From VOA Learning English, this is the Agriculture Report.
Regulators in the United States are asking companies that make antibiotic drugs to tell farmers to stop using some of the drugs on livestock. Antibiotics are medicines use to fight bacteria and infections.
Large animal farms around the world often use small amount of antibiotics to help healthy animals grow faster with less feed. They put the antibiotics in the food and water they give to cows, chickens and pigs.
Opponents of this use of antibiotic say it adds to worldwide resistance to such drugs. Public health experts say, using an antibiotic on an animal gives bacteria the chance to built double defense against the drug. This makes antibiotics less effective when they are used to fight diseases in humans.
Last month, the U.S. Food and Drug Administration asked drug companies to voluntarily change the words on the containers of antibiotics so far use in farm animals.
Michael Taylor is the agency's Deputy Commissioner.
"With these changes, there will be fewer approved uses, and the remaining uses will be under tighter control to minimize the impact on resistance," said Taylor.
The decision by the FDA to ask rather than order the drug companies to make the changes has angered some activists. But the FDA said, changes would be made more quickly if it ask the drug companies to voluntarily change how they use antibiotics.
Dimitri Drekonja is a doctor with the Infectious Diseases Society of America. He supports the FDA's decision to ask for voluntary changes, but he is not sure the drug companies will do what the agency has asked.
"If this voluntary effort is taken up by the entire industry and everybody goes along with it, then it will actually be a needed first and potentially last step. Will that happen? I have my doubts," Drekonja added.
Some large drug companies have already agreed to make the changes. Liz Wagstrom is the Chief Veterinarian at the National Pork Producers Council. He says the pig farming industry is preparing for a change in the way it uses antibiotics, even it will cost some farmers money.
"We may lose some efficiency. We may have some animals that may not grow quite as quickly or take more grain to reach their full weight, " said Wagstrom.
She also says the changes may mean farmers will have more sick animals.
Doctor Drekonja says it may be difficult to measure how the new policy affects drug resistances.
"It would be great if there was sort-of like a dashboard and you could watch the needle drop in the amount of antibiotics used and then watch the next gauge, which is the national resistance and see what happens there. We don't have two simple gauges like that," Drekonja says.
He says there is a lack of good information on the amounts of antibiotics used on farms, as well as by doctors.
Some bacteria have continued to be resistant to drugs for years even after they have been banned from animal use. But doctor say they have been taking more steps to limit their use of antibiotics with humans, and they believe farmers should do the same.