UPDATED: Texas Tech scientist raises concern of using beta-agonists

Challenge is drug aids efficiency but raises incidences of death in beef cattle.

Use of beta-agonists in cattle production has received considerable national attention, and now, Texas Tech University veterinary epidemiologist Guy Loneragan has found that although there are significant societal benefits to the practice, an increase in death loss of cattle raises questions about welfare implications of its use.

In a peer-reviewed article published March 12 in PLOS ONE, Loneragan, professor of food safety and public health in Texas Tech's College of Agricultural Sciences & Natural Resources, adds to this ongoing national dialogue.

"Beta-agonists improve the efficiency of beef production, and this improvement provides important societal benefits," Loneragan said.

"The beta-agonists approved by the U.S. Food & Drug Administration for use in cattle increase muscle growth and may reduce the amount of fat the cattle accumulate," he said. "This means cattle convert more of the feed it eats into beef, and it does this more efficiently."

The article is co-authored by Daniel Thomson and Morgan Scott of Kansas State University and is titled "Increased Mortality in Groups of Cattle Administered the B-adrenergic Agonists Ractopamine Hydrochloride & Zilpaterol Hydrochloride." The manuscript is freely available at: http://dx.plos.org/10.1371/journal.pone.0091177.

With the use of beta-agonists, cattle require less feed and less water to produce the same amount of beef than if no beta-agonists were used. Less land would be used to grow the crops used to feed the animals and, therefore, less fuel to produce the same amount of beef. The improvement in the efficiency of production has meaningful societal benefits, the announcement said.

"However, through our extensive analysis, we found that the incidence of death among cattle administered beta-agonists was 75-90% greater than cattle not administered the beta-agonists," Loneragan said. "This increase in death loss raises critical animal welfare questions. We believe an inclusive dialogue is needed to explore the use of animal drugs solely to improve performance, yet have no offsetting health benefits for the animals to which they are administered. This is particularly needed for those drugs that appear to adversely impact animal welfare, such as beta-agonists."

Even with this difference in mortality, the number of overall deaths reported in the paper was quite low and similar to industry average death losses, regardless of cause, according to Elanco Animal Health, which manufactures ractopamine.

Both Elanco and Merck Animal Health, manufacturer of zilpaterol, noted that their products have been evaluated and approved by the Food & Drug Administration and other regulatory authorities.

Elanco further pointed out that it has ongoing and continuous monitoring has been in place for the past decade to identify any potential adverse events to feeding ractopamine to cattle and any potential adverse events are reported to FDA and investigated appropriately.

Merck added that "only a well-designed clinical study, in a real world setting, coupled with analysis of data by third-party industry experts, can thoroughly confirm the safety profile and performance of a product." Merck explained that the new study was "based on observational information and we disagree with them. Using observational analyses where cattle are not randomized and where rigorous scientific procedures are not utilized, is not a respected scientific method to rigorously evaluate the safety and efficacy of any product."

"We certainly need to better understand the manner in which animals fed beta-agonist die at the feedlot and work out how to balance the societal benefits of beta-agonist use with societal expectations concerning the welfare of animals raised for food," Loneragan said.

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