WICHITA, Kan. (AP) -- Tyson Foods Inc. told cattle feeders this week it will no longer buy animals fed a supplement that's designed to bulk them up before slaughter, citing experts who suggest the drug may be causing cattle to become lame.
The decision by the food giant has raised concerns from industry experts that less beef will be available, which would drive up consumer prices. The growth-inducing drugs are approved by the U.S. Food and Drug Administration and help feedyards get roughly 25 more pounds of beef from each carcass. They've been increasingly used to offset dwindling cattle herd numbers, especially in the face of last year's drought.
"There have been recent instances of cattle delivered for processing that have difficulty walking or are unable to move," Tyson told feeders in a letter Wednesday. "We do not know the specific cause of these problems, but some animal health experts have suggested that the use of the feed supplement Zilmax, also known as zilpaterol, is one possible cause."
Tyson, one of the nation's largest beef processors, said the vast majority of the feedback the company has received has been supportive, because it's being done out of concern for animal welfare, company spokesman Gary Mickelson said Friday. He did not elaborate on the experts' findings.
In the Springdale, Ark.-based company's letter Wednesday, it said "This is not a food safety issue. It is about animal well-being and ensuring the proper treatment of livestock we depend on to operate." The purchases of Zilmax-fed cattle will end Sept. 6.
Zilmax manufacturer Merck Animal Health said in an emailed statement Friday that its product is safe for use in cattle. It said studies have found that cattle fed Zilmax have normal behavior and movement.
Merck, based in Summit, N.J., said it will work with Tyson to help identify other causes for the lameness.
"Again, we are confident that the totality of our data does not support Zilmax as being the cause of these experiences, and we remain confident in the safety of the product," Merck said.
Zilmax, one of two "beta-agonists" approved by the FDA, are mixed in with normal livestock feeds typically 20 days before slaughter. The additives work at a cellular level to more efficiently convert the feed's nutrients into lean muscle instead of fat.
Zilmax has been available in the United States for cattle since 2007, and until now, all four of the nation's big beef producers have bought cattle fattened on the feed additives. It's the more potent of the two approved supplements, and requires a three-day withdrawal period prior to slaughter.
"Our decision involves only the use of Zilmax in beef cattle," Mickelson said. "We've not had animal welfare-related issues with cattle given other supplements, but will take appropriate steps if we discover a reason for concern."
Tyson buys 26 percent of all cattle coming out of the nation's feedlots, CattleFax market analyst Duane Lenz said. He noted that the futures market rallied after the announcement, but faded when other packers didn't immediately follow suit.
"Obviously less production, less beef is bullish for prices," Lenz said. "What that will mean for prices will ultimately rest with how many of the packers do or do not go along with what Tyson did."
Should all major meatpackers stop buy Zilmax-fed cattle, retail and wholesale prices of beef would rise because there would be less beef available, Lenz said.
Cargill Beef was the last of the major meatpacking companies to accept Zilmax-fed cattle at its slaughterhouses, starting in June 2012, despite misgivings about the drug's potential negative impact on the quality of beef marbling and tenderness.
At that time, Cargill said had it not allowed Zilmax-fed cattle, it wouldn't have been able to buy enough of the animal to keep its plants running and meet customer commitments, noting that an estimated 70 to 75 percent of U.S. beef cattle are fed such growth promoters.
Cargill spokesman Mike Martin said Friday the company has no plans to change its cattle procurement process in the wake of Tyson's decision. Given the volume of cattle it processes, Cargill occasionally gets some that are lame, but it has not been able to link "anything scientifically" to the use of Zilmax, Martin said
Tyson said Friday it remains confident it will have sufficient supplies of cattle for its processing plants.
Steve Landgraf, manager of the Laikin Feed Yard in Kansas, said he stopped using Zilmax months ago after Tyson began paying feeders more money for cattle raised without the supplement.
"They have been trying to tell us they don't want it," Landgraf said. "Sometimes they try to tell you by the money and sometimes they tell you they just don't want it."
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