Merck prods cattle producers to help it test the safety of withdrawn Zilmax

Courtesy of Merck

The use of drugs in animal feed is already beleaguered by health advocates for the risk it poses to humans, as drug-infused meat continues to draw FDA ire. And even in the middle of this controversy, Merck ($MRK) wants to show that its cattle feed additive Zilmax--for fatter, beefier cows--is not dangerous, despite it having reportedly caused radical damage to bovines' ability to walk.

The Wall Street Journal said that the drugmaker plans to test Zilmax in about 250,000 cattle in a randomized, controlled study. But sources say beef producers like Cargill and JBS SA have pushed back against the move. While Merck planned to have the feed additive on the market by this summer, the study has been delayed.

Since Zilmax was pulled from the market last year, food producers have been looking to Elanco's Optaflexx to beef up their cattle--and while sales figures haven't been disclosed by its parent Eli Lily ($LLY), a spokeswoman tells the WSJ that buyers continue to see "strong interest" in the product.

And adding insult to injury for Zilmax, animal health industry leader Zoetis ($ZTS) is planning to get its growth-promoting drug for cattle on the market by the end of the year. The company got an approval of its ractopamine drug Actogain from the FDA last year.

Zilmax is also facing trouble on the global market. While South Korea is easing restrictions on importing beef fed with the additive, it has delayed those plans by at least a month. And China, Russia and the EU already ban it.

Zilmax was approved by the FDA in 2006 and has since been fed to about 25 million American cattle.

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