Ruminant meat includes any meat from animals with rumen. Ruminant animals have multiple stomachs, hooves, and generally eat grass. They’re able to acquire nutrients from plants partly by fermenting the plants in a specialized stomach called the Rumen, through microbial action. Ruminant animals include cows, bison, deer, moose, sheep (lamb), goat, etc. Technically giraffes and camels are in there too. Humans have been eating meat for millions of years, mainly in the form of large ruminant animals.