It’s no longer just foodies at farm markets or Whole Foods buying antibiotic-free, pasture-raised meats.

Increased demand is coming from lots of big players, including Hyatt Hotels; institutional food providers such as Bon Appetit Management Co., which caters to schools and companies; and the fast-food chain Chipotle Mexican Grill. And it’s changing the game.

In fact, this year, Chipotle, which is growing so quickly that it’s opening about three new locations each week, will slowly braise and sell about 120 million pounds of naturally raised pork, chicken and beef that meets its antibiotic-free standards.

The company’s transition to antibiotic-free meat began more than a decade ago when Chipotle realized its pork wasn’t selling very well. And Steve Ells, the founder, wanted to make some changes.

He stumbled upon an article called ‘The Lost Taste of Pork’ in The Art of Eating, a boutiquey, food-lover’s journal, which detailed the practices of Paul Willis, a family farmer in Iowa. Willis raises pigs on pasture, the old-fashioned way. At the time, Willis’ methods were a radical departure from the large, industrial operations that confine pigs indoors and feed them regular doses of antibiotics.

In the article, published back in 1999, writer Edward Behr described a thick pork chop […]