Cargill announced Monday that it would be the next meat packer in the U.S. to suspend purchases of cattle finished on the beta agonist Zilmax.

The ban goes into effect Sept. 30. The news follows Merck Animal Health’s Aug. 16 announcement that it would suspend sales of Zilmax in the U.S. and Canada, to conduct further research on its impact in livestock.

On Aug. 7, Tyson Foods announced it would not accept any cattle finished on Zilmax after Sept. 6.

“While Cargill has not linked Zilmax to any specific incidents involving animal well-being, the company does believe more research is necessary to answer recently raised questions regarding the use of this product,” Cargill said in a company statement.

“Consequently, Cargill supports Merck’s decision to suspend sales of Zilmax in the U.S. and Canada. The last of the cattle currently being fed Zilmax that are in Cargill’s supply chain will be harvested by the end of September. Cargill will be suspending purchase of Zilmax-fed cattle in North America, pending research being conducted by Merck. This will give producers adequate time to transition cattle currently being treated with Zilmax.”


Beta agonists are feed supplements used in the late stages of fed cattle growth to build lean muscle mass on the carcass. Zilmax, also known as zilpaterol, a class 2 beta agonist, is known as the more potent product in its ability to add weight and muscle. Optaflexx, or ractopamine, is a class 1 beta agonist made by Elanco Animal Health that also adds weight, but not as dramatically as Zilmax. Optaflexx has not been pulled off the market.

Tyson and Cargill are two of the largest meat packers in the U.S. The other two, JBS SA and National Beef, had not announced any beta agonist policy changes as of Monday.

What started on Aug. 7, with a Tyson Foods letter to cattle feeders announcing it would not accept cattle finished in Zilmax, has escalated into a blockbuster move that sidelined one of the key feeding ingredients for today’s cattle.

Although Merck said it stands by the science and safety of Zilmax, it said it would begin audits to determine its impact on animals, and reaffirm training procedures with producers, to assure its proper use.

According to a Tyson official, its move was not related to food safety, but animal welfare, after non-ambulatory and lame cattle were arriving at its facilities. Tyson said it couldn’t identify a specific cause, but said zilpaterol use had been suggested as a factor.

Cargill echoed that sentiment in its statement on Monday saying, “There are no food safety issues associated with Zilmax or this decision. Meat from cattle treated with Zilmax is safe to eat. Instead, this decision is linked to Cargill’s commitment to ensure the welfare of cattle harvested in the industry.”

The moves from Tyson, Merck and Cargill have unleashed a larger debate in the industry about beta agonist use, and whether its removal will affect the industry.

At the NCBA summer conference in Denver held earlier this month, it was a JBS USA video presentation showing lame cattle that raised additional questions of possible distress in beta agonist-fed cattle.

But beta agonists have been credited with producing more pounds of beef in spite of drought, high feed costs, and fewer head of cattle in the national herd.

“You can have some feeders at a real disadvantage,” said David Anderson, a livestock economist for Texas A&M University and Texas AgriLife Extension Service. “These are real powerful feed tools. They allow them to use feed efficiency, gain weight more efficiently, and it takes less feed.

“These products have been studied for decades. They have passed muster with all the international bodies that set standards for most countries in the world.”

But Anderson said uncertainty still exists in the eyes of consumers. He said beta agonist usage is similar to what happened with dairy producers years ago with the recombinant bovine somatotropin (RBST), which helped cows produce on average more milk per day.

Anderson called these “beneficial technologies that result in increased food production and lower prices for consumers.”

Scott Hurd, associate professor at the College of Veterinary Medicine at Iowa State University, and a former USDA deputy undersecretary for food safety, said the ongoing review of Zilmax could lead to amended procedures with its use and still protecting animal welfare.

“It’s easy to blame the products, and products would be part of equation. But if we can find other ways to solve the problem without throwing out the product, that’s much better.”

Those changes could include reducing dosage, changing the feeding, shortening the period of feeding, or starting the feeding and withdrawal 30 days earlier than currently required.

“Merck is working hard to help producers know how to use their product. There’s just a lot of mileage to go into how these products are used.”

Chris Reinhardt, a Kansas State University feedlot extension specialist, said the usage of products such as beta agonists may attract criticism from ag opponents. But federal regulation and oversight has made producers more vigilant in their compliance with regulated compounds, including beta agonists in feed.

“I really feel our cattle feeders do a tremendous job – not necessarily out of altruistic motives – monitoring and consistent application of all drugs. They have to. A violation of any of these rules is a big deal.

“So we’ve got the ability in our cattle feeding sector to maintain good records, checks and rechecks and balances in feed mill operations. I haven’t personally witnessed any intentional or non-intentional misuse of these two products.”

As for the impact pulling Zilmax will have on the beef supply, Anderson said the decision will have an impact on feeders’ bottom line, but it could possibly lower bids on feeder cattle going into the year. If the supply of beef drops, fed cattle prices could also go up as demand for finished product escalates.

Reinhardt said the fluctuation in the corn market – with supplies coming in higher this summer –will play a bigger role in the cattle prices than the reduced volume of beef. This will especially be the case if feeders using Zilmax move quickly to using the other beta agonist Optaflexx.

“I believe the difference in terms of volume – pounds of carcass weight sold – is going to be marginal,” Reinhardt said. end mark