Beta Agonists and Cattle Feeding | Ask a Farmer

Feed ingredients in cattle diets vary between each and every farm and they are all used for a specific reason. This summer, a few questions have been raised about one particular feed ingredient, a beta agonist called zilpaterol. I want to share some educational links on the topic. We all have a choice of what feed ingredients to use and consume, and I respect that right for each and every person. The views are my own, and I only wish to add an informational voice to the conversation.

Earlier this month, Tyson Foods announced that as of September 6, Tyson will no longer purchase cattle that have been fed Zilmax, (zilpaterol), a beta-agonist by Merck Animal Health. According to a letter sent by Tyson to cattle feeders, the suspension will remain in effect until further notice. Tyson cited animal welfare concerns, including lameness, as reason for the change.

In response to the suspension, Merck Animal Health announced a Five Step Action Plan for how they are responding to the questions. The Action Plan includes certification and training efforts for cattle feeders using the Zilmax feed additive, a scientific audit to determine potential causes of lameness and mobility issues, reinforcing appropriate management practices for feeders, formation of an Animal Health Advisory Board, and being transparent with the findings from the event.

Merck Animal Health has since suspended sales of Zilmax until findings are evaluated and a definitive cause for claims of animal lameness are determined. Zilpaterol is one of two beta agonists used most commonly in finishing livestock. Ractopamine (marketed by Elanco Animal Health as Optaflexx for cattle and Paylean for swine) has not been the target of any animal welfare concerns.

What are Beta-Agonists?

Beta-agonists are FDA-approved animal feed ingredients that help cattle be more efficient in gains during the finish feeding period. When cattle are young, their nutrient intake is directed at building muscle, but as they age, they begin to put on more fat. Beta-agonists help cattle maintain their natural muscle-building ability, resulting in the leaner beef that consumers demand.

Cattle fed beta-agonists in the last few weeks prior to harvest, gain an estimated 30 more pounds of lean meat versus fat. This translates to an estimated 780 million pounds of additional beef from the same number of animals across the U.S. cattle feeders.

How are cattle feed additives used safely?

Extensive research shows that beta-agonists are metabolized quickly by cattle so they are not stored in the body and therefore are not present in the meat. Beta-agonists are approved for use in the United States, Canada, Australia and two dozen other countries across the developed world.

Nutritionists and veterinarians are consulted prior to the use of beta-agonists in the diet of cattle and determine if the use is necessary. There are several factors that guide this decision, including type of cattle, condition of cattle, customer expectations, such as yield and quality grades, as well as leanness, weather or seasonal conditions. Environmental goals of the operations are also considered because cattle fed these feed ingredients need less grain, which reduces the farm’s demand on natural resources.

Industry members and scientific researchers are continuing work to understand any possible correlation between the use of beta-agonists and reported animal welfare issues.

There are several academic, peer-reviewed research articles addressing the use of feed additives like beta agonists. Spend some time on Google Scholar to find more.

• Overview of the effects of beta-adrenergic receptor agonists on animal growth including mechanisms of action
• Effect of zilpaterol hydrochloride on feedlot performance, nutrient intake, and digestibility in hair-breed sheep
• Zilpaterol improves feeding performance and fabrication yield of concentrate-finished cull cows

Learn more about cattle feed additives

If you have questions about what feed additives are and how they are used in raising beef, feel free to ask me via the blog contact form. I have worked in several cattle feedlots that use many feed ingredients and can share my experience with you.

Not all cattle are fed beta-agonists, and when they are fed, it is only for a limited period of time. I respect any producers decision whether or not to use these feed additives, and the same respect goes for any choices consumers wish to make. I just wish to add some educated information to the conversation.

There are several online resources available that you can reference.