WHILE Tyson's decision to suspend purchases of cattle fed zilpaterol hydrochloride (Zilmax, Merck Animal Health) garnered much attention last week, beef industry leaders and experts were discussing the role of beta-agonists in cattle feeding just prior to Tyson's potentially game-changing announcement.
Spearheaded by an industry working group formed earlier in the year, the beef checkoff convened a forum at the Cattle Industry Summer Conference that discussed issues ranging from the physiological effects of beta-agonists to animal welfare and consumer perceptions.
"We convened experts across the beef supply chain who have conducted extensive research on beta-agonists and engaged cattle feeding and animal health experts who have many years of experience using these products," National Cattlemen's Beef Assn. (NCBA) chief executive officer Forrest Roberts, co-moderator of the forum, said. "We will continue these efforts until we have solid answers to these questions."
Panelists featured leading animal scientists alongside cattle feeders and product experts who each discussed the use of beta-agonists, outlining the product category as another tool that helps producers produce more pounds of beef with the same or fewer resources than would be necessary absent the product's use. Using the products, however, comes with both intended and unintended consequences — or what one speaker referred to as "trade-offs."
Prior to the Tyson announcement, producer consensus pointed to a presumption that the benefits of feeding beta-agonists outweighed the possible unintended consequences.
Colorado State University animal scientist Daryl Tatum summed up those benefits simply: Beta-agonists increase muscle growth at the expense of fat and other tissues.
Describing a meta-analysis of published data showing the effects of ractopamine and zilpaterol on beef production and carcass traits, Tatum said studies have found that feeding beta-agonists can increase dressing percentage between 0.20% and 1.56%. That improvement is largely a function of an increase in carcass weight of 13.8-28.5 lb.
Additionally, studies have shown that the additive can increase rib-eye area by 0.29-1.08 sq. in. while decreasing fat thickness at the 12th rib by 0.01-0.03 in. Anecdotal evidence suggests the possibility of reduced marbling, although Tatum said the data don't necessarily support that presumption or the related assertion made in consumer media earlier in the year that "beef is losing its flavor."
Ultimately, Tatum said the biggest effect of feeding beta-agonists, from a practical sense, is reflected in data on saleable meat yield. According to the meta-analysis, trimmed subprimal weights increase between 4.9 lb. and 32.5 lb. when cattle are finished on the additive.
"To understand the value of the steer, you have to take it apart; the parts are worth different values," Tatum said. "Beta-agonists affect every segment in the beef supply chain in a positive way, from dressing percentage to carcass weight to subprimal yields. We've also seen some evidence that beta-agonists decrease weights of other components, including the hide, liver and kidneys, as well as the percent fat, trim and bone from the carcass."
Tatum did outline some potential concerns for the industry, however. The potential — and largely still unquantified — impact on consumer perceptions about beef, including safety, quality and product integrity, are significant areas of concern for beef marketers.
Any effects on product quality, including tenderness and marbling, could produce potentially long-term effects on beef demand. Use of the products certainly has posed some limitations on the opportunity to expand international markets, with countries such as Russia refusing to purchase meat from animals fed beta-agonists.
"We have to keep the main thing the main thing," Tatum said, quoting author Stephen Covey. "Right now, the main thing for the beef industry is demand."
Consumer demand for beef was one of a few areas of concern outlined by panelists at the forum, but animal welfare concerns were also brought to a head with Tyson's announcement.
The impetus for the forum was an industry working group formed by NCBA and the beef checkoff in April. NCBA senior vice president of research and innovation Bo Reagan told attendees that the group had already analyzed 54 peer-reviewed research trials and summarized the "knowns and unknowns" of beta-agonist use.
Among the unknowns were physiological issues in cattle, including reports of respiratory distress, particularly in hotter climates, behavioral changes such as handling challenges, hoof issues and slight increases in observed death loss.
Reagan noted that after the symposium, which was billed as the first major industry gathering of stakeholders on the issue, the working group will continue efforts to develop research trials that might answer some of the current unknowns, potentially leading to better management practices for beta-agonist use in finishing cattle.
With Tyson's announcement bringing a new sense of urgency to the discussion, the most salient comment of the day may have come from animal welfare expert Temple Grandin. When it comes to animal welfare issues related to beta-agonists, Grandin charged the industry with adopting a simple but direct mandate: "Fix it, or lose it."