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Reducing heat stress on livestock is critical for upcoming summer months

by Wyoming Livestock Roundup

As summer approaches and temperatures rise, livestock are more susceptible to heat and humidity stress.

Heat and humidity stress have a negative impact on livestock. However, providing them with a cool and comfortable environment will improve production and performance during summer months. 

Heat stress

“Heat stress occurs when high ambient temperature and high relative humidity cause livestock to reach a point where they cannot cool their bodies adequately,” states Steve McNulty, U.S. Department of Agriculture (USDA) director.

According to the USDA Climate Hub website, Temperature Humidity Index (THI) incorporates both environmental temperature and humidity to determine an accurate representation of effective temperature. 

“By utilizing THI, farmers can monitor heat stress to determine if livestock are in moderate, severe or extreme stress because of heat,” says McNulty.

According to University of Missouri (MU) research, heat stress can occur in cattle when THI is over 80 degrees Fahrenheit or if nighttime temperatures remain around 70 degrees Fahrenheit. 

Likewise, heat stress will occur when THI is above 82 degrees Fahrenheit for sheep and goats, according to South Dakota State University research.  

Michigan State University (MSU) research concluded pigs under 60 pounds are more adaptable to heat and humidity than pigs over 175 pounds. However, it is perilous for all pigs when temperatures rise above 83 degrees Fahrenheit with 70 percent humidity.

An excellent resource available to producers is USDA’s SERCH LIGHTS alert. This helpful tool monitors daily forecasts and THI thresholds for cattle and will send an e-mail alert when heat stress conditions are possible for a specific location. 

To sign up for the SERCH LIGHTS alert, visit

Signs of heat stress

High day and night temperatures prevent livestock from cooling off, and they will begin to show visible signs of heat stress.

According to USDA, producers should monitor animal behavior by looking for noticeable signs. The first obvious sign of heat stress is open-mouth breathing or panting and slobbering. 

“As heat stress increases, livestock will decrease their food intake and become lethargic,” says MSU Beef Educator Kevin Gould. 

Producers need to take immediate action when the first signs of heat stress are detected, as early intervention is the key to survival. 

Eric Bailey, a beef specialist at MU, says, “Producers need to watch for signs of heat stress as they are often overlooked and result in cattle weight loss, poor breeding results and even worse – death.”

Bailey explains producers should watch their livestock breathe. 

“Cattle’s normal breathing rate is less than 90 breaths per minute, or a breath and a half per second. An animal that is breathing over 2.1 breaths per second, is an animal likely in an emergency heat stress event.”

Strategies for coping
with heat stress

Heat stress can be reduced by decreasing heat gain and improving the heat transfer rate. Basic heat management includes shade, air and water, as these three things are vital for for livestock survival. 

Protecting livestock from direct solar radiation aids in lowering their body temperature and respiration rate. 

In the May issue of the University of Nebraska-Lincoln’s (UNL) BeefWatch Newsletter, Dr. Rick Stowell, UNL associate professor and Extension specialist, discusses heat stress management. 

Stowell states, “Shade reduces both the direct solar heat load cattle experience and the indirect solar load. Cattle should have at least four to eight square feet of shade per head.”

The UNL Extension office advises allowing two to three inches of linear head space for water in a confined feeding operation. Bunk space for water is critical in preventing heat stress, as cattle will drink more than two gallons per 100 pounds of body weight during a heat stress event. 

Air circulation and air exchange are also critical components in reducing heat stress. Increasing air movement around livestock can be accomplished using fans, installing proper ventilation systems or with wind movement.

There is no question heat stress can impact livestock performance, so being prepared for warmer temperatures this summer can improve livestock well-being and keep them comfortable. 

Melissa Anderson is the editor of the Wyoming Livestock Roundup. Send comments on this article to

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