More on your meatless future right here: Reuters reports that Tyson Foods, which is the largest meat processor in the country, will next month stop buying and processing cows that have been fed the growth enhancer Zilmax (or Zilpaterol) out of concerns that the drug may somehow play a part in the animals’ basic health. In a letter to constituent feedlots, Tyson explained that, while the cause was unknown, it made the decision after being notified of "cases of cattle being delivered to its plants with difficulty walking or being unable to move."
Zilmax has been used by farmers around the world for nearly two decades, according to manufacturer Merck, but the FDA-approved supplement became available to domestic cattle producers in 2007 and has only recently become a prevalent force in the cattle industry.
Because the drug increases the size of cows over short periods of time, removing it from the supply chain will presumably lead to the production of less hefty specimens, and more expensive beef in the near future. In its letter to U.S. feedlots, Tyson, which processes approximately 6.7 million cows a year, did not single out Zilmax as the cause of the reported health issues within the farmed cattle population. "Merck Animal Health is confident in the extensive research and data behind the product and the fact that its safety has been well demonstrated," it wrote, Reuters reports. Meanwhile, Merck released a statement saying that tests have demonstrated the safety of Zilmax — it just "consistently delivers from 24 to 33 pounds of additional carcass weight."
Much in the same way the lab-grown burger faltered, however, critics say beef produced from cows raised on Zilmax-spiked feed tends to be blander. This is due to its effects as a “repartitioning agent” in cattle, Slate reported earlier this year. The growth factor leads to the production of more muscle but much less of the "fatty marbling that adds juiciness and flavor." In other words, the resulting meat contains less of the stuff that makes beef taste like beef. Despite this, Slate noted, by the end of 2012, four major producers with a combined 85 percent share of the domestic market were buying cows that had been fed Zilmax. Meanwhile, a 2012 study in the Chronicle of Higher Education pointed out that a number of scientists and research groups studying and ultimately responsible for reporting on the drug’s effects were subsidized with grants from Intervet, a Merck subsidiary.