Merck to study cattle industry use of Zilmax

In the wake of mounting questions over its popular growth feed additive for cattle, Merck’s animal health unit said it is launching a five-step plan to reach out to cattle packers and suppliers in the next 30 days to address questions concerns over Zilmax.

Among other steps, the New Jersey-based Merck Animal Health said it will launch a scientific audit of cattle feedlot operators and beef processors.

The audit will focus “on the feeding of Zilmax, and will follow those cattle from the feedyards to the packing plant to determine potential causes of lameness and other mobility issues during feeding, transportation, offloading and staging at the processing facility,” acccording to the company’s statement.

Merck’s statement didn’t cite the source of any such specific concerns, but Tyson Foods, the largest U.S. meat processor, said last week it will suspend purchases of cattle fed with Zilmax starting Sept. 6.

Tyson, in a letter to U.S. cattle feedlots, said it was worried about cases of cattle with difficulty walking although it did not know the specific cause of problem.

Zilmax, or zilpaterol, is a beta-agonist drug commonly used in the beef cattle industry to help animals gain additional muscle weight prior to slaughter. The drug is approved for use in Canada, where it’s marketed by Intervet.

Merck said it also plans to conduct a review of other potential compounding factors such as nutrition, transportation and receiving facilities that might affect animal health.

Merck did not state whether such audits will be voluntary or required from customers before Merck sells Zilmax to them.

The company said it’s committed to “re-certifying every feeder/nutritionist/veterinarian that feeds Zilmax to cattle” and added that the re-certification process would begin “immediately.”

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

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

– P.J. Huffstutter is an agriculture reporter for Reuters based in Chicago. Includes files from AGCanada.com Network staff.

Related stories:
Tyson to suspend buying cattle fed Zilmax, Aug. 8, 2013
Battle of the beta-agonists, March 23, 2012