McDonald's US restaurants will also offer customers milk jugs of low-fat white milk and fat-free chocolate milk from cows that are not treated with rbST, an artificial growth hormone.

"Our customers want food that they feel great about eating -- all the way from the farm to the restaurant -- and these moves take a step toward better delivering on those expectations," said McDonald's US President Mike Andres.

McDonald's has been working closely with farmers for years to reduce the use of antibiotics in its poultry supply.

This new policy supports the company's new Global Vision for Antimicrobial Stewardship in Food Animals introduced this week, which builds on the company's 2003 global antibiotics policy and includes supplier guidance on the thoughtful use of antibiotics in all food animals.

The move has been welcomed by the campaigning congresswoman Louise Slaughter, who has been calling for an end to the liberal use of antibiotics in livestock.

“Today’s announcement from McDonalds is encouraging, but until there is an enforceable, verifiable limit on agricultural antibiotic use, we will have no way to verify whether chicken raised on medically important antibiotics has been truly phased out,” she said.

“Furthermore, I have called on McDonald’s to also phase out beef raised on medically important antibiotics, and I will continue to press them on that front.

“This is proof that when an enlightened public demands change, companies respond. Consumers do not want to risk the health of their families by feeding them meat and poultry raised on antibiotics, and they are voting with their wallets.

“With over 50 city councils across the country and 450 independent health and consumer advocacy groups supporting my bill to get antibiotics off the farm and save them for humans, momentum is growing.

“That pressure needs to be directed at Congress and the FDA as well, who have failed to stem the looming antibiotic resistance crisis.

“Until we have a true legal limitation on antibiotic use on the farm, we will still be at risk of frittering away one of the greatest medical advancements of the modern era.”

All of the chicken served at McDonald's approximately 14,000 US restaurants comes from US farms which are working closely with McDonald's to implement the new antibiotics policy to the supply chain within the next two years.

"McDonald's believes that any animals that become ill deserve appropriate veterinary care and our suppliers will continue to treat poultry with prescribed antibiotics, and then they will no longer be included in our food supply," said Marion Gross, senior vice president of McDonald's North America Supply Chain.

While McDonald's will only source chicken raised without antibiotics important to human medicine, the farmers, who supply chicken for its menu, will continue to responsibly use ionophores, a type of antibiotic not used for humans that helps keep chickens healthy.

"If fewer chickens get sick, then fewer chickens need to be treated with antibiotics that are important in human medicine. We believe this is an essential balance," Ms Gross added.

In another move, McDonald's US restaurants later this year will offer milk jugs of low-fat white milk and fat-free chocolate milk from cows that are not treated with rbST, an artificial growth hormone.

The milk jugs are popular choices in Happy Meals.

"While no significant difference has been shown between milk derived from rbST-treated and non-rbST-treated cows, we understand this is something that is important to our customers," Ms Gross said.

All of these actions are the latest steps in McDonald's USA's journey to evolve its menu to better meet the changing preferences and expectations of today's customers.

In addition to the menu sourcing changes, McDonald's USA this week was announced as a founding member of the newly formed U.S. Roundtable on Sustainable Beef.

This engagement is a critical step in support of the company's global commitment and effort to source verified sustainable beef.

"We will continue to look at our food and menu to deliver the kind of great tasting and quality choices that our customers trust and enjoy," Mr Andres added.