Merck Plans Five-Step Review Process for Zilmax Additive

Claims of adverse effects on beef animal welfare and Tyson ban of beta-agonist push Merck to review product

Published on: Aug 14, 2013

Just days after beef processor Tyson announced the company would no longer accept animals fed the beta-agonist feed additive Zilmax, the product's manufacturer, Merck Animal Health, Tuesday released a plan to review and re-certify farms using the supplement to ensure its safety.

The product causes cattle to put on more muscle and less fat late in the feeding period.

"Worldwide regulatory agencies have reviewed extensive data on Zilmax and have concluded that use of Zilmax, according to the label, is safe in cattle," a Merck statement said.

Though Merck said that studies from University experts indicate that behavior and movement of cattle fed Zilmax is normal, riginal reports from Tyson indicated that the product was causing mobility issues, thus resulting in a call to end its use. The company listed a Sept. 6, 2013, date to end purchases of Zilmax-fed cattle.

Claims of adverse effects on beef animal welfare and Tyson ban of beta-agonist push Merck to review product
Claims of adverse effects on beef animal welfare and Tyson ban of beta-agonist push Merck to review product

In response to the deadline, Merck introduced a five-step approach to audit and recertify handlers and users of the product. Specifically, Merck said it will:

1. Re-certify every feeder/nutritionist/veterinarian that feeds Zilmax to cattle immediately. Special attention will be given to feed mixing and determining which cattle are good candidates for the use of beta-agonists;

2. Reach out to packers and suppliers to initiate a scientific audit, which will focus on the feeding of Zilmax, and will follow those cattle from the feedyard to the packing plant to determine potential causes of lameness and other mobility issues during feeding, transportation, offloading and staging at the processing facility. Merck will do a thorough review of potential compounding factors—such as nutrition, transportation, receiving facilities, etc., with the participation of third-party experts in the next 30 days;


3. Reinforce appropriate management practices for feeder customers to include overall nutrition and feeding objectives, animal handling, low-stress environments and transportation, based on audit findings;

4. Form the Merck Animal Health Advisory Board within the next 30 days, 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; and

5. Share findings and remain transparent about the review and audit process.

The National Cattlemen's Beef Association stood by Merck's claim that that the product is safe, noting that, "there is no scientific basis for saying the use of beta-agonists caused the animal welfare concerns cited by Tyson in their decision to stop buying cattle fed Zilmax. "

However, the group said it will also undertake a review of current scientific studies and real-life observations to supplement the work of Merck and explore any possible correlation between the use of beta-agonists and reported animal welfare issues.

"Our goal is to fully understand how the use of these products impacts animal welfare in real-life conditions. 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," NCBA said.

Tyson competitors Cargill and National Beef both have no plans to change suppliers' mandated production practices in regards to similar supplements.