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It pays to keep cows cool

Tom Bailey Published on 07 April 2011

Trending topic article: Cow Comfort
Originally published: April 12, 2011.
Elanco Animal Health’s Tom Bailey urged producers to take a “45-day challenge” to get cow cooling equipment up and running properly. He said to repair and clean fans, sprinklers and drinking troughs and to adjust feed line soakers and control-box settings. or scroll down to read the article.

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We often hear, “We don’t have heat stress in this area of the country.” Yet recall the summers of 2009 and 2010. All across the Northeast, Midwest and upper Midwest, unusually warm weather had producers scrambling.

Feed intake, milk production, pregnancy rates and milk fat all declined. We saw more lame cows and more metabolic disorders in fresh cows. Heat stress can threaten health and performance and affect your bottom line.

Prepare now to meet the demands of heat stress. Take “the 45-day challenge.” Repair and clean fans, sprinklers and drinking troughs in existing systems. It typically takes 45 days to get all equipment up and running properly before heat stress begins.

Dust, dirt and grime on fan grills and blades can reduce airflow by 50 percent. Replace belts that are not in good working order. Check water supply lines for breaks from winter freezing.


Inspect sprinkler nozzles and clean for adequate water capacity. Adjust feed-line soakers and control-box settings so soaking frequency is adequate for environmental temperatures.

Evaporative cooling: Time, water and airflow
Setting the proper soaking cycle can be challenging. How long should I run the soakers? What is the time interval between soakings? At what temperature do I begin? Remember cows can begin to experience heat stress at just 72 degrees Fahrenheit.

Our suggestion: Get ahead of the heat stress challenge. Start before the temperature hits 72. Then as it gets warmer in the barn, soak cows more frequently. It takes time, water and airflow to reduce an animal’s body temperature once it experiences heat stress.

Studies show that when a cow’s temperature reaches 103 degrees, it takes 1 minute of water spray every 5 minutes, an airflow of 4-6 mph, and about 25 minutes of time before the animal’s temperature will begin to decline.

Exit-lane soakers alone, with a 5-second walk-through application, won’t reduce body temperatures. This inadequate approach may, in fact, exacerbate the problem. Exit-lane soakers should be combined with holding-pen cooling, feed-line soakers, barn fans and adequate drinking water. Time, water and airflow.

Feed-line soaking sprinklers
Sprinklers should wet the cow’s back and sides to the skin and then stop to allow the water to evaporate before another cycle begins. Evaporative cooling requires airflow of 4-6 mph and low-pressure, large-droplet water soakers. The soaking cycle depends on nozzle capacity and delivery rate, as well as environmental conditions.


  • Feed-line soaker nozzles generally deliver 0.5-to-1 gallon of water per minute (or about one-third gallon per cow per cycle).
  • Begin time: 70 degrees = 1-2 minutes ON time every 12-13 minutes (dependent on nozzle capacity) 85 degrees = 1-2 minutes ON time every 5-6 minutes (dependent on nozzle capacity)
  • As barn temperatures increase during the day, decrease the time between soakings. Some control boxes have a “smart” mode and will do this automatically.
  • Humid environments: Begin soaking at lower temperatures and soak more frequently.
  • Where fans are not positioned, soak more frequently.

Cool the holding pen
The holding pen is the most hostile place on the dairy, and there is not a dairy in this country that can’t benefit from holding pen cooling. Cows can generate 4,500-6,000 BTUs per hour (the heat from one cow can equal the amount of heat generated by a typical hair dryer).

When compacted in a holding pen, cows create a tremendous amount of heat. In heat audits, this is typically where the greatest increase in body temperatures can be demonstrated. Remember, reproductive efficiency declines when a cow’s temperature exceeds 102.2ºF. Cows can benefit greatly from holding pen cooling.

  • Holding-pen soaker nozzles usually deliver 1-8 gallons of water per minute (1 gallon per 160 square feet).
  • Begin time: 68 degrees = 1-2 minutes ON time every 6-7 minutes (dependent on nozzle capacity)
  • Make sure fans are generating airflow. Without airflow of 4-6 mph, the holding pen will become a “sauna” and heat stress is inevitable.

Drinking water
During heat stress periods, the most critical nutrient for cows to be able to access is water. Intake will double (up to 50-60 gallons per cow, per day) during summer months as cattle experience increased body temperatures.

Be sure to provide 2-3 linear feet of tank perimeter per 10-20 cows (3-4 inches per cow). This means accessible water space. Where waterers are aligned against a wall, count only the inches of accessible drinking space.

Provide a minimum of two water locations per group of cows. Check flow rates during times of high water use. Exit alleys should have enough water space for all cows in a parlor turn to drink. Refill capacity is imperative. Use a large pipe diameter to ensure no bottleneck occurs.

Studies indicate that where waterers are placed in exit alleys, this is where cows will consume as much as 30 percent of their daily intake. Consider adding troughs to holding pens. And always keep troughs clean.

Reduce heat stress and its effects
Heat stress has demonstrated negative effects on reproductive performance, productivity and health. But the following are good heat abatement strategies to help control this costly problem. Work with your adviser to identify the highest-priority needs and the right approaches on your dairy.

  • Evaporative cooling. Soaking at the proper interval and applying forced air at strategic locations is an effective way to cool cows. Key areas for soakers and fans: the feed line and the holding pen.
  • Customized systems. Modern evaporative cooling systems adjust soaking frequency and fan use based on environmental conditions. Use a system that will provide the right cooling for the prevailing weather.
  • Cooling at night. Often fans and soakers are turned off at night when heat stress seems to be less of a risk. Body temperatures in the herd may rise in this situation as humidity increases. Remember, humidity comes not only from the environment but also from water on the barn floor, urine and fecal matter and the cattle’s respiratory system. Cattle exhale a tremendous amount of water. Keep fans on at night when the temperature is above 68 degrees.
  • Abundant fresh water and feed. Access is key. The current recommendation for water space, for example, is 3-4 inches per cow. In a pen with 100 cows, that’s about 400 inches of accessible tank space, or more than 33 feet.
  • Split feedings. For higher intake during times of heat stress, feed more of the ration in the cooler evening times. Heat-stressed cattle need additional glucose. Research shows that during periods of heat stress, when dry matter intake declines, cattle do not mobilize fat for energy but shift glucose away from the mammary gland, affecting milk production.
  • Dry and pre-fresh cows. These animals often are not considered when designing heat abatement systems; however, research has shown they also need cooling and there can be substantial economic benefit. PD

Tom Bailey is a technical consultant with Elanco Animal Health. E-mail Tom at


Tom Bailey
Technical Consultant Elanco Animal Health