Subway said on Tuesday that it plans to transition to a supply chain that uses only meat raised without antibiotics by 2025.

The Milford, Conn.-based sandwich giant, which already plans to shift its 27,000 U.S. restaurants to antibiotic-free chicken by the end of next year, now plans to shift its supply chain to antibiotic-free turkey, pork and beef over the next decade.

Subway is the largest chain to make such a broad commitment to antibiotic-free proteins.

“Today’s consumer is ever more mindful of what they are eating, and we’ve been making changes to address what they are looking for,” Dennis Clabby, executive vice president of Subway’s Independent Purchasing Cooperative, said in a statement. “A change like this will take some time, particularly since the supply of beef raised without antibiotics is extremely limited and cattle take significantly longer to raise. But we are working diligently with our suppliers to make it happen.”

The company expects to finish its shift to antibiotic-free chicken by the end of next year. It will introduce antibiotic-free turkey next year and complete that transition within two to three years. Pork and beef will take another six years to complete, with the full transition of the company’s supply chain expected by 2025.

The move comes amid heightened concern about the use of antibiotics to promote growth in proteins, particularly poultry, amid fears of their contribution to antibiotic-resistance among bacteria.

It also comes amid growing concern from restaurant customers about the ingredients in restaurant food. Subway earlier this year announced plans to remove artificial colors, flavors and preservatives from its sandwiches, salads and cookies by the end of 2017.

Subway said it is taking a long time to make the transition to ensure that it can do so without raising prices or sacrificing taste.

“Given the size and scope of the Subway brand, this commitment is the largest of its kind in the restaurant industry,” Clabby said. “We hope that this commitment will encourage other companies in our industry to follow our lead and that, together, this will drive suppliers to move faster to make these important changes for consumers.”

Consumer and environmental groups have been pressuring Subway in recent months to stop using livestock raised with antibiotics that promote growth. Some praised Subway’s move on Tuesday, and noted the company’s immense size and ability to impact the supply chain. “We applaud Subway for living up to their healthy image and making a commitment to sell meat raised without antibiotics,” Jason Pfeifle, public health advocate with the California consumer group CALPIRG, said in a statement. “They have more restaurants in the U.S. than any other chain, and this announcement will put major market pressure on meat producers to stop overusing antibiotics.”

Update: Oct. 20, 2015 This story has been updated to reflect responses to the initiative.

Contact Jonathan Maze at [email protected]

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