Manganese (Mn) is an essential dietary trace mineral that is also used in industrial processes, such as battery manufacturing. However, long before Mn was known to be useful for these applications, early humans used black/brown colored Mn dioxide as a color pigment. Cave paintings estimated at 30,000 years old are reported to contain Mn and, even prior to these cave paintings, researchers suspect Mn might have been used as a cosmetic product.

Manganese was first indicated as an important nutrient to plants before it was later shown to be essential to mammals in a study conducted in rats in 1926 (McHargue), followed by a study in swine in 1928 (Skinner and co-workers).

Today, Mn is known to have multiple functions, but, most notably, Mn plays a role in bone formation. Enzymes involved in chondroitin sulfate (which is necessary for cartilage formation) synthesis require Mn. Manganese is also involved in fatty acid synthesis, amino acid metabolism, energy metabolism, and the antioxidant system.

A multi-faceted mineral indeed, especially considering that an average 500-kilogram (approximately 1,100-pound) adult horse at rest or lightly exercised only requires about 400 milligrams per day (National Research Council’s Nutrient Requirements of Horses, 2007).

In ruminant animals, swine, and poultry, Mn deficiencies are most notable in newborn or young animals. In particular, Mn deficiency can result in weak newborns that can show incoordination or have leg deformities and weak bones. In horses, however, a Mn deficiency has never been confirmed in a newborn or young foal.

Forage and grain Mn concentrations are dependent on soil Mn concentrations, which tend to vary. Typically, Central Kentucky pastures aren’t reported as Mn-deficient, and with unrestricted pasture access, an idle or lightly exercised mature horse should be able to meet its recommended daily Mn requirements by consuming pasture alone. Any commercial feeds or supplements will also be formulated to provide Mn in sufficient quantities to meet your horse’s requirements when fed according to the manufacturer’s guidelines.

If you live in an area known to have low soil Mn content, buy forage for your horse from a low-Mn area, or simply are concerned about your horses Mn intake, contact an equine nutritionist. A nutritionist can assist you to appropriately evaluate all the sources of minerals in your horses’ complete diet, ensuring that all mineral requirements are met and balanced.

Author: Mieke Holder