Late Summer Heat Wave Could Stress Livestock

August 22, 2014 11:49 AM
Late Summer Heat Wave Could Stress Livestock

Much of this summer has felt like early fall, but the summer heat is going to rally over the next several days, prompting concern about livestock heat stress.

"Air temperature and humidity can combine into a one-two punch that makes it hazardous for people and animals," said Matthew Dixon, meteorologist for the University of Kentucky College of Agriculture, Food and Environment. ". Dew point temperatures above 65 degrees lead officials to declare livestock heat stress emergency alerts."

Dixon said temperatures over the past seven weeks have been below normal, and the livestock heat stress index has stayed below dangerous and emergency categories. However, very hot and muggy conditions will overtake much of the state with temperatures in the upper 80s to mid-90s through the next week as an upper-level ridge of high pressure takes hold.

"In western parts of Kentucky, the heat will be more noticeable," Dixon said. "We expect highs out there to reach into the upper 90s with heat indices reaching upwards of 105 degrees. That will definitely push the livestock heat stress index into the emergency category."

The Livestock Heat Stress Index helps producers know when heat stress could create a problem for their animals. Periods of heat stress call for livestock producers to be vigilant in making sure their animals are able to withstand the conditions.

UKAg dairy specialist Jeffrey Bewley said the most important things producers can do are to provide cool, clean water and shade, with buildings as open as possible to help keep animals’ internal body temperature within normal limits. Sprinkler systems that periodically spray a cool mist on the animals also are beneficial.

"To keep cattle from becoming overheated, you certainly do not want to work them during heat stress conditions, including veterinary work, reproductive checks or vaccinations," Bewley said.

Producers should also avoid transporting livestock during a heat danger or emergency period. If they must move animals during this time, producers should try to do so with fewer animals per load. Planning trips so producers can load animals immediately before leaving and quickly unload upon arrival can help minimize the risk.

Regulation body temperature becomes difficult for all horses when temperatures exceed 90 degrees, so avoid exercising them during very hot periods. When humidity is high, temperatures much lower than 90 degrees can pose problems. Horse owners can reduce heat stress by scheduling activities during the cooler part of the day and giving horses plenty of water. Transporting horses during the cooler hours of the morning or evening can help. To reduce the risk of dehydration and heat stress, give horses access to water before, during and after transportation in hot weather.

Offer horses frequent drinks of water during work in hot weather. Allowing them to drink during work helps maintain water balance and relieves the urge to drink a lot of water after exercise. After a hard workout, water horses out gradually.

Even non-working horses will double their water intake during hot weather, so be sure plenty of water is available to horses in pastures, paddocks and stalls.

Lactating mares will have especially high water requirements, because they are using water for milk production and regulating body temperature.

Hot weather also will increase horses' need for salt, because salt is lost during sweating. Heavy rains can "melt" salt blocks in pastures, so salt licks should be checked.

Visit the UK Ag Weather Center website at to keep up with current weather, forecasts, heat stress indices and more.

Source: University of Kentucky Extension

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