Silly, silly Onder. It's very clear that the zombies took over. In their horrible, homicidal rage they realized the decline of their favorite foods. To capitalize on this, some of the more intelligent and powerful zombies grouped together and started saving human meat and selling it for whatever zombies consider to be currency. This eventually led to large breeding grounds for humans that were not zombified. Much like our cows and chickens. Clearly, female meat is the preferred cut, much like cows instead of bulls. This zombie is only performing his daily job as a butcher, nothing more.