Minerals are an essential part of any horse’s diet, despite the fact that, like vitamins, they contribute no energy whatsoever. Without minerals, horses would not be able to metabolise fats, proteins or carbohydrates. Their muscles and nerves would not function, nor would their bones be able to support their weight.
Minerals are divided into two categories: Macro minerals which include calcium, phosphorus, magnesium, sodium, potassium, sulphur and chlorine are needed in larger quantities in the daily diet. Micro minerals or ‘trace minerals’ such as iodine, manganese, iron, cobalt, zinc, copper and selenium are required in lesser trace amounts but are never the less just as vital to the horse.
All minerals can have an adverse effect if present in the diet in large enough or unbalanced amounts, but there is a broad safety zone.
The danger of minerals is that some are linked, so one should not supplement single minerals only. Feeding the maximum or minimum of one mineral can affect the absorption and utilization of another.
Calcium and phosphorus are both essential to the growth and repair of healthy bone, but must be present in equal amounts, with at least as much calcium as phosphorus (never the reverse) in order to perform their function. Copper, zinc and iron with smaller quantities of magnesium and manganese form yet another linkage, to encourage bone density.
To complicate matters even further, the absorption of minerals in the horse’s gut varies widely, with some being far easier to absorb than others.
The summation to minerals is to feed a complete and balanced mineral supplement and never add any one mineral on its own. Material taken from papers written and accepted by the National Research Council’s “Nutrient Requirements of Horses”