Amino acids are the structural elements of proteins. Proteins have a major role in all body processes. It is the raw material for the formation of muscles, skin, hair, bones, cores, tendons and ligaments. In addition to the form of hormones, enzymes or neurotransmitters, proteins are important for healthy development, good sleep, good metabolic function, as well as regulation of blood pressure and blood clotting. The continuous breakdown and anabolism cycle of proteins increases the demands on their structural components which are amino acids. Especially in horses that are vigorously exercised, amino acids must be given as supplement to avoid protein and muscular decomposition, acceleration of rehabilitation and increase of mass junction. Horses have the potential to synthesize only some of the necessary, for the formation of proteins. The rest, also known as essential amino acids, must be taken up by nutrition.