For example, I could put together a "high protein" dog food where the protein is composed of an indigestible substance such as feathers, hide or hoofs. Sure, the protein level by analysis might be high (and even the experts don't agree as to just what amount qualifies as "high" protein level in a food) but if the dog's gastrointestinal tract is unable to break the protein molecules down into amino acids and then absorb and utilize those amino acids, the diet is worthless as a food source for the dog! So "high protein" on the label means absolutely nothing; you've got to read the ingredients label to see if the source of protein is digestible. See Table #1 to compare the approximate digestibility of the more common dog food ingredients. Egg white protein is used as the benchmark, giving it a value of one (1) since it is so highly digestible. Other protein sources are then compared to egg whites regarding their digestibility
