BOSTON ( TheStreet) -- Chipotle Mexican Grill ( CMG) opened 25 new restaurants last quarter, and comparable-store sales, a measure of growth for existing locations, increased 8.7%. The Chipotle brand continues to win new customers, even in established regions.Unlike competitors, the company forgoes a franchise model, allowing management a greater degree of control over ingredients and brand. Chipotle makes a concerted effort to avoid factory-farmed protein. Its pork, chicken and beef come from so-called naturally raised animals, which are treated humanely and never given antibiotics. Only 35% of Chipotle's dairy products come from pasture-raised cows, but a prodding of suppliers is boosting that figure. Founder Steve Ells, a graduate of the Culinary Institute of New York, is the root of the company's social responsibility. After working as a line cook in San Francisco, he opened the first store in Denver with an $80,000 loan from his father. The original Chipotle is situated in a former Dolly Madison Ice Cream Store. Ells, a chef, not a businessman, projected that 107 burritos a day was the break-even point for his fledgling enterprise. Within two months of operation, the restaurant was selling more than 1,000 a day and generating enough cash for a profitable expansion. The company was seeded by McDonald's ( MCD) in 1998, allowing rapid development. McDonald's divested its position in 2006 after Chipotle went public. Chipotle's stock doubled on the first day of trading.