Using probiotics as an alternative to antibiotics in poultry production has proven to be effective in keeping chickens healthy, according to Dr. Bruce Stewart-Brown, senior vice president of food safety, quality and live operations at Perdue Farms.

While the company still uses antibiotics in some flocks to control parasites and treat illnesses, it has reduced its use of antibiotics. Perdue Foods has removed all antibiotics from its chicken hatcheries. The company also stopped using antibiotics for growth-promotion purposes and offers no-antibiotics-ever brands Coleman Natural and Harvestland. To replace antibiotics, the company has looked at probiotics.

"As we took antibiotics out of the feed, we put some other things in, such as probiotics," Stewart-Brown told North Carolina Public Radio. "We've increased the amount of probiotics by five times over the past five years. It's a significant part of our program."

Probiotics, a form of bacteria, can crowd out harmful microbes that cause a chicken to be sick.

Stewart-Brown admitted he was once skeptical about the use of probiotics. While probiotics are a more expensive means of keeping birds healthy, he said they are effective, as chickens that were administered probiotics stayed healthier and grew faster than those that had not been treated with probiotics.

"Eight years ago, I would have said that they're not working in poultry. They're not very useful. Today, I'm saying that they are useful. Expensive, but useful,” he said.