Some U.S. feedlots rue loss of 'Vitamin Z' Zilmax

THE SAFETY QUANDARY
Despite scattered reports of some distressed cattle from animal welfare experts, JBS USA and Tyson, Merck said it was not aware of any problems beyond those observed and taken into account when Zilmax won U.S. Food and Drug Administration approval in 2006.
The product makes up a tiny fraction of Merck's $47.3 billion in global sales. U.S. and Canada sales of Zilmax account for less than 5 percent of the $3.4 billion reaped by Merck's animal health business last year.
While markets such as China and the European Union have banned imports of meats raised with beta-agonists, in the United States, more than 70 percent of U.S. beef cattle that go to slaughter do so after consuming a regimen of beta-agonist drugs, according to industry estimates.
The FDA has deemed beta-agonists safe both for farm animals and human health, and there has not been a suggestion by regulators or industry that food safety is in question.
But the beef industry has learned the hard way that concerns about how our food is produced can mushroom quickly.

http://www.reuters.com/article/2013/08/18/us-livestock-tyson-zilmax-insight-idUSBRE97H0BI20130818