Where's the (Drug-Free) Beef?

Although the European Union banned the use of growth-promoting agents in cattle in 1989, some beef producers still treat animals with the drugs illegally. Now researchers have developed a sensitive technique to detect beef from cows given growth-promoting agents (J. Proteome Res., DOI: 10.1021/pr101255c).

Some beef producers treat cattle with drugs such as steroids, β₂-agonists, and corticosteroids to increase the animals' size. Scientists debate whether trace amounts of these growth-promoting drugs in beef can harm humans; indeed, in the U.S., some growth enhancers are legal and used widely. Therefore, European regulators must screen imported as well as domestically produced meat for the forbidden compounds.

Detecting growth promoters in meat isn't easy, says Giancarlo Biancotto, an analytical chemist at the Istituto Zooprofilattico Sperimentale delle Venezie in Legnaro, Italy, because "classical analytical techniques often aren't sensitive enough." But because the drugs trigger strong biological responses in animals, Biancotto and colleagues wondered whether they could indirectly detect growth-promoting agents in beef by measuring changes in protein expression.

To answer this question, the researchers fed cattle commonly used growth enhancers, alone or in combination. Then they used a technique called two-dimensional differential in-gel electrophoresis to compare the levels of hundreds of proteins in the skeletal muscle of treated and untreated animals. With the help of mass spectrometry, the team identified 29 proteins that are expressed at different levels in control and drug-treated animals.

The researchers now plan to examine the levels of these proteins in beef samples from slaughterhouses, some of which may be contaminated with growth-promoting agents. A subset of these proteins could eventually form the basis for a tool to detect illicit growth-promoting drugs, Biancotto says.