All of the above may be related to magnesium deficiency in horses. Horses need a minimum of 15 grams of magnesium per day that is essential for efficient muscle enzyme reactions. This increases with exercise as it is sweated off as demands are increased. Also, horses in work are usually stabled, denying magnesium access from pasture. Re-Place MG can help restore the imbalance. It is soluble and tasteless and can be easily mixed in a cup of water and poured onto the feed.