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Beta agonists wrongly blamed for fatigued cattle syndrome

Beta agonists have no effect on problems seen in fed cattle at the packing plant.

Burt Rutherford

December 17, 2015

5 Min Read
Beta agonists wrongly blamed for fatigued cattle syndrome

According to research results recently published in the Journal of the American Veterinary Medical Association, the beta agonists zilpaterol and ractopamine have no effect on fatigued cattle syndrome.

That’s according to Dan Thomson, the Jones Professor of epidemiology and production medicine at the Kansas State University College of Veterinary Medicine. Thomson recently reported on the results of nearly three years of research into the issue, which first surfaced in the summer of 2013.

Back then, some fed cattle entering packing plants were having problems with being able to move normally and in some cases, the hoof wall was sloughing. At the time, beta agonists were implicated as a cause of the problem and summertime heat seemed to be a contributing factor. But what confounded veterinarians and cattle feeders alike was that cattle were normal when they left the feedyard, yet some showed clinical signs at the packing plant.

“But the one thing that was consistent was the inconsistency of whether or not a beta agonist was being used at the feedyard,” Thomson says. So researchers at the K-State College of Veterinary Medicine, Iowa State College of Veterinary Medicine and the Department of Animal Science at Texas Tech University began to dig deeper for the causes.

They looked back at research from 10 to 5 years ago on fatigued pig syndrome, a similar issue in swine where some pigs presented for slaughter had difficulty breathing, muscle tremors and other clinical symptoms. The research on pigs indicated that the animals that were at risk for problems were larger, heavily muscled pigs that had been handled aggressively at the production facility.

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So the researchers looked at the effects of beta agonists fed to cattle versus other potential causes. Among the many things they analyzed was blood chemistry. Analyzing the results of three different trials, the researchers found no difference in lactate levels in the blood between cattle fed a beta agonist and those that weren’t. Lactate is what makes your muscles sore after you exercise too much.

So researchers went back down the production chain to the feedyard, where they cooperated on some studies to see if they could create fatigued cattle syndrome in cattle that were not fed a beta agonist. The researchers set up a 400 meter course and moved some of the animals around the course at different speeds. Some were moved at a trot and others were kept at a walk.

“We had an increase in serum cortisol level when we ran the cattle through the trial, at 800 meters and 1,600 meters, and still had elevated levels an hour and two hours post-exercise by aggressively handling versus walking those cattle,” Thomson says. “And our lactate levels were through the roof, indicating that we can create fatigued cattle syndrome.”

More importantly, Thomson says the research revealed that cattle with a higher degree of finish responded more dramatically to aggressive handling that similar cattle that were kept at a walk. Keep in mind that these cattle were not fed a beta agonist.

“But the thing that’s most interesting to me is that the cattle that have lactate levels after we walked them 1,600 meters have the exact same lactate levels as they did before we walked them one step,” Thomson says. “They just don’t change when we take our time to handle these cattle correctly and take our time moving them to the loading facility. When we start to run these animals, when we start to move these animals in a more aggressive manner, is when we start to see the negative physiological reaction.”

And that reaction becomes more pronounced in bigger, heavier cattle, which has been the trend the past several years as feedyards attempt to squeeze every penny possible out of the cost equation. It also becomes more pronounced in the heat of summer.

Stewardship program

As a result of the research, Thomson says K-State is developing a fatigued cattle syndrome stewardship program. An integral part of the program is education, he says, and programs are under development with a launch set for April, 2016. “This is not going to be one size fits all,” he says. “We’re going to provide many different directions for feedyards and packing plants to work together and bridge that knowledge so we can prevent this syndrome in cattle.”

The education platform will look at many different aspects of cattle handling and help feedyard cowboys answer variety of questions, Thomson says. Among those questions: What are some of the things we can do at a feedyard to mitigate heat stress? How do we gather cattle in the home pen in a low-stress manner? What’s the best way to move cattle across the yard? When we’re weighing finished cattle, are we providing enough room on the scales? How long are cattle in the holding pen and do they have shade and water? What condition are the loading facilities?

Then there’s transportation. “We have the transportation Beef Quality Assurance program and we hope our transporters are getting that training so they understand how to move cattle,” Thomson says. In addition, the program will focus on the packing plant, looking at cattle comfort as the animals arrive at the plant and move into the facility.

Once the education component is in place, Thomson says they’ll work with packers to develop a monitoring, reporting and problem solving application to enhance information flow between feedyards and the packing plant.

 “We have a lot of different risk associations. But the biggest ones are the size of the cattle going out, the time of year and heat stress, and how we handle the cattle at the time of shipping,” he says. Thomson thinks the goal for the beef industry should be zero incidence of fatigued cattle syndrome. By focusing on the causes, that goal is within reach. 

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About the Author(s)

Burt Rutherford

Senior Editor, BEEF Magazine

Burt Rutherford is director of content and senior editor of BEEF. He has nearly 40 years’ experience communicating about the beef industry. A Colorado native and graduate of Colorado State University with a degree in agricultural journalism, he now works from his home base in Colorado. He worked as communications director for the North American Limousin Foundation and editor of the Western Livestock Journal before spending 21 years as communications director for the Texas Cattle Feeders Association. He works to keep BEEF readers informed of trends and production practices to bolster the bottom line.

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