In-N-Out Burger, a popular West Coast restaurant chain, said it is moving toward antibiotic-free beef, according to reports the first week of March.

Keith Brazeau, the company’s vice president of quality, told Reuters that In-N-Out  Burger is committed to beef that is not raised with antibiotics important to human medicine. "We've asked our suppliers to accelerate their progress towards establishing antibiotic alternatives," he said.

The decision reportedly comes after the company received a letter calling on it to stop selling beef from animals produced with the routine use of antibiotics and to commit to a strong antibiotics policy.

In-N-Out Burger joins restaurants like Panera Bread Co., Chipotle Mexican Grill Inc. and Shake Shack Inc. that have already committed to sourcing only antibiotic-free meat. Last year, McDonald’s also set a timeline for 100% antibiotic-free chicken by 2017, while Subway said all of the meat it sources will be antibiotic free by 2025.

The California-based restaurant chain opened its 300th store last year and continues to expand throughout the West Coast.