Merck pulls supplement over stress to cattle; Lilly demurs, citing similar drug's benefits

Weight-gain supplements called beta-agonists, used in the final weeks before slaughter to stimulate growth of lean muscle, have made cattle heavier but are believed to cause them unusual amounts of stress, including trouble walking or standing, Jesse Newman and Kelsey Gee report for The Wall Street Journal. Zilmax, which was designed to alleviate asthma in humans, can add 24 to 33 pounds, while Optaflexx can add as much as 20 pounds.

In response to concerns, Tyson Foods Inc. last week said it would stop buying Zilmax, and on Friday, Merck & Co., said it would suspend sales of the drug, Newman and Gee report. Zilmax and Optaflexx have been used in about 70 percent of U.S. cattle sold to slaughterhouses, according to Merck. Zilmax sales in the U.S. and Canada totaled $159 million in 2012. A spokesperson for Eli Lilly and Co., which produces Optaflexx, told the Journal that removing the drug would require producers to use an additional 91 bushels of corn a year, and would require 10 million more head of cattle to produce the same amount of meat without the drug.

Since the Food and Drug Administration approved the drugs in 2003 and 2006, the average weight of a steer at the time of slaughter has risen from 1,302 pounds in 2007 to 1,409 this year, Newman and Gee report. Gerald Timmerman, a third-generation cattle rancher and feeder whose family owns livestock operations in Nebraska and Colorado, told the Journal, as "grain prices accelerated, the margins got extremely squeezed in our business. That was the catalyst that drove demand for Zilmax up." (Read more)

UPDATE, Aug. 21: Some industry observers think Tyson is trying to increase its beef exports, but "others wonder of some cattlemen could have been giving cows too much of the drug," Agri-Pulse reports. (Agri-Pulse is subscription-only but offers a free trial.)