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Tyson’s Zilmax decision stirs up cattle industry

by Wyoming Livestock Roundup

In a letter to their fed-cattle suppliers, Tyson announced on Aug. 7 that they would not accept cattle fed Zilmax, a beta agonist sold by Merck Animal Health, beginning Sept. 6.

“There have been recent instances of cattle delivered for processing that have difficulty walking or are unable to move,” the letter read. “We do not know the specific cause of these problems, but some animal health experts have suggested the use of the feed supplement Zilmax, also known as zilpaterol, is one possible cause. Our evaluation of these problems in ongoing, but as an interim measure, we plan to suspend our purchases of cattle that have been fed Zilmax.”

Tyson says the suspension will remain in effect until further notice. 

“This is not a food safety issue,” the letter continued. “It is about animal well-being and ensuring the proper treatment of the livestock we depend on to operate.” 

Industry response

In the wake of this announcement, Merck Animal Health released a statement stressing the importance of animal well being to the company.

“Zilmax has a 30-plus year history of research and development and rigorous testing,” Merck said. “Worldwide regulatory agencies have reviewed extensive data on Zilmax and have concluded that use of Zilmax according to the label is safe in cattle.”

“It is important to understand these data included rigorous animal health safety and well-being studies – conducted by university experts – that found the behavior and movement of cattle fed Zilmax is normal,” it added. 

On Aug. 16, Merck said that it would temporarily suspend the sale of Zilmax following concerns about the use of the product. The company says they remain confident in the safety of the product but will conduct an audit of how the product is used from the feed yard to the packing plant. 

The National Cattlemen’s Beef Association (NCBA) commended Merck Animal Health for taking steps to address the concerns of animal welfare. 

“America’s farmers and ranchers take animal care very seriously and support Merck’s efforts to ensure that Zilmax can be used responsibly to raise beef without compromising the health and well-being of cattle,” NCBA Chief Executive Officer Forrest Roberts said in a press release. 

“Our goal is to fully understand how the use of these products impacts animal welfare in real-life conditions,” Roberts continued. “If this process determines the current use of beta agonists is compromising animal welfare, we will take appropriate action to ensure that every animal raised for food receives the proper care it deserves.” 

Five-step plan

On Aug. 14, Merck Animal Health announced a five-step approach to ensure responsible beef plan to educate customers and interested groups who are involved in animal husbandry and well-being. 

The first step is re-certification of every feeder, nutritionist and veterinarian feeding Zilmax to cattle. 

“The re-certification process will begin immediately,” said a press release from Merck. “Special attention will be given to feed mixing and determining which cattle are good candidates for the use of beta agonists. We will engage third party experts to provide periodic reviews of certification.”

The second step includes Merck Animal Health reaching out to packers and suppliers to initiate a scientific audit focusing on the feeding on Zilmax. It will trace cattle from the feedlot to the packing plant to determine other potential causes of lameness and mobility issues. 

Based on the findings of this study, Merck Animal Health will take steps to reinforce appropriate management practices for feeder customers.

“Continuing in our work to advance animal well-being, we will form the Merck Animal Health Advisory Board within the next 30 days,” the company said. “It will be made up of representatives from small, medium and large feeders, packers, cow/calf operators, as well as animal health and nutrition experts, to review available data. If additional recommended management practices are needed, these will be identified, shared and promptly implemented.”

Merck says they are committed to sharing these findings and to being transparent throughout the process. 

Kelsey Tramp is the assistant editor of the Wyoming Livestock Roundup and can be reached at 

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