Creatine

Creatine is a nitrogenous organic compound naturally synthesized from the amino acids arginine, glycine, and methionine. It plays a key role in the regeneration of adenosine triphosphate (ATP), particularly in muscle tissue, by acting as a phosphate donor in the creatine phosphate energy system.

it is most commonly found in formulations aimed at performance horses, although its use in equine nutrition is not as widespread or well-researched as in human or other animal species.