Minerals provide material for the growth of bones, teeth, tissues and also help to regulate many of the body's chemical processes. They also help in tissue repair, reproduction, muscular activities and body heat. Minerals can be categorized as macro-minerals and micro-minerals, macro-minerals are required in the body in larger amounts and micro-minerals are needed in smaller amounts.
Macro-minerals
Macro-minerals
- Calcium:is required for the development of bones and teeth.Blood clotting, muscle and nerve function and enzyme activation (Agar,2003).Found in forage, hay & green vegetables.
- Chloride:is required for osmotic pressure, acid - base and water balance (Agar,2003). Is found in feed but can also be through salt blocks.
- Magnesium:is needed for the development of bones and teeth, energy metabolism, enzyme activation (Agar,2003).Found in complete feeds as well as green vegetables.
- Phosphorus: is needed for development of bones, teeth, energy utilization, enzyme systems, phospholipids in cell membranes & constituent of nucleic acids (Agar,2003). Found in eggs, meat & vegetables.
- Potassium: is required for nerve & muscle action, protein synthesis and the maintenance of osmotic pressure (Agar, 2003). Found in most forages, cereals,fruit & grains.
- Sodium: is required for nerve and muscle action, osmotic pressure (Agar,2003).Found in vegetables, fruit, salt blocks.
Micro-minerals
The minerals with known dietary requirements are:
- Copper: which is needed for bone and haemoglobin formation, melanin production(Agar,2003).
- Iodine: which is a component of the growth hormone thyroxine (Agar,2003).
- Iron: which is a component of haemoglobin and myoglobin. Its used in the utilization of oxygen and is also a constituent of enzymes (Agar,2003). Found in forage & green vegetables.
- Manganese: is an enzyme activator, growth factor in bone development and a component of connective tissue (Agar,2003).
- Selenium: is linked with Vitamin E and is also a component of an enzyme - gluthathione peroxidase - acting as an anti oxidant (Agar,2003).
- Zinc: is a component of enzyme systems including protein synthesis, helps with wound healing and a healthy immune system (Agar,2003). Can be found in supplements and complete feed, fruit, vegetables and grains.
Excessive mineral intake can be toxic to some species and can even lead to death. Sheep are susceptible to copper toxicity which can lead to death and symptoms of this can include lethargy, anemia, pale membranes, thirst and jaundice according to Bremner 1998. Excess of some minerals can cause weight loss and slower rates of gain in some animals, cattle that have an excess of sodium and chloride can have reduced milk production and weight loss. Selenium toxicity in horses can cause appetite loss, hair loss, paralysis and eventual death.
A horse with a supplemental selenium intake in excess of 5 mg per day might suffer from selenium toxicity if his forage and feed already provide adequate selenium; the maximum tolerable level of selenium in a horse’s total diet is only 20 mg per day. As little as 50 mg per day total intake can result in mild signs of toxicity (loss of mane and tail hairs, horizontal hoof cracks). Animals consuming more than 1 gram per day--or those that are inadvertently overdosed with selenium even once--can develop acute selenium poisoning, which will rapidly cause death (as in the 2009 deaths of several polo ponies due to a medication error). Clinical signs of acute selenium poisoning include gait abnormalities, garlic breath odor, labored breathing, and muscle tremors. This poisoning can be life-threatening depending on the amount consumed. Overdoses can also be fatal for foals (Mendell,2006).