Chipotle said it would suspend pork sales at about a third of its U.S. restaurants, following a routine audit that revealed one of its suppliers was not complying with its animal-welfare standards.

The inspection of the undisclosed supplier exposed some inconsistencies in protocol, communications director Chris Arnold said. Suppliers must raise pigs with access to the outdoors or in deeply bedded barns to improve their comfort. They cannot use antibiotics. "We could fill that shortfall with conventionally raised pork, but the animal welfare standards fall well short of our requirements, and (we) simply aren't willing to make that compromise."

Chipotle will not serve "carnitas" at some of these restaurants, rather than use conventionally raised pork, said Arnold. Instead, the burrito seller is looking at a host of options to address the shortfall, including procuring additional pork from existing suppliers or finding more suppliers.