By Eleanor Blazer
Has your horse got "iron-poor, tired blood"?
In the late 1950's Geritol claimed the iron enriched product would cure fatigue. The Geritol ads said the supplement would cure "iron-poor tired blood".
But iron supplementation is not needed, unless the person is anemic due to disease, loss of blood, malabsorption of nutrients, malnutrition or other causes for lack of red blood cells. A balanced diet provides more than enough iron according to the United States Recommended Daily Allowances (US RDA).
So, after years of investigation the Federal Trade Commission ordered the makers of Geritol to amend the claims to say: "only in persons who suffer from anemia (a lack of red blood cells)".
But the myth lives on in the world of horses.
According to the National Research Council's (NRC) Sixth Revised Edition of the Nutrient Requirements of Horses a mature 1,100 pound horse at an average work load would require 400 milligrams of iron a day. The horse with the highest iron requirement, in that weight category, is a lactating mare at 625 mg.
What does that mean to us?
I had some hay tested. The iron level was approximately 42 mg. per pound. If we feed 16 ˝ pounds of this hay (1 ˝ percent of the body weight of a 1,100 pound horse) we would be providing 693 mg. of iron a day.
The forage provides more than enough for the 1,100 pound horse at an average work load. The small amount of iron he would loose through sweat and other bodily functions will be easily replaced with the diet.
The lactating mare would be losing iron through milk production, in addition to normal loss. Her intake of hay should be greater than the 1 ˝ percent of the body weight. She should have access to free choice hay. If her consumption rate was 20 pounds, this would increase her iron level to 840 mg. per day.
Most lactating mares (and many non-lactating horses) are also given other feeds, such as grain and commercial products.
According to the NRC here are some average iron levels in popular feedstuffs given to horses: oats - 80 mg per kilogram (2.2 pounds); barley - 70 mg per kg; corn - 54 mg. per kg and cane molasses - 263 mg per kg.
To make things easy, let's use an average of 65 mg. per kg of iron being provided by the feed. If we feed 6.6 pounds of the feed mix a day we would be providing another 429 milligrams of iron to the horses.
Our 1,100 pound average working horse would now be receiving 1,122 milligrams of iron a day. The lactating mare would be getting about 1,269 mg.
For fun let's look at fresh green grass and iron.
The approximate amount of iron in a kilogram (2.2 pounds) of green pasture is 275 mg (125 mg of iron in one pound of green grass).
Water can also be providing iron. The iron in water is inorganic and harder to absorb, but high levels could increase the iron in the diet.
A popular source of calcium and phosphorus in horse feed mixes is dicalcium phosphate. It can provide as much as much as 1,000 mg/kg of iron in the ration. This source is also inorganic.
Excessive amounts of iron can be toxic. Foals are especially sensitive to iron supplementation and death can quickly follow.
The toxic threshold for iron is generally stated as 500mg/kg of iron in the ration.
Iron absorption is affected by the intake levels. The more iron provided the less it is absorbed. Absorption rates of iron can be anywhere between four to 60 percent, making it difficult to determine how much to provide in a supplement.
Adding iron to the diet should only be done after medical tests have proven it is required. Then it should only been done under the supervision of a vet.
Protect you horse from iron overload by reading supplement labels and avoid ones that add iron to the diet.
Leave the pumping of iron to weight lifters and body builders.
Proper nutrition and management practices can prevent many problems associated with caring for horses. You can learn how to provide your horse with a better life-style by taking the online course "How to Feed for Maximum Performance" taught by Eleanor Richards Blazer.