When In-N-Out Burger first opened in 1948, the company only provided a basic menu of burgers, fries and beverages. The foods it prepared were made on-site from fresh ingredients, including its french fries which were sliced and cooked to order. Unlike other major competitors in the hamburger fast food restaurant business (Burger King, McDonald's and Wendy's), as the chain has expanded over the years, it has not added products such as chicken or salads to its menu since 1976 and has never changed its preparation methods. The company utilizes a vertical integration model for its raw ingredients, procuring and manufacturing much of its food supplies in-house. The company does not utilize freezers in its operations, shipping food daily to its stores from its facilities. Instead of a broad menu like other competitors, In-N-Out has become known for its "secret menu", or unadvertised variations of its burgers that are based on customer preferences, such as the popular "Animal Style". Burgers All burgers consist of one or more beef patties cooked to "medium-well", and served on a toasted bun. The standard style of burger includes tomato, hand-leafed lettuce and "spread", a sauce similar to Thousand Island dressing. Meat For most of its history, In-N-Out has produced its own meat in company-owned facilities. The chain has a policy of using only fresh meat, and all of its stores are supplied by its California manufacturing operations located in Baldwin Park. With its expansion into Texas, the restaurant opened its first production plant outside of California in a suburb of Dallas in order to increase its geographic footprint. By keeping the manufacturing process in house, the chain is able to maintain strict quality control standards. Beginning in March 2016 the company announced that it would move forward to sourcing its beef from cows that have not been treated with antibiotics. The chain did not announce a timeframe for the switch, but that it would move forward at an expedited pace. Part of the reason for the switch was that California passed a series of laws to ban the use of antibiotics in non-medical, prophylactic treatments. Additionally, several groups of consumer advocacy NGOs, led by CalPIRG, had been pressuring a number of restaurant chains to stop using meat raised with low-dose antibiotics. Secret menu variations The bulk of the secret menu revolves around the burgers. In-N-Out's own website acknowledges the existence of this secret menu, publicizing