Zilpaterol Explained

Zilpaterol is a β2 adrenergic agonist.[1] [2] Under its brand name, Zilmax, it is used to increase the size of cattle and the efficiency of feeding them.[3] Zilmax is produced by Intervet, a subsidiary of Merck & Co.,[3] [4] and marketed as a "beef-improvement technology".[5] Zilpaterol is typically fed in the last three to six weeks of cattle's lives, with a brief period (three days in the US) before death for withdrawal, which allows the drug to mostly leave the animal's tissues.

Concerns have been raised on the impact of zilpaterol on flavor;[6] however, studies have confirmed that overall tenderness, juiciness, flavor intensity, and beef flavor remain within the normal variation observed in the beef industry and differences are smaller than what can be detected by the consumer.[7] In the meantime, several studies have shown the use of zilpaterol leads to increased size, feed efficiency, and value.[8] [9] [10] [11]

Merck reported Zilmax-fed cattle do not produce beef with a difference in taste or quality compared to cattle not fed the drug, but elsewhere, concerns have been raised about the beef's tenderness.[3] [4] Studies have variously found a slight reduction in tenderness,[9] an increase in shear force,[10] and a lower percentage of intramuscular fat (marbling).[12]

Prohibitions and processor adoption

As of October 2017, Zilmax was approved in 17 countries, notably the US, Canada, South Africa, South Korea, Ukraine and Brazil.[13]

As of 2013, Zilmax was banned in China, Taiwan, Russia, and many countries in the European Union.[14] [15]

In the US

Tyson Foods was the first among the largest U.S. meatpackers to adopt Zilmax. Because of concerns about tenderness and loss of marbling, Cargill and other meatpackers resisted the practice. The next adopters were JBS and National Beef, with Cargill finally joining them in mid-2012.[16]

On August 6, 2013, Tyson Foods banned Zilmax-fed cattle from its processing plants after cattle began arriving with missing hooves in large numbers during hot weather.[17]

Origin and formulation

Zilmax is produced by Merck in France, a country in which the substance is prohibited. As of October 2017, its commercial formulation was 4.8% zilpaterol hydrochloride, 8% polyoxyl castor oil, 4.3% polyvinyl pyrrolidone and 82.9% ground corn cob.[13]

Chemistry

Zilpaterol has two chiral carbons and consequently four optical enantiomers. These enantiomers are: (6R,7R)-, (6R,7S)-, (6S,7R)- and (6S,7S)-. RU 42173 corresponds to racemic trans-zilpaterol hydrochloride, a mixture of the (6R,7R)-(−)- and (6S,7S)-(+)-enantiomers.

External links

Notes and References

  1. Web site: Zilmax (zilpaterol hydrochloride 4.8%) Type A Medicated Article. Compendium of Veterinary Products — Merck Animal Health. Intervet/Merck Animal Health. 22 February 2016. 27 April 2017. https://web.archive.org/web/20170427084723/https://intervetus.naccvp.com/product/view/1047465?e=d97b22ed63e734e84c1a5910a9c8f531z1688. dead.
  2. Verhoeckx KC, Doornbos RP, Witkamp RF, van der Greef J, Rodenburg RJ . Beta-adrenergic receptor agonists induce the release of granulocyte chemotactic protein-2, oncostatin M, and vascular endothelial growth factor from macrophages . International Immunopharmacology . 6 . 1 . 1–7 . January 2006 . 16332507 . 10.1016/j.intimp.2005.05.013 .
  3. Web site: Petersen M . As Beef Cattle Become Behemoths, Who Are Animal Scientists Serving? . The Chronicle Review - The Chronicle of Higher Education . 15 April 2012 . Chronicle.com . 2012-04-16.
  4. Web site: Zilmax - Overview . Merck-animal-health-usa.com . 2012-04-16 . 2020-04-21 . https://web.archive.org/web/20200421000321/https://www.merck-animal-health-usa.com/products/zilmax/overview.aspx . dead .
  5. Web site: Zilmax® Post-Approval Research Nears Completion Intervet's New Performance Technology Offers Value throughout Beef Industry. Merck Animal Health USA. 29 July 2015. July 19, 2007. This is the first beef-improvement technology to add value all the way through the beef system.. 2015-09-26. https://web.archive.org/web/20150926055823/http://www.merck-animal-health-usa.com/news/2008-05-07_zilmax_post-approval_research_nears_completion.aspx. dead.
  6. Web site: Why Beef Is Becoming More Like Chicken . Slate.com . Feb 14, 2013.
  7. ZILMAX (Zilpaterol Hydrochloride): Type A Medicated Article for Cattle Fed in Confinement for Slaughter . Freedom of Information Summary, Original New Animal Drug Application, NADA 141-258 . Food and Drug Administration.
  8. Proceedings, Western Section, American Society of Animal Science . 50 . 1999 . Influence of the β-Agonist, Zilpaterol, on Growth Performance and Carcass Characteristics of Feedlot Steers . Plascencia A, Torrentera N, Zinn RA . 331–334 . 2012-04-16 . 2012-07-22 . https://web.archive.org/web/20120722040450/http://animalscience.ucdavis.edu/faculty/zinn/pdf/20.Pdf . dead .
  9. Montgomery JL, Krehbiel CR, Cranston JJ, Yates DA, Hutcheson JP, Nichols WT, Streeter MN, Bechtol DT, Johnson E, TerHune T, Montgomery TH . 6 . Dietary zilpaterol hydrochloride. I. Feedlot performance and carcass traits of steers and heifers . Journal of Animal Science . 87 . 4 . 1374–1383 . April 2009 . 19098247 . 10.2527/jas.2008-1162 . free .
  10. Delmore RJ, Hodgen JM, Johnson BJ . Perspectives on the application of zilpaterol hydrochloride in the United States beef industry . Journal of Animal Science . 88 . 8 . 2825–2828 . August 2010 . 20382871 . 10.2527/jas.2009-2473 .
  11. Lawrence TE, Gasch CA, Hutcheson JP, Hodgen JM . Zilpaterol improves feeding performance and fabrication yield of concentrate-finished cull cows . Journal of Animal Science . 89 . 7 . 2170–2175 . July 2011 . 21278106 . 10.2527/jas.2010-3422 . free .
  12. Holmer SF, Fernández-Dueñas DM, Scramlin SM, Souza CM, Boler DD, McKeith FK, Killefer J, Delmore RJ, Beckett JL, Lawrence TE, VanOverbeke DL, Hilton GG, Dikeman ME, Brooks JC, Zinn RA, Streeter MN, Hutcheson JP, Nichols WT, Allen DM, Yates DA . 6 . The effect of zilpaterol hydrochloride on meat quality of calf-fed Holstein steers . Journal of Animal Science . 87 . 11 . 3730–3738 . November 2009 . 19648490 . 10.2527/jas.2009-1838 . free . 2346/95089 . free .
  13. News: Le Bizec B . A General Perspective on the Use of Wada Prohibited Substances for Animal Husbandry . WADA . October 2017.
  14. Web site: Did Tyson Ban Doping Cows with Zilmax to Boost Foreign Sales?. NPR.org.
  15. News: Taiwan detects more U.S. beef with banned feed additive . Reuters . 29 October 2013 .
  16. Book: Leonard C . The meat racket : the secret takeover of America's food business. 2014. Simon & Schuster. New York. 9781451645811.
  17. Web site: Cattle Feet Were 'Basically Coming Apart' Before Merck Halted Sales of a Muscle-Building Drug. Business Insider.

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