UK Agricultural Meteorologist Warns of Livestock Heat Stress Dangers This Summer

By: Aimee Nielson

LEXINGTON, Ky. - It’s already hot outside, but University of Kentucky agricultural meteorologist Matthew Dixon said it’s about to get even hotter over the weekend (July 20-21, 2019), and livestock producers and horse owners need to do what they can to minimize animal stress.

“Much of the state is under an excessive heat warning,” Dixon said. “We expect highs to jump into the low to middle 90s each day. Some areas are hitting the upper 90s. Combined with elevated humidity, peak heat indices will run between 100 and 110 degrees. This heat will push the livestock heat stress index into the Danger to Emergency categories during the afternoon and evening hours.”

The combination of heat and humidity are a cause of concern for livestock health.

“The livestock heat stress index helps us determine what level of concern farmers and pet owners need to have for their animals,” said Dixon, who works with the Agricultural Weather Center in the UK College of Agriculture, Food and Environment. “That index helps producers know when heat stress could create a problem for their animals, so they can be even more vigilant in making sure they have to the necessary resources to combat the stress.”

“The most important thing producers and horse owners can do is provide cool, clean water and shade,” said Jeff Lehmkuhler, UK beef specialist. “It’s also a good idea to avoid working or transporting animals during periods of danger or emergency heat stress.”

Horses have difficulty regulating their body temperature when temperatures exceed 90 degrees. If humidity is high, the temperature doesn’t even have to reach 90 degrees to make life uncomfortable.

“Horse owners can reduce heat stress by scheduling activities during the cooler part of the day and making sure horses have plenty of water,” said Bob Coleman, UK equine extension specialist. “If you do transport horses during the cooler part of the day, give water before, during, and after transportation to reduce the risk of dehydration.”

Coleman added that even non-working horses will double their water intake during hot weather. Owners should allow them to drink often to help maintain water balance.

“If you let them drink often, it can relieve the horse’s urge to drink a lot of water after exercise, and they need to gradually drink after a workout,” he said. “Also remember, lactating mares have special water requirements, because they are using water for milk production as well as body temperature regulation.”

Hot weather also increases horses’ need for salt, because they lose the mineral during sweating.

It is important to keep buildings as open as possible to allow air to circulate. Fans can make a big difference, and sprinkler systems that periodically spray a cool mist on the animals are also beneficial.

Poultry are especially prone to heat stress. Mortality during extreme heat can be significant, and egg production and hatching rates can drop.

“Since the birds don’t have sweat glands to help get rid of excess body heat, they have to pant to cool down,” said Jacquie Jacob, UK poultry extension project manager. “It’s important to make sure chickens are in well-ventilated areas and they have access to clean, cool water at all times.”

Dixon said the good news is that relief is on the way.

“A strong cold front will push through the region Sunday night, July 21,” he said. “This will bring a much more comfortable air mass to Kentucky over the next work week.”

Editor’s Note: After a temporary cool spell, it will likely be back to high heat and humidity for the rest of July and August. The National Oceanic and Atmospheric Administration announced on Thursday July 18, 2019 that June 2019 was the Earth’s hottest June ever recorded. Overall, the planet was about 1.71 degrees warmer than an average June. June 2019 also marked the 414th consecutive month that the planet's temperature was warmer-than-average, NOAA said. That dates back to 1984. NOAA's report also said that so far 2019 was tied for the second warmest year on record, behind only 2016. There's a 100% chance that 2019 will be one of the five warmest years on record, NOAA said. Scientists say the record heat is what is expected from man-made climate change.
The UK Agricultural Weather Center provides statewide and county-specific weather information. View a specific location from the Kentucky map at

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