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Fatigued cattle syndrome: Are beta-agonists really to blame?

Progressive Cattleman Editor Cassidy Woolsey Published on 05 January 2016
beef cattle

Despite what critics have claimed, research has found fatigued cattle syndrome (FCS) to be a result of several factors, not just the use of beta-agonists, said Dr. Dan Thomson, a professor of production medicine and epidemiology at Kansas State University.

In a recent webinar, Thomson discussed the research conducted by him and his colleagues, as well as their valuable findings regarding FCS. In the presentation, Thomson concluded stressed cattle at the end of the feeding period can experience FCS, which can result in lame, lethargic and non-ambulatory cattle.

“Cattle that are fed beta-agonists are no more likely to develop FCS than other cattle, and there are no differences in this regard whether the cattle are fed zilpaterol, ractopamine or are not fed a beta-agonist at all,” Thomson said. “In reality, the factors that contribute most significantly to FCS are the finished weight of cattle, heat stress and animal handling practices.”

Leading up to the research, in 2013, packing plants reported mobility issues in cattle delivered to the facilities. As a result, Tyson Fresh Meats, the country’s second-largest beef processor, announced its decision to forgo further purchase of cattle fed zilpaterol due to animal well-being concerns – setting the stage for a much-needed study.

During their research, Thomson and his colleagues recognized that the symptoms of FCS were similar to the symptoms of swine affected by fatigued pig syndrome (FPS). During the late 1900s and early 2000s, the swine industry faced many of the same problems, such as reluctance to move, trouble breathing and muscle tremors. This was also during an era of increased carcass weights and the adoption of growth promoters, otherwise known as beta-agonists.

Referring to the study on FPS, Thomson said, “We had to continue to look for different answers, as people were first stating that it was a beta-agonist issue. So, then we determined that if it isn’t something that is occurring on the hog farm, but at the packing plant, the next thing to look at was handling techniques on their way to or at the slaughter facilities.”

As Thomson and his colleagues looked further into FPS, they found a study that took two different groups of hogs – one aggressively handled and the other low-stress handled. During this study, the two groups of hogs were looped over a 960-foot course. The aggressively handled group was run down the alleyway and probed with hot shots, while the low-stress group walked.

The next question was: Did the animals clinically show any signs of FPS at the plant or not? The results of the study showed that there were no indications of downer hogs in the low-stress handled group, while the aggressively handled group had downer hogs that exhibited symptoms of FPS and a significant increase in creatine phosphokinase levels when compared with the non-downer hogs.

“When we started to do our research on FCS and looking at what things could be causing the problems at the plant, this research is what kind of gave us the background to move forward,” Thomson explained.

The same study was then repeated in 2014 by Thomson and his colleagues, but with beef cattle. The cattle were also randomly assigned to two different handling treatments involving either low-stress handling or aggressive handling. The low-stress group of cattle was walked the distance of a mile with a lead rider to prevent the group from moving at a faster pace. The aggressively handled cattle, however, were moved along the alleyway at a speed equivalent to a seven- or 10-minute mile, similar to the speed cattle are moved through alleys in feedyards on a regular basis.

The researchers found increased blood lactate concentrations, heart rate and rectal temperatures, decreased pH levels, muscle tremors, reluctance to move and other common clinical signs in the aggressively handled group of cattle. They also found that heavier cattle responded more dramatically to aggressive handling when compared with those that walked.

With regard to the cause of stress, the study determined that factors such as heat load, animal size, cattle handling, time of day at shipping and animal transportation during the summer all led to cattle that were fatigued. In addition, factors such as time spent standing, available shade, water cooling, pen surface, cattle handling and density in pens can attribute to high amounts of stress as explained.

In response to this issue, Thomson and his colleagues are in the process of developing a prevention or “stewardship” program that will include educational modules, video trainings and handouts to assist feedlots, transporters and packing plants to effectively manage and identify FCS.

“The stewardship program will hopefully be a means to prevent this from happening at the packing plant,” Thomson said. “I am excited to move this stewardship program forward and to continue to serve the greatest industry in the world – the beef industry.”

For more information, the webinar recording will be available for one year and can be accessed through this link.  PD

PHOTO: Weight, heat stress and animal welfare are all contributing factors to fatigued cattle syndrome (FCS), according to a 2014 study, as opposed to previous concerns that beta-agonist use was the primary factor for FCS. Staff photo.