MPCO ONE AC Supplement (200gm) ONE AC is a powder feed supplement for horses. It is a patented nutritional supplement developed specifically for the non-sweating horse. The ability to sweat is an essential physiological response in the horse if it is to perform in hot and humid climates. Failure to sweat (anhydrosis), can reduce the equine athlete's ability by 15-20%, and jeopardize its life if forced to perform. ne package of ONE AC will last one horse approximately 30 - 32 days.