Merck (MRK -0.8%) defends Zilmax in light of its earlier decision to pull it off the market, saying it hasn't seen any safety or effectiveness issues beyond those observed in clinical trials before it was introduced in the United States in 2007.
"You will see lameness even in normal feedlots in animals that are not given beta agonists," says K.J. Varma, head of research for MRK's animal health unit. "Based on studies we've done, we don't see anything out of the ordinary in terms of lameness" associated with Zilmax.
The company has done 30 studies in 60,000 animals since Zilmax was introduced,
Separately, Brazil's JBS SA (JBSAY.PK) says it will continue to accept animals fed with Zilmax at its U.S. operations unless evidence emerges that the product is potentially harmful to their well-being, CEO Wesley Batista said in an interview.