K-State vet shares tips for managing livestock through heat

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K-State vet shares tips for managing livestock through heat

20 July 2022

A veterinarian at Kansas State University is urging livestock producers to boost their plans to manage heat stress in their herds, a challenge that costs the US cattle industry up to $370 million in losses each year.

Cattle are resilient animals, said AJ Tarpoff, a beef veterinarian at K-State Research and Extension. They often adapt to high temperatures.

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But a buildup of factors – including humidity, solar radiation, skin color, diet, and more – can dramatically alter a cow’s ability to withstand the summer heat.

“It’s really a multi-layered challenge,” Tarpov said. “Every animal within a group or barn is not affected in the same way. Animals with higher scores in body condition, darker skins, or terminal calves and cows preparing for harvest are at greater risk of heat stress.”

Heat stress reduces the reproductive efficiency and performance of grazing livestock on pastures, Tarpov said. In confined facilities, heat stress often reduces livestock intake, which negatively affects their performance.

The human body cools itself on a hot day by sweating, which is called evaporative cooling. But Tarpov notes that cattle sweat only 10 percent as much as humans, and that panting is their primary method of dissipating heat.

“As temperatures rise and convection increases, they will start to breathe faster,” he said. “They dissipate heat through tiny droplets in the respiratory system.”

However, doing so makes the cows eat less, which puts them on a path of poor growth and future performance.

“It all has to do with convection,” Tarpov said. “Cattle’s internal temperature will peak two hours after the hottest day of the day. So, our strategy for keeping cows cool has to be built on knowing this.”

Another factor is that cattle produce heat by digesting food, usually 4-6 hours after eating. “If we feed the animals within the wrong amount of time, we can actually increase their heat load because the heat of digestion and heat from the environment build up on top of each other,” Tarpov said. “We want to prevent that from happening.”

Tarpov listed best management practices to help reduce heat stress in cows:

  • Cattle are received, shipped or transported only during the coldest periods of the day, preferably before 10 am
  • Adjust feeding times. Feed 70 percent of the animals’ rations as late in the evening as possible, which heats up their digestion overnight when temperatures are likely to be cooler. Reduce feeding during the day.
  • Heat management. Divide livestock between barns or reduce stocking density. Maximize airflow by removing obstructions around the facilities, including weeds. If possible, install shade structures, which can reduce solar radiation and reduce the temperature on the floor of the pen. Install sprinklers to moisten livestock at night or in the early morning so that the humidity does not increase.

Then there is of course the importance of saving water. Lots and lots of water.

“To put it in perspective, when the temperature rises from 70 degrees Fahrenheit to 90 degrees, livestock will consume twice as much water,” Tarpov said.

As a rule, he said, cattle should consume “about five times as much water as dry matter.”

“Cold, clean and readily available water is critical during heat stress events. We may have to increase the capacity of the water tank inside the pen to meet these needs with portable aquariums. Producers must be prepared for this.”

Tarpov said he follows two sources to help decide when to put a heat stress management plan into full effect.

The American Meat Animal Research Center (MARC) maintains a seven-day forecast tool for the United States, taking into account temperature, humidity, and solar radiation.

“The other tool I use is the Kansas Mesonet, which provides an indicator of animal comfort,” he said. The Kansas Mesonet, located at Kansas State University, is a network of watchtowers located throughout the state that updates weather information hourly.

“Right now, if we didn’t have nighttime cooling hours, the animal wouldn’t start every day in thermoneutral mode, so it’s most vulnerable on day two or three,” Tarpov said. Temperature, humidity, solar radiation – and most importantly now wind speed – play a role in the heat dissipation. Operations should start implementing strategies to control these stressors if they have not already done so.”

To watch a video on heat stress and livestock, click here

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