Perdue ended the routine use of antibiotics used in human medicine two years ago, and says this new announcement marks the final step away from the routine use of any antibiotics, and will increase the amount of zero-antibiotics chicken available for consumers.

The company's chairman Jim Perdue said the move helped to address consumer concerns.

"Some of our competitors are promising to reduce antibiotics, and others are trying to tell consumers it doesn’t matter, but our consumers have already told us they want chicken raised without any antibiotics," he said.

Another large US poultry company, Sanderson Farms, has previously labelled zero antibiotics chicken as a 'marketing gimmick'.

Ionophores removed from routine use

The latest announcement from Perdue is that the company has ended the use of animal-only antibiotics known as ionophores. Ionophores are commonly mixed into poultry feeds to control the intestinal disease coccidiosis.

Some companies have argued that ionophores should be exempted from efforts to reduce antibiotic use in agriculture, as they are not considered important to human medicine. McDonald's USA is one company that is reducing overall antibiotic use but continuing to use ionophores.

Perdue said the company's experiences raising organic chicken had helped them to reduce antibiotic use.

“Through our experience raising no-antibiotics-ever chickens for almost a decade and exposure to organic production, we’ve learned to prevent diseases without antibiotics,” said Bruce Stewart-Brown, DVM, senior vice president of food safety, quality and live production. “If you can raise healthy chickens without routinely using antibiotics, why rely on them?”

On average, five per cent of flocks at Perdue will still receive antibiotic treatment for conditions, but these chickens are removed from the 'no-antibiotics-ever' programme and sold through other channels.