Animal species, life stage, health and nutritional status all affect the bioavailability of minerals. Factors relating to the diet are level of intake (in relation to requirements), intake of other minerals and intake of substances which may enhance or impair the absorption of the mineral in question. Lastly, there are factors related to the mineral compound used, such as water solubility and chelating qualities of the mineral.
The bioavailability of minerals in horses is sometimes different from other animal species. The interactions between calcium and phosphorus, between zinc and copper or between calcium and zinc, are generally supposed to occur in men and domestic and experimental animals.
The same is true for interactions between minerals and compounds of the diet, such as fat and calcium or phytate and phosphorus or zinc. In horses, only a few of these interactions have been verified and they may not exist or may be somewhat different. On the other hand, it makes sense to take into account the possibility of interactions between dietary compounds and mineral availability when formulating rations for horses, even if some of these interactions have never been demonstrated in horses.