MERCK Animal Health announced Aug. 16 that it will temporarily suspend sales of its beta-agonist zilpaterol hydrochloride — marketed under the brand name Zilmax — in the U.S. and Canada.
Citing a commitment to helping producers use the product responsibly, the company announced earlier in the week a "five-step plan to responsible beef" that includes conducting a scientific audit and recertifying those who are authorized to feed the additive.
Its audit, undertaken in conjunction with third-party experts and a scientific advisory committee, will monitor the process of feeding of zilpaterol and will follow identified cattle from the feedyard to the packing plant to determine potential causes of lameness and other mobility issues during feeding, transportation, off-loading and staging at the processing facility.
Merck said suspending sales will provide sufficient time to establish valid study protocols, identify feeders and packers to participate in the audit and create a third-party team to oversee this process and validate results.
"We remain confident in the safety of the product, based on our own extensive research and that of regulators and academic institutions, and are committed to the well-being of the animals that receive it," said K.J. Varma, Merck senior vice president for global research and development.
Zilmax sales in the U.S. and Canada totaled $159 million in 2012. Industry estimates suggest that more than 70% of the fed cattle population in the U.S. is fed one of two approved beta-agonists: Merck's zilpaterol or Elanco's ractopamine (Optaflexx).
Following an Aug. 7 decision by Tyson Fresh Meats to no longer accept cattle fed zilpaterol in its cattle supply, Merck announced its five-step plan to address industry concerns about the product and also reiterated the scientific research behind the product.
Tyson's announcement set the market on edge, leaving the industry to ponder the potential implications of removing use of a popular growth promotant from an already tight cattle supply (Feedstuffs, Aug. 12).
While Tyson is currently the only major U.S. packer to stifle beta-agonist use in any fashion, market observers are waiting for the other shoe to drop.
Speculation as to Tyson's motives centered on the likely role of potential export business to countries such as Russia and China as more probable than Tyson's publicly stated concerns for animal welfare.
Merck said in an Aug. 13 statement that it has more than 30 years of research and development invested in zilpaterol, as well as rigorous testing, and is committing resources to "vigorously pursue all reported adverse events, whether or not they are deemed related to the product."
Merck emphasized, "We are confident in the totality of our data and the safety of the product and the well-being of the animals that receive it."
As part of its five-step approach, Merck committed to recertifying every feeder, nutritionist and veterinarian that feeds zilpaterol to cattle, effective immediately. The recertification will focus on feed mixing, as well as determining which cattle "are good candidates for the use of beta-agonists."
During an industry symposium on beta-agonists earlier this month, animal welfare expert Temple Grandin said recently reported problems of animals exhibiting symptoms of lameness at packing plants were not a result of deficiencies in plant design or operation but, rather, were due to feeding beta-agonists.
Fellow symposium panelist Mike Engler, chief executive officer of Cactus Feeders in Amarillo, Texas, countered that handling procedures at the packing facility were a likely factor in many of the symptoms observed and attributed to the feed additive.
In addition to its recertification plan and scientific audit, Merck said it would reinforce appropriate management practices for feeder customers "to include overall nutrition and feeding objectives, animal handling, low-stress environments and transportation."
While it is difficult to say, at this point, what might cause some of the mobility and respiratory issues highlighted by Tyson and others in recent weeks, sources privately speculated that off-label feeding practices are one possible culprit. Merck's recertification and focus on appropriate management could be an indication that experts within the company feel likewise.
Merck said the final two steps in its plan center on forming an Animal Health Advisory Board to review available data and recommend additional management practices, as needed. The company said it will share all of its findings and is committed to transparency.