Fatigued cattle syndrome can have a variety of causes

Since Merck’s beta-agonist Zilmax was pulled from the market in 2013, Kansas State University College of Veterinary Medicine Jones professor Dan Thomson, along with other university veterinarians, doctorate students and master’s students, has been researching whether or not the growth promotant causes fatigued cattle syndrome.

Wendy Sweeter

The research looked at the decreased mobility of cattle arriving at the packing plant. Thomson says packers were seeing cattle coming in during the summer that had difficulty moving, increased respiratory rates and muscle tremors.

After researching literature, they discovered the swine industry had an issue called fatigued pig syndrome. That syndrome was described at the packing plant during hot temperatures.

“It had been perceived to be associated with beta-agonists. The more we looked at it, the more it was associated with things such as large outweights, summer temperatures, improper cattle handling,” Thomson says.

Through a series of research projects, researchers looked at whether the syndrome was caused specifically by the beta-agonist. They found they could create fatigued cattle syndrome in cattle not exposed to the beta-agonist.

They also found that they could prevent fatigued cattle syndrome from occurring in cattle exposed to a beta-agonist.

Researchers concluded that the risk of using the beta-agonist was minimal to seeing fatigued cattle syndrome.

“The relative risk of the beta-agonist being used compared to improper handling or heat stress or larger outweights was pretty minimal,” Thomson says.

Thomson says the bigger issue was the timing of the launch of Zilmax and the increase in the use of the product correlated to heavier outweights. Packers and others worried that Zilmax was the reason behind fatigued cattle syndrome.

Thomson’s research found that multiple factors contribute to the syndrome, not simply feeding Zilmax or other beta-agonists.

“You can’t pick just one thing, and I think that’s our problem in a lot of things in animal health or human health. You sit there and go ‘What did I do wrong?’ or ‘What caused this?’” he says. “Well, there are some syndromes where there are 60 or 70 known ideologies to kick it off, and anything that’s going to cause stress in cattle has the potential of causing fatigued cattle syndrome.”

The research, funded by Merck Animal Health, the National Cattleman’s Beef Association and many state beef councils, showed that cattle on the beta-agonist and not stressed had no difference physiologically between them and cattle never exposed to a beta-agonist.

Thomson says feeders need to pay attention to how they handle cattle during hot temperatures. The difference in walking versus running a fat steer or heifer is night and day.

When they walked cattle a mile, their physiology did not change.

“They can walk forever, but as soon as you turn it up and tails are up, running down the alley, there’s two or three or four of them that just can’t handle it,” he says.

Beef producers should keep in mind that these cattle have been sitting in their home pen on a finishing ration and then have to move a long distance to get to the loadout area.

Thomson’s goal moving forward is to talk to producers about slowing down when they ship and understanding that it will take longer to ship cattle. Feedlots also need to think about either sorting cattle to be closer to the loadout area before loadout day or building multiple loadout areas within the feedyard.

He also says producers need to understand how to acclimate cattle to human interaction prior to the day of shipping. They also should avoid shipping at the hottest times of the day.

Communication between packers and feeders should improve to help work through problems either might be seeing, Thomson says.

To help feeders learn about fatigued cattle syndrome and proper handling, Kansas State University Research and Extension launched an online training module April 22. The module covers seven areas dealing with the syndrome.

“It covers the growth physiology of cattle. It talks about heat stress and exertion physiology in layman’s terms. Then it goes through what fatigued cattle syndrome is and then how to prevent it,” Thomson says.