Equine Health

Will Horses Get Too Much Iron From Redmond Rock?

By November 13, 2017 One Comment

Iron overload in horses is a potentially serious issue and there are countless articles written about excessive iron in equine diets, so it’s understandable that many owners want to know if their horses can get too much iron from Redmond Rock products. Because Redmond Rock has a red hue, people assume it has a high iron level. Stated values on the label sometimes add to this perception. Perhaps you’ve seen that the labeling on Redmond Rock and Redmond Rock Crushed states there are 300 ppm of iron in our products and worried that that’s more than your horse should be getting. It’s not, but we know why you might think so, and we hope this post will clear up the confusion.

How to Interpret Mineral Requirements and Label Values

Because you can find a variety of values for iron requirements for horses online, we’re going to stick with what the National Research Council (NRC) states in their book Nutrient Requirements for Horses, (National Academies Press, 1989, 5th edition).  We decided to do this because this committee is made up of numerous researchers from universities all across the United States who review piles of peer-reviewed research data in order to establish the values they suggest. Notice that word: suggest. The NRC makes suggestions instead of mandates because of the variation in results in the studies from which they draw.  

According to NRC values, the iron requirement for horses is 50 mg/kg. Reading that, you might think that Redmond products offer too much iron—however, it’s important to understand how to correctly interpret this information.

The requirement of 50 mg/kg of feed (mg/kg is the same as ppm) means that a horse should have 50 mg of iron for every kg of feed. To get the true limits, you have to multiply 50 mg of iron by the kilograms of feed the animal eats in a day. The suggested RDA for iron as recommended by the NRC for horses is 50 mg/kg (ppm) of feed x 12 kg of feed/day, making it 600 mg/day.

Redmond Salt has iron levels of 300 ppm (mg/kg), so there are 300 mg of iron for every kg of salt consumed.  But unlike eating 12 kg of forage, which is 26 lbs, they are only consuming 2 ounces of Redmond Rock Crushed.


There is a quick formula for calculating how much of a nutrient your horse is getting from Redmond Rock:

simply multiply the ppm on the label by 0.0284 (the factor to get mg/oz).  

For iron: 300ppm x 0.0284 = 8.52 mg/oz.  

At a 2 oz consumption rate, a horse is getting 17 mg of iron/day from Redmond Rock in a diet where 600 mg/day is suggested.


Now that we know what the equine requirements for iron are and how much iron they’re getting from our product, let’s examine how much iron the average horse is actually eating in a day.

Actual Intake of Iron From Feeds

There are many studies showing the iron content of feeds and it’s easy to take samples of your feeds and have them analyzed for iron content.  Here’s an example of a peer-reviewed study that took many samples of different forages to get iron content.  In grasses, the range was from 31 to 1044 mg/kg.  For legumes, it was 29 to 617 mg/kg.  Extrapolating this out using even just a low average of 200 mg/kg, a horse would be consuming 2400 mg of iron every day (200 mg/kg X 12 kg of feed).

Putting It All Together

As you now know, the daily requirement for iron is suggested at 600 mg/day for a mature horse. Redmond Rock and Redmond Rock Crushed offer 17 mg of iron/day. A low average for a forage diet is 2400 mg of iron/day.

It is pretty clear to see that horses normally consume far more iron than they need. When you view it in context, Redmond products’ iron content is almost insignificant in the whole picture–less than 3% of the suggested allowance and not even 1% of actual iron intake.

Horses have been eating huge amounts of iron for eons of time.  How have they been able to do that? How did horses work hard and live long 100 years ago on that diet?

Fortunately, nature has provided protections for this exact problem. Once again from the NRC book, “Iron in feedstuffs and minerals are in the ferric form (Fe+3) and are poorly absorbed in the intestinal tract. Enterocytes regulate iron absorption efficiency, and any more than 2% entering the system is excreted.” (Beard and Dawson, 1997.)

There are many articles like this one that say that iron has a relationship with zinc, copper, and manganese. It’s likely that iron levels aren’t causing a problem as much as an imbalance of this group of minerals.  This is why it’s wise to have your feeds analyzed. Redmond products are unrefined and contain over 60 naturally-occurring trace minerals which can help address this issue of imbalance.

If your horse is having problems, don’t rule out other possible causes like toxins in the feed or other types of feeds in their diet.  Chances are, Redmond Rock isn’t the culprit.

About Redmond Equine

When it comes to your horse’s health, we believe nature has it right. We provide natural, effective equine products that will help your horse get back to optimal health. Redmond products are mined and made in America.