The future of beta-agonists is still being determined

Other meat packers (like Cargill) soon followed, stating that “while Cargill has not linked Zilmax to any specific incidents involving animal well-being, the company does believe more research is necessary to answer recently raised questions regarding the use of this product.”

Tyanne J. Freeburg

Tyson quit purchasing Zilmax-fed cattle when they were concerned for the welfare of cattle and observed cattle that were severely lame at the slaughter plant. The company is worried about animals that are tender-footed and lethargic.

In response, Merck voluntarily pulled Zilmax (that created $159 million in sales in 2012) to further investigate the meat packers’ concerns.

It is important to note that this is only considered an animal welfare issue and not a food safety concern.

There are still different classifications and brands of beta-agonists on the market and allowed by Tyson and other meat packers in the U.S. Optaflexx is still available and has been used in place of Zilmax by feedlots since the ban.

Beta-agonists are not a hormonal product. Beta-agonists relax smooth muscle tissue in humans, and they are used in human medicine for asthma symptom control and in pregnant women to prevent premature births.

In animals, they are fed because they increase feed efficiency and the body produces more muscle rather than fat in the last days of the finishing period.

Dr. John Comerford with Penn State Extension states, “Beta-agonists are a class of non-hormonal compounds fed to cattle.

Their mode of action is to bind to receptors on fat cells in the animals’ body and redirect and reduce the metabolism of fat. Consequently, less fat is produced and less fat is stored in the carcass.

“At the same time, the compounds bind to receptors on muscle cells and redirect and increase the size of muscle fibers.

Muscle fiber size replaces some of the weight normally found from fat, and the total carcass contains a higher percentage of lean muscle.

These actions reduce the energy supplied by the feed to produce weight gain. With more weight produced by the same level of feed intake, feed efficiency is increased.”

According to “Beta-agonists: what are they and should I be concerned?” – a University of Nebraska Extension publication – “Market analysis reports indicate that the use of beta-agonists account for up to a 1.5 to 2 percent increase in meat production, which equates to approximately 24 to 33 additional pounds of beef and 6 to 7 additional pounds of pork.

If you estimate that half of the 24 million head of beef cattle harvested annually produce an additional 30 pounds of meat, this would be an additional 360 million pounds of lean beef a year.

This becomes a staggering number to ponder, especially as we continue to face drought, decreasing cattle inventory numbers and increasing grain prices, as well as increases in the price for red meat at a retail level.”

But is there a difference in meat quality when beta-agonists are used? Consumers were not often able to detect a difference from meat that was fed zilpaterol hydrochloride (Zilmax) and meat that was not.

If they did find a difference, “they still consider the beef acceptable, particularly for tenderness and overall palatability.”

It did reduce marbling scores and more animals were graded as select quality. According to Matt Doumitt, Ph.D., at the University of Idaho Meat Science Lab, consumers can expect a larger ribeye and minor effects on quality grade because it will decrease marbling and consumers may notice a slight decrease in tenderness.

The future of beta-agonists, specifically Zilmax, is still being determined. Merck is taking steps to initiate a scientific audit, a recertification of anyone that feeds the product, is forming an advisory board and will be sharing all their findings.

And though Zilmax may have an unknown future, it doesn’t look like other beta-agonist use is likely to decline in the near future.