But in the cattle industry, that isn't the only use of antibiotics. Since the 1950s, it's been common to give so-called "sub-therapeutic" doses to cattle throughout much of their lives, a regimen that can lead to an additional 3 percent to 5 percent weight gain.

That use of the drug has sparked some consumer concern. Susan Prolman, Washington, D.C., representative of the Union of Concerned Scientists' Food and Environment Program, said routine, non-therapeutic use of antibiotics is a threat to public health because it helps evolve a resistance to the drug.

That resistance would make the drug ineffective for treating illnesses. "We don't oppose therapeutic use, for a sick animal that's been diagnosed," she said of antibiotics. "Our concern is about routinely adding it to food and water, to gain weight faster."

Antibiotics are widely used in cattle, especially once they come to the crowded conditions of a feedlot, said Larry Hollis, a cattle veterinarian with Kansas State University Extension.

Source: The Hutchison News