STRAIGHT FROM THE HORSES MOUTH

Duane A. Lienemann
UNL Extension Educator

                              
     I had a question this week that I have to admit stumped me. A young person at the fair asked me what a “beta-agonist” was and I quite frankly had to say….”I am not sure, but I will find out.”  I decided I needed to do that this week-- and found it interesting enough to use for material in this week’s column. I had heard of “beta-blockers” for high blood pressure and I had heard of beta-carotenes which give the red, orange, and yellow color in vegetables. I remember seeing Beta Theta Pi fraternity at UNL in Lincoln. But this was a new one for me. I guess I should have figured that it had to do with a potential showmanship question considering the timing of the question. Let’s take a closer look at beta-agonists this week.
      I did find out I should have known what it was, as it is common in market animal production. The term “beta-adrenergic agonist” or “ß-agonist” is the descriptor of enhancement products, some of which livestock feeders add to rations for improved performance and carcass value. People in the show animal world are very much aware of these products with names like Optaflexx, Paylean and Zilmax. Now I feel rather embarrassed, as I could have given a pretty good description of those products, as a couple of them have been used for quite some time by the animal industry and particularly in the show animal world. I also learned that beta-agonists have been used in human medicine for a much longer time, as bronchial dilators for treatment of asthma. I wonder how they figured out that it could be effectively used in feed?
     There are two beta-agonists that I know of that are FDA approved for use in market beef in the United States - Optaflexx (ractopamine) and Zilmax (zilpaterol hydrochloride), and one for market swine - Paylean (ractopamine). There is another beta agonist, Clenbuterol, which is not approved for use in food animals in the U.S., and sometimes causes confusion about other beta-agonist products. Clenbuterol is approved for use as a bronchial dilator in horses (roaring horse disease), but is sometimes used illegally as a growth promotant in cattle in Asia and other parts of the world where they don’t have the restrictions like we have in the USA. The product stimulates dramatic muscle growth, and in parts of Asia is known as “lean-meat powder.”  So it is not a wonder that some people use it for enhancing their show animals.
     Unfortunately, Clenbuterol has gained notoriety here in the US because some shady individuals have used it in show animals, and it has been found in carcasses of animals at major livestock shows resulting in scandal, law-suits and the expulsions of exhibitors from future shows. The bad part is that Clenbuterol accumulates in animal tissues and residues in meat can be toxic to humans. I believe that it is especially dangerous to eat the liver of an animal that has been fed this additive. The good news is that this is a very small and isolated segment and we now test for the drug, and I firmly believe that Quality Assurance efforts in livestock associations and particularly in 4-H and FFA youth has had a very positive affect on helping educate producers on the use of these beta-agonists as they are meant – not illegally.
     The legal beta-agonists - Zilmax and Optaflexx for beef; and Paylean for swine; do not accumulate in animal tissues and have been shown through extensive testing to be safe at proper dosages used in meat animal production. In fact, scientists have shown that a human would need to consume 3.75 tons of Zilmax-fed beef to equal a single asthma-inhaler dose of a similar human medication – albuterol – for a four-year-old child. However; the European Union, China and Russia do not see it that way and ban most animals that has been fed beta-agonists.  Most likely their ban on products from animals fed beta-agonists is primarily a politically motivated non-tariff trade barrier intended to protect the country’s domestic pork industry. Russia has been a top customer for U.S. beef livers for example, but now most livers are going to Egypt at a reduced price. The EU, as most people know, also has banned the sale of carcasses from animals that were fed antibiotics, GMO’s and particularly hormones. So the use of these beta-agonists could have a global marketing aspect to it as well.
     While beta-agonists that are individually FDA approved for beef or swine, they are not approved for sheep and/or goats and would be off-label or illegal. Also using beta-agonists designed for one species on a different species --or altering amounts fed is also illegal. I would not be surprised however if some “cheaters” and/or those trying to find a show edge would use them for enhancements in animals that it is not approved for; use too much; or use too long. Zilmax, for instance, has been shown in research trials to increase rate of weight gain, improve feed efficiency, increase rib eye area, and increase red meat yield in cattle fed in confinement. You can assume that it would do the same on other species. The drug redirects energy utilization in the body to cause an increase in the amount of muscle or (lean protein) as compared to the amount of fat. So it should not be shock to see this drug used, both legally and illegally. I understand that Zilmax is a more potent than Optaflexx and is more expensive, but that doesn’t mean it couldn’t be found in show rations. If people want to cheat, they will find a way. This is one reason we have urine sampling and tissue tests on carcasses of animals at major shows! 
     It should be pointed out that these products do not help put fat on an animal and likely reduces fat on and in an animal. It has been shown that beta-agonists can actually cause an animal to grade a little lower and can have an effect on poor structural soundness by making the defect even worse. As competition increases at junior livestock shows, many exhibitors  many exhibitors look for ways to gain an “extra edge” in the show ring. While these products may help move an exhibitor towards the top of the class, they cannot take the place of good genetics, proper management, care and good honest herdsmanship!