Per McDonald's website, all the beef patties used in its U.S. locations come from a company called Lopez Foods, the chain's main beef supplier for over three decades.

Based in Oklahoma City, Lopez Foods — or Lopez-Dorada Foods, to use its full name — calls itself a "protein-processing" specialist, meaning it handles all kinds of meat products.

All the "fresh and frozen ground beef” supplied to McDonald's is USDA-inspected and checked for safety, as Lopez Foods is part of the Global Food Safety Initiative.

Lopez Foods also keeps undergoing third-party audits from organizations like the U.S. Roundtable for Sustainable Beef, so there’s seemingly no need to worry about animal welfare.