"(5) Filled milk means any combination of nonmilk fat or oil and milk, whether or not it is fresh, cultured, reconstituted or modified by the addition of nonfat milk solids, with or without milkfat, so that the product, including stabilizers, emulsifiers or flavoring, resembles milk or any other fluid milk product, and contains less than six per cent nonmilk fat or oil." . . . .