In the US, the FDA publishes Filth Standards for Food products, setting what are terrmed "Action levels":....
I have heard the expression "The more you know about what goes into sausage and politics, the less you want to have anything to do with them." It seems that mikewint has considerably broadened the former category.
Somehow, I have always pictured whole turkeys being dropped into a hopper at one end of a big machine, and at the other end, a pile of feathers, a pile of beaks, and slices of TurkeyB---- (since N4521U has declared this a dirty word, I cannot use it in this forum).
This above process was only developed after the failure of the attempt to create turkey-pork products by gluing snouts and curly tails onto young turkeys.
-Jim