Iron in Perspective
Because excess iron cannot be excreted, there is concern that many horses suffer from iron over-load.
When you have pasture analysed, iron readings tend to be high, usually made higher by soil contamination on the sample. This is virtually impossible to avoid as is the ingestion of excess iron by the horse whilst he is grazing short grass.
Although it varies regionally, soil is inherently high in iron** so the shorter the grass, the higher the iron intake because of the close proximity of the mouth to the ground.
The iron levels in the attached graph have been obtained from Forage Analyses done by Calm Healthy Horses and clearly shows how short grass (< 2”) contains the highest iron levels by far. Long grass (> 8”) has lower iron levels and hay even lower.
The Daily Requirement, for a 500kg horse, according to the NRC Nutrient Requirements of Horses, is 400mgs/day (500 for horses in intense work, 625 for lactating mares. Horses living on short grass have an iron intake which far higher than the Daily Requirement. Water which is high in iron can also be another underestimated source.
The GOOD NEWS is that, because this iron isn’t in a bio-available form, most of it does not get absorbed anyway. Around 80-85% goes through the digestive system and out with the manure.
The iron that is absorbed by the horse is particularly important for optimal health. It is an essential element for the production of blood, for the transport of oxygen plus other roles such as assisting enzymes to perform the trillions of chemical reactions needed for life to go on.
If you are concerned about iron overload, the most effective remedial action you can take is to manage your horse’s grazing in such a way they are not living 24/7 on short grass. Having a high hay diet reduces iron intake substantially.
It is also essential to ensure optimal copper levels because copper is required for iron to perform its functions. And you need 3 x as much zinc as copper (Premium NZ Horse Minerals and Premium MVA are ideal options and take care of these ratios and everything else for your horse)
** Iron, chemical symbol Fe, is the fourth most abundant element available on Earth, according to the University of Wisconsin.