Cargill Inc. said Thursday it “has no plans” to stop buying cattle fed with a growth enhancer that rival Tyson Foods Inc. (NYSE:TSN) claims has likely caused its livestock to have trouble walking.

Tyson, the largest U.S. meat processor, suspended purchases early Thursday of heifers raised on feed mixed with Zilmax, a drug that makes the animal grow large quickly. Merck & Co., Inc. (NYSE:MRK) denied that the drug could cause the cows’ wobbling.

But a spokesman for the privately held food giant told International Business Times that the company intends to keep buying Zilmax-fed bovine.

“The bulk of our cattle is purchased from outside feedlots, we don’t control our own,” Mike Martin, a Cargill spokesman, told IBTimes.

He noted that Zilmax, also known as zilpaterol, was approved by the U.S. Food and Drug Administration and has been in use for years.

“About 75 percent of beef cattle in the U.S. is fed these types of feed supplements,” he added. “Cargill has no plan to change current cattle procurement practices.”

Merck said in a statement that it was “surprised” by the letter Tyson sent to cattle feedlots around the country and insisted the mysterious cases of weak-legged cattle were not caused by its product.

“We are confident that, based on all of the available data on Zilmax, the experience reported by Tyson is not attributable to Zilmax,” the New Jersey-based company said in a statement emailed to IBTimes.