Digest is an animal feed-grade ingredient that must be made soluble with the use of prolonged heat and moisture, or chemicals and enzymes (e.g. Poultry feet= "Poultry Digest"). (Dr. Corinne Chapman, Rocky Ridge Vet Care) A material which results from chemical and/or enzymatic hydrolysis of clean and undecomposed animal tissue. The animal tissue shall be exclusive of hair, horns, teeth, hooves and feathers except in trace amounts that might occur unavoidably in good factory practice. (AAFCO, 2003) Wikipedia describes animal digest as "a cooked-down broth" which can be made from unspecified parts of unspecified animals. The animals used can be obtained from almost any source and no control is in place over quality or contamination. Any kind of animal can be included: "4-D animals" (dead, diseased, disabled, or dying prior to slaughter), goats, pigs, horses, rats, euthanized at animal shelters, restaurant and supermarket refuse, etc. In other words, digest does not give any indication of what exactly it is, and is a very processed, poor source of nutrition.