There are also animal by-products in your pet food! (And that has nothing to do with quality.)
Animal by-products are then divided into 3 categories :
Category K1: sick parts and deceased pets - this meat will be discarded.
Category K2: dead (i.e. not slaughtered) animals or, for example, meat with foreign bodies in it - this meat is also discarded, but can also be used for e.g. the leather or cosmetics industry.
Category K3: Meat that is not hazardous to health (e.g. with discoloration, deposits, scarring), but would not be bought by humans. Or organs, e.g. liver, which have been judged to be suitable, but which a pet food dealer wants to buy. Purely by this purpose, it automatically becomes K3 material.