What we know about Fatigued Cattle Syndrome

Vet Advice with Dr. Ron Clarke

Fatigued Cattle Syndrome can exhibit in highly finished cattle following transport.

Fatigued Cattle Syndrome (FCS) appeared as a clinical syndrome during the summer of 2013. Scientists described it as a novel syndrome affecting highly finished cattle following transport. FCS became a welfare issue when first described and remains a potential welfare problem if not managed properly. Prevention of FCS appears on many conference agendas covering beef cattle welfare.

The appearance of FCS as a clinical entity coincided with the use of compounds called beta-agonists administered to cattle in finishing stages of feeding. Ractopamine is the beta-agonist most commonly associated with growth promotion in the livestock industry. Keeping food affordable for consumers is an industry priority. When ractopamine is used as a feed additive in the last 30 days of feedlot rations, hot carcass weight increases by 32 pounds. In addition, the red meat yields increase by 1.5 per cent or an additional 35 pounds per head.

Kendall Karr, director of nutrition services at Cactus Feeders, a multi-state, large, beef and pork production entity, puts it another way: cattle would have to gain an additional 81 pounds of live weight when not fed a beta-agonist. Losses in meat production for a company that feeds more than a million head of cattle each year are huge. According to Karr, “To put it in Cactus Feeders’ terms, it would mean we’d have to feed about 40,000 more cattle each year to maintain the carcass production — or about 60,000 more cattle to maintain the boneless meat production that we’d have gotten with a beta-agonist.”

Affected cattle exhibited various clinical signs including tachypnea (rapid breathing), lameness, and reluctance to move. Some cattle slough one or more hoof walls while in lairage pens or during transport. Cattle often recover when rested overnight. Serum lactate concentrations and creatine kinase activity, an indication of muscle damage, are often increased in affected animals. The clinical signs and serum biochemical abnormalities observed in affected cattle are similar to those observed in pigs with fatigued pig syndrome. Although anecdotal evidence generated concern that cattle fed beta-adrenergic receptor agonists were at greater risk of developing mobility problems, the scientific community accepts the fact that FCS is multifactorial.

Through the summer of 2013, abattoirs throughout the United States reported concerns about non-ambulatory, or slow and difficult to move cattle, and cattle that sloughed hoof walls. This resulted in the voluntary withdrawal of the beta-agonist Zilpaterol by Merck.

The company has worked tirelessly to develop strategies to better understand and prevent FCS and protect the welfare of cattle.

Ensuring appropriate animal welfare is a high priority for the beef industry, and poorly defined abnormalities in the mobility of cattle at abattoirs have gained considerable attention.

The mid-2000s saw the rise of ractopamine as a prominent growth-promoting agent for the meat industry. Three important facts about ractopamine are:

1. Ractopamine promotes lean muscle growth in the weeks prior to slaughter.

These drugs mimic the effects of adrenaline, resulting in increased protein synthesis in muscle tissue during the administration period. Ractopamine increases feed efficiency while producing a carcass with a higher lean muscle to fat ratio.

2. Regulations and guidance for the use of ractopamine varies among nations and the scientific community.

The International Codex Alimentarius Commission in conjunction with the Joint FAO/WHO Expert Committee on Food Additives (JECFA) published an information sheet in April 2012 summarizing their evaluation on ractopamine. Later that summer, Codex voted to adopt a maximum residue limit (MRL) of 10 ppb for ractopamine in pork and beef. Despite the long-awaited decision, many countries across the globe have either kept or moved forward with a ban on the controversial drug. All of the members of the European Union, along with China and Russia, have banned its use in domestic meat production as well as in imported products. Ractopamine use is currently legal in the U.S., Canada, and Mexico. The MRL in the U.S. is 50 ppb — well above the limit introduced by Codex.

3. Ractopamine’s effects on human health are not widely understood.

The effects of ractopamine on animals are fairly well documented, but scientists and government agencies continue to seek a better grasp on the potential health consequences of ractopamine in humans. It’s widely understood that ractopamine, when used according to appropriate veterinary practices, causes no harm to human health. This is also supported in the findings from Health Canada’s human safety assessment of ractopamine. They concluded that based on the assessment of available toxicological and residue data, the residues found in edible tissues of cattle, swine and turkeys resulting from the use of the ractopamine products (according to the label directions) are considered to be safe and would not pose any adverse health effects in humans. This conclusion further backs up the stance taken by Codex, which was made evident by its adoption of an MRL.

  • Factors requiring further direction include: Recognition that over-finished cattle are different, animal handling, heat stress, time of day at shipping, distance from pen to load-out, out weight/finish of cattle, pen weights/crushing, trucking and time of transport.

Handling finished cattle in the home feedlot is another piece in FCS prevention:

  • Gathering cattle in the home pen, moving cattle through the yard, pen weighing finished cattle, holding-pen management of finished cattle, and staging finished cattle close to shipping facilities.

Cattle handling and comfort at packing plants is another important factor. Consideration must be given to:

  • Time spent on truck waiting for the unloading dock, lairage and cattle comfort, shade and temperature control, water, cattle density in pens, pen surface management and time spent in lairage pen.

In conclusion: It’s critical to understand that larger cattle are different beasts. FCS is caused by multifactorial stressors, among them environmental temperature, size of cattle and handling.

About the author


Dr. Ron Clarke

Dr. Ron Clarke prepares this column on behalf of the Western Canadian Association of Bovine Practitioners. Suggestions for future articles can be sent to Canadian Cattlemen ([email protected]) or WCABP ([email protected]).



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