For decades, factory farms have used antibiotics even in healthy animals to promote faster growth and prevent disease that could sicken livestock held in confined quarters.

The benefit: cheaper, more plentiful meat for consumers.

But a firestorm has erupted over a federal proposal recommending antibiotics only when animals are actually sick. Medical and public health experts in recent years said overuse and misuse of antibiotics posed a serious public health threat by creating new strains of bacteria that are difficult to treat – both in animals and humans.

“Over time, we have created some monster bugs,” said Russ Kremer, a Bonnots Mill, Mo., farmer who speaks nationally about the threat to the food supply.

“It is truly harmful to everyone to feed antibiotics to animals just for growth promotion and economic gain.”

The meat industry argues that the draft guidelines from the Food and Drug Administration are premature because a clear link has not been shown between antibiotics in livestock and health problems in humans.

“What FDA is doing, trying to restrict the use of antibiotics and require additional veterinary oversight, goes beyond where the science, their own science, has gone,” said Kelli Ludlum, congressional relations director for the American Farm Bureau.