Beta-Agonists, the Beef Industry and the Consumer

What's all the Ruckus about?

BY Dr. Stephen Blezinger | | Comments (0)

Over recent weeks, a new controversy has emerged in the beef cattle and beef production industry.  With the variety of issues already on the beef producer’s plate (no pun intended), another issue is not highly desired.  Recently, Tyson’s Foods took issue with the fact that some feedlots were feeding a product known as a beta-adrenergic agonist or beta agonist (β-agonist).  Their contention was that feeding of this product (Zilmax® by Merck) created structural problems in the animal, making it difficult to walk and move as it grew to larger weights.

When one approaches the typical consumer in the grocery store and begins to discuss beef products, it does not take long to determine two facts: 1) the typical consumer does not have a good grasp on the beef industry and what goes into the production of the beef products they purchase at the grocery store or a restaurant, and 2) the typical consumer has NO idea what a β-agonist is.  So with these two facts in mind, this article is geared more towards the consumer than the producer.

Beef Production and the Consumer

We live in a world where much of our consuming society is generations removed from the farm.  While a few folks can still look back to their parents or grandparents and the farms they came from, huge numbers of our population have no relation at all to agriculture and how food is grown.  Most of them have heard only the horror stories – how uncaring farmers are, how most foods are produced on “factory” farms where meat, milk and eggs are loaded with antibiotics and hormones and animals are routinely abused all in the name of corporate profits. This is unfortunate because it is so far from the truth.

While books can be (and have been) written on the truth and how these processes really work, the focus here is to address β-agonists, what they are and how they are used in the cattle feeding industry.  Finally, we’ll look into the nature of this most recent issue and how it affects the beef industry.

What are Beta Agonists?

Over the history of agriculture, a variety of products and practices have evolved that have helped the producer become more efficient and produce more food on fewer acres, at lower costs over shorter periods of time.  This is not only because of the demand for profits (assuming there are any), but we currently have about 6 BILLION people living on the earth with many living in areas where they cannot produce any of their own food.  The global population is growing, but the number of acres of farmland is not.  This means we have to produce more food on fewer acres.  We continue to live in a time where many people go hungry every day.  Increasing our ability to produce quality food is a critical responsibility.

In the United States and many other developed countries, there is a rising demand for healthier food options.  In many cases, this has resulted in a clamor for food with no antibiotics and no hormones.  But, in other situations, it is more basic than this.  It means food products that are higher in protein, lower in fat, and higher in minerals and vitamins.  Beef falls into the “lower fat category.”  Consumers have indicated they want a leaner product, with lower amounts of fat – especially the layer of subcutaneous fat that is found between the skin and muscle.

Enter the β-agonist.  Beta-agonists are compounds that, when fed to cattle later in the finishing period (the last 3 to 4 weeks prior to harvest), help create a physiological shift in how the animal’s body processes nutrients.  This shift causes a change (also known as repartitioning) in the animal from the production and deposition of fat tissue to the production and deposition of muscle (lean).  Deposition of lean in the animal is more efficient, so the end result is an animal that is leaner and also requires less feed to get to the end weight.  An additional result is the production of more lean beef.  Research has shown that feeding of the product results in a production increase of around 30 lbs. per head.  To put this into a real world perspective, if only ½ of the 24 million head of cattle fed annually in the United States are fed a β-agonist, this could result in a net increase in annual meat production of 360,000,000 lbs. of beef with no additional animals being fed.  This is significant in a time of high grain prices.  If a daily portion of beef were 8 oz., this additional meat production could help meet the protein requirements for almost 2 million people.

Beta-agonists have been used in human medicine for years.  For instance, the American Thoracic Society explains that β-agonists are medications that mainly affect the smooth muscles around the airways (bronchi and bronchioles).  When the lungs are irritated, bands of muscle around the airways tighten, making the airways narrower, resulting in breathlessness.  Beta-agonists work by telling the muscles in the airways to relax, widening the airways.  In many cases β-agonists can be used as an asthma treatment or in treating chronic obstructive pulmonary disease (COPD).  This is especially important for the treatment of very young children and older patients suffering from various respiratory related conditions.  http://www.thoracic.org/clinical/copd-guidelines/for-patients/what-kind-of-medications-are-there-for-copd/what-are-beta-agonists.php. [JB1]

In other applications, pregnant women in premature labor have β-agonists injected directly into their blood through IVs, to relax the smooth muscle of the uterus to prevent a premature birth. Thus, another example where β-agonists are life savers.

Then we make the leap from human medicine to livestock feeding.  We find here a completely different use for the compounds.  Beta-agonists have been in use in the cattle feeding industry since 2004.  They are not antibiotics or hormones as explained in this fact sheet from the University of Wisconsin: http://fyi.uwex.edu/youthlivestock/files/2010/11/Beta-Agonists-Factsheet.pdf.   Beta-agonists are medicated feed additives with specified withdrawal times.  The activity of the β-agonists occurs at the cellular level and does not affect the hormone status of the animal, thus it is not a steroid.  So, when fed to the animal over the last few weeks of the finishing period, the effects, as described above, become apparent.

There are two products that have FDA approval to be fed in this manner and for this purpose.  One of these is Zilmax® by Merck Animal Health. The active ingredient in this product is zilpaterol hydrochloride.  The second product is Optaflex®, available from Elanco Animal Health. This product contains ractopamine hydrochloride as the active ingredient.  This is the same compound that is in Paylean® (labeled only for use in swine).

Both products have been extensively researched and exhaustively reviewed by the Food and Drug Administration (FDA), and a complete set of product specifications and directions for use have been approved.

So What’s the Problem?

To begin, we live in a time and in a society where the consuming public is poorly informed when it comes to actual food production.  The media does not help this situation, as it is more concerned with exposure and interest generated by sensational and, in many if not most cases, highly inaccurate reporting.  This has resulted in consumers that are highly sensitive to any information indicating there could be a problem with a food source.

With regard to β-agonists, several points (in addition to the use in human medicine) need to be made.  First and foremost, these compounds have a very short half-life, meaning the animal’s organs break down, metabolize and excrete them very quickly.  They are not, for the most part, ever detected in meat sampled by the USDA. And when the rare positive does pop up, it is far below the Maximum Residue Limit (MRL) established for human safety by the FDA and by the international Codex Alimentarius Commission.  Thus the possibility of any type of residue is in meat of these compounds s very unlikely. http://www.thestockexchangenews.com/2013/08/13/expert-opinion-former-usda-food-safety-official-discusses-beta-agonists/[JB2]

With this said, along with the fact that it is common practice in medicine to give them in significant doses to our most vulnerable patients – including young children, pregnant women and their unborn babies – it is not a stretch to agree that it is safe to consume meat from animals supplemented with beta-agonists when it is largely undetectable.

So the issue is this:  as mentioned, Tyson’s Foods, who is a major beef processor and merchandiser, stated that they would no longer buy cattle that had been fed Zilmax®.  This has also been followed by similar actions by Cargill, Inc., the third largest meat producer in the United States, and most recently by the Chicago Mercantile Exchange who will no longer accept Zilmax-fed cattle in fulfillment of their contracts.  http://www.reuters.com/article/2013/09/23/markets-cattle-cme-idUSL2N0HJ29K20130923.   [JB3] In each case, the perception was that the cattle coming into their processing facilities that had been fed the product had structural problems and had difficulties walking and moving in general.  This is not a food safety issue.  The beef from these alleged affected animals is fine for consumption as is emphasized by the number of meat processors continuing to purchase these cattle.  If anything, this MIGHT be considered an animal welfare issue.  It is common knowledge that many companies have become exceedingly  sensitive to situations where they believe even a perception by the consuming public of a problem in animal welfare may have negative effects on their image in the market or might reduce their sales.  Another driving force may be misconceptions concerning the acceptance of β-agonist fed cattle in international markets.  While there are some restrictions in the European Union and in China as related to previous misuse of a different β-agonist (Clenbuterol) product, the restrictions have not impeded the United States from exporting beef and pork products to over 100 countries in 2012 alone.

Finally, while Merck is taking a responsible route to verify the potential existence of any of the problems Tyson’s expressed concerns over, there is no conclusive evidence that the use of β-agonists creates the types of joint and structural problems described despite a very large body of research that has been conducted on the feeding of these products to cattle and swine.


The use of β-agonist in cattle feeding programs has been shown to be a safe practice not only for the producer but for the consumer.  These products help us produce more beef (food) for a growing population.  They are commonly used in health treatments to the most vulnerable in our population and are rapidly broken down and excreted by the animal making residues highly unlikely.  Hopefully, the industry will quickly resolve the issues at hand and continue to work on strengthening consumer confidence in the beef product and industry.

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