Cow

Weight-gain supplements gaining popularity for use in livestock cattle may be linked to serious health issues in cows, according to the Wall Street Journal.

The drugs, called beta-agonists, are marketed under brand names like Zilmax (Merck & Co.). Cows who have consumed the drugs are showing “unusual signs of stress,” reports the Wall Street Journal. “Some walked stiffly, while others had trouble moving or simply lay down, their tongues hanging from their mouths. A few even sat down in strange positions, looking more like dogs than cows.”

Merck & Co. announced that it would temporarily stop all sales of Zilmax as concerns from animal welfare advocates have risen over the feed additives. “I’ve seen cattle walking down a truck ramp tippy-toed,” Temple Grandin, a doctor of animal science and consultant to the livestock industry told the Wall Street Journal. “Normally, they just run down the truck ramp and jump out. We do not want to see bad become normal.”

Beta-agonists like Zilmax were originally developed for asthma relief in humans. But the drugs have found a booming market in the livestock sector. They’re mixed into cattle feed shortly before slaughter to boost weight through stimulating muscle gain instead of fat. Technically not a growth hormone, Zilmax (zilpaterol) “can add roughly 2%—or 24 to 33 pounds—to an animal’s final weight. Its rival, ractopamine-based Optaflexx, can add as much as 20 pounds,” reports the Wall Street Journal.  “Over 25 million cattle have been fed Zilmax since it was approved in the U.S.” said KJ Varma, senior vice president of research and development at Merck’s animal-health unit.

While Merck says all safety and efficacy procedures were followed in trials of Zilmax, the drug manufacturer is planning to perform a new round of studies with company-appointed researchers to design and conduct the studies. New research may not just be motivated by animal welfare concerns, but sales, reports the Journal. “Tyson Foods Inc….the largest U.S. meat processor by sales, told cattle suppliers it would suspend purchases of animals fed with Zilmax on account of ambulatory problems that the company observed, and suggestions by health experts that the drug might be the cause.”

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Image: lorenkerns