If You're Wondering Where Your Big Mac Came From, There are 400,000 Possibilities

McDonald's said yesterday that it would start buying "sustainable beef" in 2016 - even though the company doesn't know what that means - to keep up with growing demand for ethically-sourced meats.

So where, exactly, does your McDonald's hamburger meat come from today?

There are more than 400,000 possibilities, according to a report by GreenBiz.com.

"McDonald's doesn't buy beef directly from ranchers or slaughterhouses. It buys finished, frozen patties from about 20 food processing companies globally," Joel Makower reports. "Cows and beef may change hands four or five times between farm and finished patties."

Frozen patty suppliers include Keystone Foods and Lopez Foods, which has been making patties for McDonald's for more than 40 years.

"When you trace the hamburger supply chain upstream, you find yourself at one of the roughly 400,000 cattle farms that provide meat that eventually ends up in a McDonald's burger, many of them small operations with 50 or fewer head of cattle," Makower continues.

"They are the beginning of a value chain that includes ranches, dairy farms, cattle stockers, feedlots, beef packers and processors. Along the way, cows are raised, fattened and slaughtered, and the resulting beef is trimmed, ground, mixed with other beef, formed into patties, inspected, packaged, frozen, shipped to distribution centers and, eventually, to one of McDonald's worldwide restaurants."