What’s the metal on Iron?

Whilst this post outlines the actions and requirements of iron for the horse, never forget that no mineral or vitamin ever actions in isolation.  Supplementing with a single mineral is often ineffective due to the complex interactions of chemical compounds in the body. Equilibrium and LexveT were designed to overcome this by being a balanced broad-spectrum vitamin and mineral supplement.

What does my horse need iron for?

To transport oxygen from the lungs to organs and tissues around the body. It is absorbed into the blood stream by combining with the protein molecules of haemoglobin and myoglobin. Life as we know it would not exist without this vital element.

A 500kg horse contains approximately 33 grams of iron in its body – 60% of that iron is in haemoglobin in red blood cells, 20% is in myoglobin in muscles, 20% is in storage and transport in the body and approximately 0.2% is in body enzyme systems.

How much iron is needed in the diet?

It is estimated that most horses require 40mg iron per kg of feed/dry matter eaten per day.  Pregnant and lactating mares and foals require approximately 50mg/kg of food ingested.

What are the sources of iron in the diet?

Forage contains approximately 100-250mg iron/kg and grains from 40-50mg/kg.  Free grazing horses also ingest iron from consuming soil attached to plants.  The absorption of iron from these sources into the body is typically low at approximately 5-10%.  A high level of iron in soil and feed stuffs does not mean that all or even most of it is absorbed.

How is iron absorbed by the body?

Iron in the diet is absorbed by the enterocyte cells lining the but wall where they remain in storage until the iron is needed by the body.  The incorporation of iron into the cell is a tightly regulated process as is the release of iron from the cell into the blood stream.  Any stored iron in the enterocyte is lost to the body when the cell dies and is removed in manure.  The absorption of iron by the body is a dynamic and variable process depending upon the bodies needs at that point in time.

How is iron stored in the body?

The body is very effective at scavenging and retaining iron from the regular breakdown of red blood cells.  It is stored in the liver and the reticuloendothelial system to be used again.  In a normal healthy horse the body has very efficient and sophisticated mechanisms to prevent iron overload and iron deficiencies.  It is strongly suspected that horses suffering from chronic inflammatory diseases e.g. Equine Metabolic Syndrome, Laminitis, Insulin Resistance, Gastric Ulceration etc. store extra iron in the liver SECONDARY to a predisposing problem, in other words, elevated iron levels in the liver are a symptom of these conditions.  Feeding less iron to these horses will not resolve the primary problem.

Because the body has a tightly regulated mechanism for the absorption and storage of iron, evolution did not dictate that an excretory pathway was necessary.  In a normal adult horse, the body does not keep on absorbing iron in excess of its needs.

How can an iron deficiency develop?

Iron deficiency is rare in the horse, but when present, is usually seen in horses with blood loss e.g. Gastric Ulcers, Pulmonary Haemorrhages, sever injuries and parasitism. Blood tests can confirm if a horse is anaemic.  Mares milk has reduced levels of iron as lactation proceeds and the foal gains the extra iron needs by starting graze and ingest solids.

Iron is also lost in sweat – a horse in heavy work can lose up to 25-30 litres of sweat in a day which can result in a potential loss of 500mg of iron.

Iron Toxicity

Excessive supplementation of iron especially to young foals can result in death from liver failure.  Accidental overconsumption of an iron supplement by an adult horse can lead to damage to the lining of the gut wall and excess iron enters the blood stream.  This can cause damage to the heart, liver, kidneys and other organs.  Iron fed at recommended rates by supplement manufacturers pose no problems to a healthy horse.  Injectable iron products should be used with great caution as they circumvent the mechanisms that prevent excess iron being absorbed via the digestive system.

Supplementing with iron

Never supplement with any mineral in isolation. Horses need to be fed a balanced and appropriate multimineral/vitamin supplement at all times.

Feeding extra iron in the diet will not increase food intake, red blood cell count, haemoglobin concentration or packed cell volume.  High levels of iron in the diet can decrease serum and liver zinc levels but will have no effect on serum levels of iron, calcium, copper and manganese.

Equilibrium Mineral Mix and B1 Cool Mix can be fed with confidence and safety to all horses.  It is balanced in its mineral composition and supplies what in lacking in most horse’s diets.

 

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