High Temps, Humidity Bad for Livestock

OMAHA (DTN) -- Temperatures this week will be dangerous for animals. While some lower temperatures are on deck later this week, more high temperatures are again expected next week.

Livestock producers should implement different weather management strategies to keep their animals comfortable. High temperatures and high humidity levels are a bad combination for livestock, according to experts.

JUNE HEATWAVE

A ridge of high pressure in the upper atmosphere has built over the middle of the United States, according to DTN Ag Meteorologist John Baranick. The ridge promotes hot weather at the surface and is certainly leading to some extreme temperatures this week.

"Between the Rockies and the Appalachians, most of the areas are under some sort of heat advisory or warning," Baranick noted.

Temperatures in the Plains are likely to exceed 100 degrees Fahrenheit, while other areas of the Midwest and Delta will come close to that mark. With these high temperatures, combined with high humidity with dew points in the 60s or 70s, it is not good for animals being outside for long periods of the day, Baranick said.

Baranick said the good news is this June heat wave may be short-lived, but the bad news is the heat is set to return.

A system in the Northern Plains will push a cold front across the country this week, and temperatures are expected to fall back into the 80s F with lower humidity, Baranick said. It may take until Friday to clear Ohio, so the effect will be slow.

Another ridge of high pressure is expected to redevelop over the middle of the country Friday through the weekend, pumping temperatures and humidity back up again, and it will spread eastward.

Baranick said the saving grace is another cold front that will move through Northern areas again but Southern areas -- including the Central and Southern Plains, southern Midwest, Delta and Southeast -- will all be under some extreme temperatures.

"The ridge may even slide westward and bake the Southwest next week as well," he said.

WATCH LIVESTOCK IN HIGH TEMPS

High temperatures and rising levels of relative humidity is a bad combination for both feedlot and cow-calf operations, according to KSU Extension Veterinarian AJ Tarpoff. Cattle in feedlots can see higher levels of mortality, while cows in cow-calf operations tend to have issues with low levels of reproductively if heat stress is bad enough.

Tarpoff said cattle dissipate heat less efficiently than other animals. They will pant in an attempt to remove the heat through respiratory methods and will also sweat some but at only 10% of the rate at which humans sweat.

Several factors affect how cattle dissipate heat, including body condition score (bcs), weight, existing health issues, hair color and hair coat thickness.

"Some cattle still have their winter coats, which makes handling heat stress more difficult," Tarpoff said.

Cattle internal temperature peaks two hours after the peak of the environmental temperature, so even though the hottest part of the day is over, cattle could still be extremely hot. It takes at least six hours to dissipate the heat load on cattle, he said.

Tarpoff said day after day of hot conditions creates an accumulated heat load on cattle. This load is not able to be dissipated with just one overnight period.

MANAGEMENT CONSIDERATIONS

There are certain management practices that may limit the effects of heat stress on cattle. Tarpoff suggested cattle producers should have a plan in place to handle these conditions before the heat arrives.

Feeding cattle should be altered, for example. Tarpoff recommended reducing feeding activity during the hottest part of the day, specifically 70% of the daily feed offer could be delivered as late as possible in the afternoon.

Also, when it comes to handling cattle, never process cattle in the heat of the day; if you do have to work the cattle, try to finish this chore by 10 a.m., he said.

WORKING WITH HEAVIER CATTLE

South Dakota State University Extension Beef Feedlot Management Associate Warren Rusche wrote heavier cattle are more susceptible to heat stress. (See https://extension.sdstate.edu/….)

Fatigued cattle syndrome (FCS) is a condition that affects cattle mobility near the time of processing, he said. Cattle affected by FCS display an unwillingness to move or in severe cases can go down.

Rusche said feedlot staff should move these cattle slower; cattle walked to a load-out area were much less likely to develop FCS, compared to those that were handled at a trot. If possible, move these cattle to pens closer to the load-out area, which will minimize the distance the cattle need to travel on shipping day.

Rusche said feedlot operators will need to be aware of increased animal health concerns as higher temperatures arrive. Heavier cattle don't tolerate hot weather as well, especially if they have black hides.

USE SHADES, SPRINKLERS TO REDUCE STRESS

"Strategies such as shades or sprinklers can make a big difference in relieving heat stress conditions in feedlot cattle," Rusche wrote.

Tarpoff said sun shades and sprinklers can be useful if they are used correctly.

Sun shades should cover 20 square feet per head per pen. This is a considerable investment, so perhaps use it on the heaviest cattle or over sick pens, he said.

Sprinklers should be used to wet cattle, but not create mud in the pen, Tarpoff said. They should be used in early morning hours or overnight and shouldn't be run in the heat of the day, since that increases humidity in the pen environment.

Water availability should be watched closely during hot weather. Feedlot cattle should have 2 to 3 inches of trough space per head, he said.

"As the temperature goes from 70 degrees to 90 degrees, that animal will consume double the water consumption," he said.

HEAT STRESS TOOLS AVAILABLE

Tarpoff said cattle producers have many tools available to monitor conditions.

One of the most basic tools is the temperature and humidity index chart, which can be found in many different places. By knowing the temperature and humidity, producers can get a snapshot in time of current conditions and make pinpoint decisions from there, he said.

Another useful tool is the U.S. Meat Animal Research Center (USMARC) Forecast Maps. (See https://www.ars.usda.gov/….) This website consists of a seven-day forecast of cattle heat stress for the continental U.S., Tarpoff said.

For Kansas cattle producers, the Kansas Mesonet Animal Comfort Index (https://mesonet.k-state.edu/…) can give an up-to-the-minute update of heat stress across the state. A chart can be constructed to give even more details of heat stress in the last seven days, he said.

The University of Nebraska-Lincoln (UNL) Extension also wrote an article detailing practices cattle producers should consider to combat heat stress. (See https://beef.unl.edu/….)

There is also the DTN Cattle Stress Index. This tool, which calculates stressful weather conditions daily throughout the year, is part of the MyDTN package available to DTN subscribers. For a MyDTN trial subscription, go to https://www.dtn.com/….

Russ Quinn can be reached at Russ.Quinn@dtn.com

Follow him on Twitter @RussQuinnDTN

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