NEW YORK — Subway says it plans to switch to meat raised without antibiotics over the next several years after a coalition of advocacy groups planned to deliver petitions to the company's headquarters Thursday calling for the change. The sandwich chain had already said this summer that it would switch to chicken raised without antibiotics important to human medicine by next year. Now, it says it will serve chicken that receive no antibiotics starting in March. It will also make the change to turkey starting sometime next year, with a transition expected to be complete within two to three years. Pork and beef raised without antibiotics will follow within six years after that, or by 2025, the company said Tuesday.