Some proteins are so complex and chemically ‘solid’ that they cannot be broken down by digestion so the amino acids cannot be absorbed in the intestine.They accordingly have no dietary or nutritional value for the animal.This is the case with feathers and hair for example.
A little background information
Amino acids are the building blocks of proteins and their derivatives. Proteins contain a total of about 20 amino acids, only 11 (cats) or 10 (dogs) of which must be provided in food as they are not produced by the body. Other amino acids must also be provided in food, but they make up a relatively smaller proportion of the total protein intake, as their role is less specific.
Its role in the body
Amino acids from dietary proteins are the building blocks of all proteins synthesised by the body to ensure its vital operation and physiological functions.
Natural sources
All food proteins of animal or plant origin are composed of a series of chemically bound interlinked amino acids.