(Adds Sen. Kennedy bill in paragraph 2)
WASHINGTON, March 17 (Reuters) - Despite growing public support to ban the nontherapeutic use of antibiotics in food animals, a U.S. representative said on Tuesday efforts to move legislation through Congress this year could be met with resistance.
The bill, introduced in the House of Representatives by Louise Slaughter and in the Senate by Edward Kennedy, would ban the use of antibiotics important to human health from being used on cattle, hogs, sheep and poultry unless animals are ill.
Drug manufacturers would be allowed to sell antibiotics for uses other than humans if they can show there is no danger to public health from microbes developing resistance to them.
"We're up against a pretty strong lobby. It will really come down to whether members of Congress want to protect their constituents or agribusiness," said Slaughter. "I do believe the chance are good, at least getting it through the House."
The bill has been introduced several times since the 1980s but has been blocked by agribusiness interests.
An estimated 70 percent of all antibiotics sold in the United States go toward healthy livestock, according to a study by the Union of Concerned Scientists.
Proponents of the ban say antibiotics are given to healthy animals over a long period of time to compensate for unsanitary and crowded conditions, and to promote weight gain, rather than to combat an illness.
The concern is that the overuse of antibiotics in animals leads to new strains of antibiotic-resistant bacteria. As a result, people may be at risk of becoming sick by handling, eating meat or coming in contact with animals that have an antibiotic-resistant disease.
Dave Warner, a spokesman with the National Pork Producers Council, defended his industry.
He said 95 percent of antibiotics given to pigs are for preventing, controlling or treating disease. If the bill goes into effect, Warner said piglet deaths would go up, producer costs would rise, meat output would drop and consumers would see prices climb.
"There is no question there is a rise in antibiotic resistant bacteria," said Warner. "What is in big doubt is that the use of antibiotics in livestock has anything to do with that."
Chipotle Mexican Grill Inc (CMG.N) has served millions of pounds of meat from animals raised humanely without antibiotics or added growth hormones as part of a broader company effort to serve higher quality meats and vegetables.
"This commitment has been good for business," said Steve Ells, founder and co-CEO of Chipotle, who said the company increases prices a small amount as it introduces higher quality products.
"It allows us to afford these better ingredients and customers have been willing to pay them," said Ells. (Reporting by Christopher Doering; Editing by Marguerita Choy)