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Sticky summer days create stressful time for livestock

Get proactive. Give your animals the tools they need to thrive during hot and humid weather.

Mindy Ward, Editor, Missouri Ruralist

June 1, 2023

3 Min Read
 cow drinking out of water trough
DRINK IT IN: The No. 1 requirement of any animal during a hot summer day is water. For example, beef cattle may need 2 gallons per 100 pounds of body weight per hour when temperatures reach 80 degrees F, according to the Journal of Animal Science. tap10/Getty Images

It’s not the heat; it’s the humidity. That is a true statement for livestock dealing with hot summer days.

Humidity plays a large role in whether an animal feels heat stress. Therefore, farmers need to use the temperature humidity index, or THI, to gauge whether the animal is in moderate, severe or extreme stress because of heat.

THI is like a safety gauge to monitor heat stress. It is calculated using air temperature and relative humidity.

In cattle, heat stress can occur when THI is above 80 degrees F, or if nighttime temperatures consistently remain above 70 degrees, according to University of Missouri research.

Specifically for sheep and goats, South Dakota State University research shows heat stress occurs when THI is 82 to 84 degrees F (moderate), 84 to 86 degrees F (severe), and at more than 86 degrees F levels (extreme).

While cattle, sheep and goats can regulate body temperature to some extent by sweating, pigs lack this ability. Much of the hog industry relies on housing with controlled temperatures and humidity. But for those raising pigs outdoors or for youth projects, heat stress is a concern.

Michigan State University research finds that pigs that weight less than 60 pounds can adapt to heat and humidity better than those 175 pounds or larger. A temperature of 83 degrees with humidity at 70% can create a dangerous situation for pigs.

Anyone raising livestock should monitor THI and know these signs of heat stress.

What to observe

Livestock owners should monitor animal behavior and look for these clues:

  • crowding around water tanks or shade

  • lethargy

  • poor appetite

  • increased respiratory rate

  • elevated rectal temperature

  • elevated heart rate

  • immobility or aimless wandering

  • staggering

  • drooling or slobbering

  • open mouth breathing

  • collapse

  • nonresponsiveness

  • seizures

  • death

But don’t wait for the signs of heat stress to appear, take precautions.

Reduce impact of heat, humidity

No matter the species, there are four common elements that every animal needs to help alleviate heat stress:

Water quality. Provide unlimited access to fresh and cool drinking water. Clean the tank often to keep algae and other parasites out. Keep in mind head space when in confinement operations. You do not want to overcrowd the water tank area.

Cool space. For animals in a pasture, provide shade. A shade cloth should be at least 8 feet off the ground for sufficient airflow. Orient shade either east-west or north-south. With an east-west positioning, the ground stays cooler but becomes muddy. North-south structures allow shade to move across the ground throughout the day. Or rotate animals to a pasture with natural shade such as trees or a lean-to.

If animals are in a barn, use ceiling vents and fans to circulate hot, humid air up and out of the barn. Also, consider sprinklers. However, do not use a mist as the water will not reach the skin for optimal cooling.

Animal handling. Livestock movement can create stress on the animal. During the summer months, work cattle, sheep or hogs in the early-morning or late-night hours. Avoid high heat times like 10 a.m. to 4 p.m.

Feed consumption. Animal body temperature increases after eating. Feeding at night or frequent, smaller portions can reduce instances of animals going off feed because of heat stress.

MU Extension beef specialist Eric Bailey stresses, if there one component from the list above to reduce heat stress, especially in cattle, it is water access. He says farmers should make plans to add extra tanks or get extra water to animals if the temperatures and humidity rise this summer.

About the Author(s)

Mindy Ward

Editor, Missouri Ruralist

Mindy resides on a small farm just outside of Holstein, Mo, about 80 miles southwest of St. Louis.

After graduating from the University of Missouri-Columbia with a bachelor’s degree in agricultural journalism, she worked briefly at a public relations firm in Kansas City. Her husband’s career led the couple north to Minnesota.

There, she reported on large-scale production of corn, soybeans, sugar beets, and dairy, as well as, biofuels for The Land. After 10 years, the couple returned to Missouri and she began covering agriculture in the Show-Me State.

“In all my 15 years of writing about agriculture, I have found some of the most progressive thinkers are farmers,” she says. “They are constantly searching for ways to do more with less, improve their land and leave their legacy to the next generation.”

Mindy and her husband, Stacy, together with their daughters, Elisa and Cassidy, operate Showtime Farms in southern Warren County. The family spends a great deal of time caring for and showing Dorset, Oxford and crossbred sheep.

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