Meat-By-Product in Pet Food

This information came from my research anyone can find online.

Meat by-products : are ground and cleaned parts of slaughtered animals, not including meat. These include undeveloped eggs, feet, necks, heads, (and a small amount of feathers in the case of chicken meat), lungs, spleen, kidneys, brain, liver, blood, bone, and stomach and intestines freed of their contents. It does not include hair, horns, teeth, or hooves. The definition for meat by-products by the Association of American Feed Control Officials is:

The non-rendered, clean parts, other than meat, derived from slaughtered mammals. It includes, but is not limited to, lungs, spleen, kidneys, brain, livers, blood, bone, partially defatted low temperature fatty tissue, and stomachs and intestines freed of their contents. It does not include hair, horns, teeth and hoofs. It shall be suitable for use in animal food. If it bears name descriptive of its kind, it must correspond thereto.

These meat-by-products are commonly found in lower-grade pet foods and even many larger brand names.