Selenium and its roles:
Selenium affects several systems:
- blood circulation
- immune response system
- individual cell function
Selenium is the catalyst of one enzyme: the glutathione peroxidase. This enzyme controls the efficacy of the most powerful intra-cellular anti-oxidant: glutathione. The supply of selenium in feed must be closely controlled because excess amounts can cause a condition known as blind staggers. It influences various metabolic processes and it is closely associated with vitamin E.
The bioavailability of selenium is affected by other nutrients such as sulphur and ferric iron.
The needs for selenium are estimated at 0.04 mg per day and per kg of metabolic weight. But in case of important stress or training this value could be multiplied by three.
The metabolic weight corresponds to the horse's weight to the power of 0.75: for example a horse of 450 kg : 4500.75 = 98 kg of metabolic weight; such a horse will need 3.9 mg of this trace element per day.