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A cattle feed additive that is widely used by Cargill and other big U.S. beef producers was temporarily taken off the market Friday by its maker after a controversy over its effect on animal health.

New Jersey-based drugmaker Merck said it would temporarily halt sales of Zilmax in this country and Canada, just over a week after Tyson Foods said it would stop buying cattle that had ingested the additive. Zilmax is mixed into feed to bulk up cattle before slaughter, resulting in more meat for processors like Tyson and Cargill.

Arkansas-based Tyson told cattle feeders that a side effect of Zilmax might be causing animals to have difficulty walking.

However, Minnetonka-based Cargill and the few other giant U.S. beef producers have stood by Zilmax. Cargill says it has experienced no “animal well-being incident” that it could directly link to Zilmax.

Merck has maintained that Zilmax is safe for cattle and continued to do so Friday, but said in a news release it would temporarily suspend sales to “ensure effective implementation” of a previously announced scientific audit of the additive.

The company gave no indication when Zilmax would be back on the market.

Cargill said it supports Merck’s move. “We think it’s prudent,” Cargill spokesman Mike Martin said. “It’s always a good thing to conduct additional research when questions arise about a product like this.”

Cargill’s head of animal welfare will participate in a third-party group that Merck is establishing to oversee its Zilmax audit.

The additive’s animal welfare issues pose no food safety concerns for people.

Zilmax is mixed into cattle feed 20 to 40 days before slaughter, aimed at adding roughly 25 pounds of muscle to each animal.