Quiessence is a popular magnesium chromium supplement for horses that provides magnesium in two different forms- as magnesium oxide and as magnesium protonate- for maximum GI intake.

Magnesium oxide (MgO) is a compound made up of magnesium and oxygen commonly used as a dietary supplement, as well as an antacid and a laxative. Magnesium oxide is a highly concentrated form of magnesium and is used to supplement the diet when the horse's diet is lacking in sufficient magnesium, or when the horse's requirements for magnesium are increased, such as during times of stress, heavy exercise, or during pregnancy.

Magnesium proteinate is a form of magnesium supplement bound to protein. Magnesium proteinate is considered a particularly bioavailable form of magnesium, resulting in better absorption and utilization of the mineral.