Zilpaterol (zilpaterol hydrochloride; codenamed RU 42173) is a β2 adrenergic agonist. Under its trade name, Zilmax, it is used to increase the size of cattle and the efficiency of feeding them. Zilmax is produced by Intervet, a subsidiary of Merck & Co., and marketed as a “beef-improvement technology”.

Zilpaterol is a β2 adrenergic agonist with anabolic properties, which is Category A Prohibited Substance under the BHA Rules of Racing. It is used in the USA and some other countries as an animal-feed additive to promote weight gain, but such use is not permitted in the EU.

As far as the Food and Drug Administration is concerned, the drug, Zilmax, is legal to use. But large meat packers, which dominate the industry, have ostracized it after the drug was accused of making animals suffer. The drug’s manufacturer, Merck, has been working on a plan to rehabilitate it.

After temporarily halting Zilmax sales, Merck continues to state Zilmax is safe when used as directed, with no welfare concerns discovered in 30 research studies since the product was introduced in the United States in 2007.

Mix one (1) bucket (10 pounds) to 460 lbs of complete cattle feed, to provide 6.8 grams of Zilplatoral hydrochloride per ton, or add ½ pound (1 rounded cup) to 23 pounds of grain. Cattle should consume 60-90 mg per head per day. Each pound contains 160 mg of Zilpateral Hydrochloride.

Ractopamine is the active compound in several products (e.g., Paylean®, Engain®) administered in-feed to pigs and other livestock. These products increase muscle growth rate and improve feed efficiency while reducing fat deposition.

As of 2014, the use of ractopamine was banned in 160 countries, including the European Union, China and Russia, while 27 other countries, such as Japan, the United States, South Korea, and New Zealand have deemed meat from livestock fed ractopamine safe for human consumption.

Optaflexx is a beta-agonist that gives cattle feeders management options,+ allowing them to respond to changes in the market while optimizing both live and carcass performance.

If you buy industrially produced pork at a U.S. supermarket, it likely contains ractopamine—about 60 – 80 percent of industrial pork producers use the drug.

Blood and Urine Testing Ractopamine can be traced in the blood and urine for approximately 7 days. These tests will not determine use prior to 7 days after the withdrawal of the product.

Zilpaterol (zilpaterol hydrochloride; codenamed RU 42173) is a β2 adrenergic agonist. Under its trade name, Zilmax, it is used to increase the size of cattle and the efficiency of feeding them.

Zilpaterol. Zilpaterol (zilpaterol hydrochloride; codenamed RU 42173) is a β2 adrenergic agonist. Under its trade name, Zilmax, it is used to increase the size of cattle and the efficiency of feeding them. Zilmax is produced by Intervet, a subsidiary of Merck & Co., and marketed as a “beef-improvement technology”.

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. Zilpaterol has two chiral carbons and consequently four optical enantiomers.

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.