarrett.

  • Choose a highly palatable energy source. Because intake levels are reduced, it’s very important to feed a concentrated source of energy that is very palatable and appealing to the cow.
  • Double-check your trace mineral and macromineral levels. The level of trace minerals and macrominerals in the diet may need to be elevated. Macrominerals can help cows cope with heat stress.
  • Keep an eye on potassium levels. During warm weather, cows lose potassium through sweat.
  • Raise dietary cation - anion difference or DCAD levels to account for warmer weather.

—From Purina Animal Nutrition news release