April 9, 2014
Merck's attempt to test Zilmax on 240,000 cattle met with resistance
Cargill Inc and Tyson Foods Inc, two of the world's largest beef processors, which control 37% of the daily US beef processing capacity, stopped accepting cattle fed with the drug following reports it may cause lameness. Reuters reported in December 2013 that Tyson stopped taking Zilmax-fed livestock after more than two dozen animals that had been fed the drug arrived at one of its slaughterhouses with missing hooves.
The beef processors said their ban would remain until Merck had scientifically proven that Zilmax was safe for animals. They also want certainty that key export markets in Asia and elsewhere will accept such beef products.
With Zilmax off the market since last August, rival pharmaceutical firms have grabbed market share, with US feedlots switching to ractopamine-based Optaflexx, made by Merck rival, Eli Lily & Co.'s Elanco Animal Health unit.
The attempt to launch a large-scale study underscores Merck's determination to put the zilpaterol-based Zilmax, once the largest-selling growth drug for cattle, back on the lucrative agriculture drug market. Merck remains confident of the "safety and performance" of Zilmax and the US Food and Drug Administration has meanwhile deemed the drug safe for both animals and humans.
