Magnesium to Relax Equine Muscles and Nervousness

white-horseDTMagnesium is another one of those minerals that is usually in crazy low amounts in horse feeds and supplements.

But since magnesium is the best way to relax both the horse’s muscles and nervous system, it should absolutely be a staple daily supplement. Don’t forget that the heart is also a muscle. And the intestines (colic anyone?) are composed of visceral muscle cells that contract and move food along. The last thing you want is to have any of these important muscles cramping or spasming from magnesium deficiency. Magnesium is also really important for pregnant mares – because the uterus is one big muscle!

Magnesium Not Well Absorbed

The esteemed PhD equine nutritionist, Dr. Juliet M. Getty says that many horses do not receive enough magnesium from pasture or hay, because it is not well absorbed. The medicinal dose (to address deficiency) is 10,000 mg/day (for a 1000 lb horse). And Dr. Getty recommends 5000 mg/day as a maintenance dose.

A Note About Supplement Labeling

If you read through the comments section below, you’ll see I had quite a bit of back-and-forth on this issue with an equine professional until finally realizing that supplement labeling regulations are very different for animal vs human supplements! So that bag of bulk magnesium oxide at your local feed store, may be labeled (for example) as: Magnesium Oxide……54%.

Now here’s the tricky thing, that supplement may actually contain 93% magnesium oxide, but the label claim is only referring to the amount of elemental magnesium – not the oxide part of the compound. I have no idea why they have regulated this way as it would be far less confusing to follow the human format, or, to list as:

Magnesium oxide…..93%
– Magnesium…..54%
– Oxide…..39%.

But as you can see from this feed-grade spec sheet – that is the way it is regulated, and the remaining 7% is composed of calcium oxide, silica oxide and iron oxide.

Best Form & Dosage of Magnesium for Horses

Magnesium oxide is the form of magnesium usually given to horses and livestock – probably because it is usually the cheapest form and it has a very neutral taste. Magnesium citrate has a much better absorption rate than magnesium oxide, but it is super tart in flavor, so many animals won’t eat it. Magnesium carbonate has a decent absorption rate and is also fairly neutral in taste.

You can either get Magnesium Oxide from Dr. Getty’s supplement store (free shipping in continental USA) where 1 tablespoon = 10,000 mg. So the maintenance dose for horses would be half a tablespoon (half a scoop – 5,000 mg) per day. A 5-pound bag would give you 454 servings. That works out to a cost of $0.08 per serving – or $37.95 for 454 servings.

Or you can purchase Bulk Supplements Magnesium Carbonate where 1 level tsp = 698 mg. So you would give about 7 and 1/6 level teaspoons per day for a 5000 mg/day maintenance dosage. That works out to a cost of $0.42 per serving – or $83.44 for 200 servings (4 bottles).

Many horses don’t like loose powders – and possibly cannot eat much powder unless they’re willing to lick it – so I sprinkle magnesium and any other supplements I’m giving in powder form onto their feed or veggies, and then pour flax or Udo’s oil over top of the powders to make it easier to eat.

Magnesium Horse Cookies!

If you don’t want to go the powder route, you could also bake the magnesium into low sugar horse cookies – it is heat resistant. Or make raw horse cookies from ground flax, shredded carrots, oats and some hemp oil and molasses to bind them together. The molasses would also disguise the taste of magnesium.

I don’t recommend spraying or rubbing magnesium oil on the horse, because it is very itchy as it dries.

Dose to Bowel Tolerance

Just like in humans, you will know quickly if you are giving too much magnesium: your horse’s stool will get mushy or runny. In that case, cut back on the dosage. Since different forms of magnesium have different absorption rates, dosing to bowel tolerance is the best way to measure how much to give.

Here’s what “dosing to bowel tolerance” looks like in reality: We have been dosing 3 different horses/different breeds with the NOW Foods pure Mag Oxide and I can tell you that the Registered Quarter Horse hits bowel tolerance at just under 1 tsp. (2500 mg) as does the Arab/Andalusian cross. The purebred Andalusian does well on a rounded teaspoon. (~ 3300 mg), but any more than that and her stool is falling apart on the manure fork, and at 1 and 3/4 tsp. (5,000 mg) she’s got runny/mushy poop.

So although Getty’s recommendation is for 5,000 mg per horse, depending on your horse’s diet and unique body, you would need to adjust for the ideal amount for your horse.

Keep An Eye on Calcium Levels Too

The only consideration when supplementing with magnesium for horses, is to make sure that calcium levels are higher than magnesium. This is the reverse of the necessary ratio for humans. In humans, magnesium should be at a 2:1 ratio with calcium. But for horses, the ratio is reversed with calcium 2:1 to magnesium. However, Dr. Getty says that if the horse is eating hay or on pasture, then the calcium from hay or grass is likely sufficient to supplement with magnesium at the recommended dosage.

Having done a lot of research into the importance of magnesium for humans, I suspect that its importance for equines is similarly underestimated and misunderstood. And this is probably the reason magnesium levels are so pitifully low in feed and combination minerals supplements. Until equine supplement manufacturers catch on, this is one very important mineral that you’ll need to dose individually (in addition to your regular feed or supplements).

Jini Patel Thompson is a natural health writer and Freedomite. She began riding at age 2 in Kenya, and got her first horse at age 8 in Alberta, and so continues a life-long journey and love affair with these amazing creatures.

Magnesium to Relax Equine Muscles and Nervousness

42 thoughts on “Magnesium to Relax Equine Muscles and Nervousness

  • June 4, 2015 at 8:39 pm
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    Hi Jini!! Great article. Mag oxide is so poorly absorbed by horses and humans. That’s probably why such a high dose is suggested. By using a more absorbable mag, along with companion nutrients, much less mag is needed to reach desired results. I really appreciate the shout-out for Black Diamond Cookies. I wanted to take this opportunity to let you and others know that I’m always available for questions. My email is listed above… Fire away!! 🙂 -Nicole

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  • June 4, 2015 at 11:38 pm
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    Hi Nicole,

    Yes, that’s true – mag oxide has the lowest absorption of all the forms (about 5%). I need to open up some magnesium carbonate capsules and taste them to see if that would work better!

    But I LOVE your Black Diamond cookies for those who want an easy solution – especially for a picky eater! Love the pics of your Paddock Paradise set-up on your site too – I’m looking forward to getting mine going… I may contact you for advice on that when the time comes!

    Thanks for all you’re doing to make life happier and healthier for these amazing beings. 🙂

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  • March 22, 2016 at 9:03 pm
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    How about using magnesium oil which is simply magnesium chloride flakes mixed with distilled water and then used topically? I understand the absorption is much better in a transdermal application than an oral one.

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    • March 27, 2016 at 4:39 pm
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      Yes that is correct, transdermal has a better uptake than oral. The only issue is that topical magnesium can be VERY itchy. But if you diluted it enough (test it on your own skin first) and then sprayed everywhere, you might be able to get enough into the horse. See how much you need to apply to hit bowel tolerance and then back off a bit from there.

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  • June 17, 2016 at 4:32 am
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    Hi Jini, thanks so much for this useful article. I wondered what your thoughts are on magnesium content in diatomaceous earth? We’ve been using it for parasite control and forage balancing.

    With regard to magnesium for humans, you are probably already aware that raw chocolate is the highest natural source of magnesium on the planet and is linked to the female craving for chocolate right before menstruation at which time our magnesium levels are lowest!

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    • June 17, 2016 at 8:33 am
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      Hey Nicola, a number of websites are listing the mineral content of diatomaceous earth as: “approximately 33% silicon, 19% calcium, 5% sodium, 3% magnesium 2% iron and many other trace minerals such as titanium, boron, manganese, copper and zirconium”

      However, I wouldn’t rely on it for parasite control:
      http://www.listentoyourhorse.com/clinical-studies-on-diatomaceous-earth-as-a-natural-de-wormer/

      And yes, I do know about the chocolate connection! However, due to the fact that roughly 40% of us are chronically deficient in Magnesium I think it’s important to supplement, here’s my take on it:
      http://blog.listentoyourgut.com/transdermal-and-nano-sized-magnesium/

      Thanks for stopping by and I love the name of your healing haven!

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      • June 17, 2016 at 9:43 am
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        I know the clinical studies haven’t proven efficacy but our worm egg counts have… significantly. From close to 3000 down to 575 in the space of one month of treatment. I wouldn’t expect a professional to recommend it without scientific backing but I’m trusting mother earth and many other people around the world using it for the same reasons.

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        • June 17, 2016 at 1:06 pm
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          I hear you Nicola – no one is a bigger proponent of natural than me! But unless we have a “control” horse or few who are not receiving DE, yet living in exactly the same circumstances, same food, etc. and being tested at the same times. We cannot claim that the worm egg reduction is due to the DE. FECs drop drastically for many reasons – the horse’s own immune system plays a big role, so do the seasons, as does the lifecycle of the worm, and so on. However, regardless of worming efficacy the DE is likely beneficial for a number of reasons, so no harm in continuing. And as I mention in my other post, even if you NEVER worm your horse, that is not necessarily a problem:

          http://www.listentoyourhorse.com/worming-horses-naturally-is-it-possible/

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          • August 9, 2018 at 3:20 pm
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            I have been feeding DE to my 2 horses for three years now and after running fecal exams for the third year my vet says they are parasite free. I am feeding less than an ounce. Spread the word. One note of caution I always combine with a wet feed as the powder can damage eyes.

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  • January 3, 2017 at 9:28 am
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    I’m a little confused… the NOW link shows Mg at 400mg per 1/4T so 1600mg per T, not 2800 as you state above. What am I missing?
    I’m seeking a less expensive alternative to a supplement I have my gelding on currently for Mg at 8grams/day costing us $60/month…

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    • January 13, 2017 at 10:39 am
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      Good catch, GK. I re-did the calculations for both products and the comparisons are now correct. Thanks!

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      • January 16, 2017 at 6:10 am
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        Thanks! I’ve ordered the NOW product to try when his current one runs out…Hoping for good results with less cost!

        here it is:  

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  • January 16, 2017 at 6:35 pm
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    Hi GK – am I missing something here… cause your horse looks in great condition! I would not call him overweight at all. Is it the photo?? Do you know what breed(s) he is? The top of his foreleg (the width of the bone) sure says “Draft” to me – maybe he is part Draft?

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    • January 16, 2017 at 6:49 pm
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      Oh his pictures are deceptive! He weighed 1000lb in August, probably hasn’t dropped much yet, though I have noticed him not quite as round lately other than our issues with saddle rolling!
      He is pure Arabian – built very round barreled and broad shouldered. He has some crest in his neck and a little extra fat on the ribs/rump we are working to lose!

      here it is:  

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  • January 16, 2017 at 7:13 pm
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    Oh, I see what you mean – not much left though, you’ve obviously done a great job getting him balanced thus far! He looks like a real character and I love his coloring. Man I LOVE this new picture upload function! Makes these exchanges so much more fun 🙂

    Have you noticed any clear markers or effects that you can attribute to the magnesium supplementation? Or is his progress more of a holistic process, with many factors contributing to his improvement?

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    • January 17, 2017 at 4:58 am
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      Thanks, he is a “goober” as we say… You can’t help but laugh at him sometimes!

      I would say we attacked a lot of things at once. He has a gone from pure (lush) pasture when I bought him in May to adding a ration balancer, biotin, and flax. His mane and tale improved immensely with that. I also keep up with worming per fecal counts.
      He has had chiro, massage, and just more recently a full osteopathic body session. I added the Mg in almost 3 months ago and have finally started noticing a softening of the crest in his neck. Now that we have saddle fit issues under control again he goes back into more consistent riding and I expect to see even more change – plus with it being winter I think the extra calories burnt keeping warm are helping! (turnout 24/7 and only blanketed in the worst of things)

      Just as a note on the upload – it says a 10MB limit, but I had to re-save pictures as smaller files, like under 1MB to upload (normal size is only 2-4 MB)

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      • January 18, 2017 at 10:58 am
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        Very interesting and thanks for giving us all the details – what a wonderful horse steward you are! Everything you’re doing is really great and I’m wondering if Magnesium is as crucial for horses as it is for humans – it might be one of those “try first” substances… and luckily it’s so affordable. And thanks for the pic upload info – I’m looking into that now.

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  • February 9, 2017 at 9:38 pm
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    Hi Jini ….

    In your comment on June 4 you wrote “mag oxide has the lowest absorption of all the forms (about 5%)”. On Dr. Getty’s website the comparison chart seems to indicate that mag oxide is best because “Readily absorbed and most concentrated.” Hmmmm…. I’m confused! Can you clarify?

    http://gettyequinenutrition.biz/Library/SourcesofMagesiumIncludingWholeFoods.htm

    I’m considering a product by Uckele called Magnesium Oxide 58.
    http://equine.uckele.com/magnesium-oxide-58.html

    Thanks for any light you can shed on this!

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    • February 9, 2017 at 9:44 pm
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      Hi KB,

      It looks like Dr. Getty’s classified the supplement form (mg oxide, citrate, sulfate) as Inorganic source.

      And then the chelated forms (bound to an amino acid) as Whole food source.

      Alright. So – as someone who formulates health supplements – her terminology is not quite correct, but I think she is striving to put things in terms the average horse owner can understand.

      So now that I’m tracking with her definitions/classifications… When you purchase a magnesium supplement, you are not purchasing a product that is made of 100% magnesium. Magnesium is usually in a base or carrier substrate of some kind. So Getty’s Percent Magnesium column is referring to how much actual magnesium is present in a supplement labeled “Magnesium Citrate” for example.

      However, I have a Certificate of Analysis here from one of my vendors (for Magnesium Citrate) and the amount of actual magnesium is 15.44% – the rest is the carrier substance.

      So you can use her Percent Magnesium column as a guide, but if you can, check the supplement bottle to see if they provide that information. For example, this is what I did when I calculated the actual cost of the 2 forms of magnesium in my post above – you’ll note that even though the gross amount (1 teaspoon) is the same, due to the percentage of magnesium in each powder, the amount of actual magnesium differs.

      THEN you have to adjust for absorption rates. So in my example, even though there is 1600 mg of Mag Oxide per teaspoon, if absorption is only 5-9%, then it will be actually be cheaper to buy the Mag Carbonate, because you will need to feed less of it.

      This article gives a REALLY good explanation of how it all works and the actual absorption rates of the different forms of magnesium:

      http://www.clinicians.co.nz/which-magnesium-is-the-best/

      I’m not sure why Dr. Getty is saying the Magnesium Oxide is at a 50% absorption rate as that contradicts everything I’ve ever seen. Maybe email her and ask her to provide her research on that figure. Let us know if you find out!

      Reply
  • February 27, 2017 at 7:19 am
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    Hi I have a head strong gelding, I used another supplement with magnesium and other ingredients but am finding it very expensive to give on a regular basis. I have noticed a dramatic difference in feeding the supplement in his ability to stay calm and not be flighty. I am wondering if I can just feed the feed grade magnesium oxide on a daily basis and how much to feed. He weighs around 900 lbs. Thanks

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    • February 28, 2017 at 2:00 pm
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      You can either follow Dr. Getty’s guidelines for dosage, or, just feed to bowel tolerance. When you see his poo start to get mushy, that’s the maximum dosage, so feed a little under that so his bowel movements are normal.

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  • March 25, 2017 at 10:45 am
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    Thanks for this Jini, I am going to get the magnesium for my horses and other supplements you are mentioning on the other post. I have been so unhappy looking for horse supplements, they are all so “junky”! Oh, and the cookie link does not work anymore. Any ideas about that?
    Thanks!!

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    • March 25, 2017 at 11:06 am
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      Hmmm seems her entire site has gone AWOL! You could also make magnesium horse cookies yourself – it is heat resistant so can be baked in. I’ve put some suggestions in the post. If you find a good recipe, please share it with us!

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  • May 8, 2017 at 12:37 pm
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    “But, if I go buy the bulk magnesium oxide from my local feed store, the package says it contains 48% magnesium oxide… and the remaining 52%? Unaccounted for! ”

    Not “unaccounted for”.
    At least, not at the level you think.
    Magnesuim oxide is ~60% Mg and 40% O by weight.
    So the 48% cited on the label you looked at means that 48% of the stuff in the bag was magnesium. A proportional amount of the remainder would be oxygen(32% in this case), and the rest (20% here) would be “unknown”. Depends on the producer and the source.
    I’m a bit surprised the Mg content is that low–around here, feed grade MgO is typically 56% magnesium.

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    • May 8, 2017 at 3:47 pm
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      No, unfortunately that is not what the label means. First of all, magnesium (and any mineral) needs to be in some kind of form (bound or chelated to another substance) – e.g. magnesium oxide, magnesium citrate, magnesium bisglycinate etc. If there is only pure magnesium, then it would be atom-sized magnesium, which is a nano-particle. Likewise, if it contained pure oxygen, then oxygen in it’s natural state is a gas/vapor – so it would not be part of a powdered mix in a bag. I know this is confusing, but as I have been formulating health supplements for over a decade (which must all meet FDA and Health Canada approval and labeling requirements) I have a better grasp on the science/terminology than most. Hope that helps!

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  • May 8, 2017 at 7:08 pm
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    It is most certainly what it means. It *is* magnesium oxide, and magnesium oxide is approximately 60% magnesium and 40% oxygen by weight. The percentage reflects the proportion of magnesium by weight contained in mag oxide. It can be easily calculated by anyone with access to the periodic table.

    Here’s an example of a typical bag of mag oxide:
    https://www.hiprofeeds.com/products/magnesium-oxide-56

    So if you had a bag of magnesium oxide that had a label stating it was 48%, it’s referring to the magnesium content.

    With all due respect, I’m not the confused one here.

    I have a bit of background in the sciences and in horses, as well, including many years of teaching equine nutrition.

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  • May 8, 2017 at 7:32 pm
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    That’s why they put a label on the bag and call it “Guaranteed analysis”.

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  • May 8, 2017 at 7:34 pm
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    Oh, and I’m fully aware of what MgO is.
    I’ve taken inorganic chemistry, organic chemistry, and biochemistry, and have a protein chemist with a PhD in biochemistry on retainer.

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  • May 8, 2017 at 8:18 pm
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    I think we’re crossing wires here… and perhaps feed-grade supplements are labeled differently from human supplements? I’ll give you an example. Here’s a CofA for Vitamin A (acetate). If this appears on a supplement label it will ONLY list the amount of Vit. A present. But as you can see from the supplier Certificate of Analysis, this product also contains acacia gum, maltodextrin and DL-Alpha-Tocopherol – none of which would appear on any label, nor are they required by law to appear.

    So I’m assuming that when I buy a bulk bin bag of MgO labeled “Magnesium Oxide – 48%” I’m assuming it means that 48% of the total content is MgO – is this not a bonded/reacted substance? What am I missing here? In my world, the labeling is for the TOTAL amount of the listed substance (MgO)

    Oh here’s another thing – and again, perhaps this is simply a difference in labeling laws between human and animal supplements?? – If I have a Chromium Citrate, for example, which is at only 2.5% of the total mass (the rest is cellulose). Then the vendor is going to list that on the supplement label as X mcg of Chromium Citrate – the vendor is not going to tell me how much cellulose is in the product. So, in that case, it would not mean that 2.5% is the chromium element and the remaining 97.5% is citrate. It means that 2.5% is Chromium Citrate. It is from this that I’m extrapolating that the feed-grade supplement is labeled accordingly and the 48% is Magnesium Oxide (not just atomic magnesium).

    Do you get what I mean? If I’m missing the boat here, please enlighten me… and perhaps this is just a difference in labeling regulations?

    here it is:  

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  • May 9, 2017 at 8:08 am
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    “perhaps feed-grade supplements are labeled differently from human supplements?”

    Indeed they are.

    According to AAFCO (American Assoc. of Feed Control Officials), this is the required labelling for magnesium oxide:

    “Magnesium oxide (IFN 6-02-756 Magnesium oxide) is the oxide of magnesium
    generally expressed as MgO. Minimum magnesium (Mg) content must be specified.”

    “So I’m assuming that when I buy a bulk bin bag of MgO labeled “Magnesium Oxide – 48%” I’m assuming it means that 48% of the total content is MgO – is this not a bonded/reacted substance? ”

    Since the nutrient of interest is the mineral magnesium only, the amount of magnesium in the bag is the only thing that AAFCO is interested in. So your 48% MgO would be 48% magnesium by weight. The oxygen is irrelevant here.

    “What am I missing here? In my world, the labeling is for the TOTAL amount of the listed substance (MgO)”

    This is not your world, then. Different–probably because listing *only* the nutrient in question simplifies the work needed to calculate the amount of the stuff needed to provide a given amount of magnesium. Again, the oxygen portion of the compound is irrelevant for our purposes.

    Here’s a spec sheet from a bulk supplier—note that the product is referred to as “54% Magnesium oxide”, which is in reference to the magnesium content, even though the datasheet shows that the compound is 93% pure MgO overall.

    http://www.feedproducts.net/download/datasheet/Spec-FPS-Magnesium-Oxide-54.pdf

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    • May 9, 2017 at 10:24 am
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      Ah! Mystery solved. Who knew the labeling requirements would be so different? Thanks so much for spec sheet though – that makes it crystal clear. I will amend the blog post accordingly and add in this info for new readers as well. Thanks so much for chiming in here and lending your expertise! It was a bit of a back-and-forth but we got there in the end 🙂

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  • May 12, 2017 at 9:54 am
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    Please note on the NOW Product they changed! When I ordered it I received bottles that only has 240mg of MG per 1/4 teaspoon not 400mg as pictured on Amazon – so, you have to almost double your numbers! At that rate, I’m not sure it works out any cheaper than the specifically horse oriented ones like from Getty Nutrition at $38 for 5lbs worth…

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    • May 12, 2017 at 4:58 pm
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      Hi GK – did you click the link in the post here? Because when I clicked it, the product description photos still showed 400 mg per 1/4 tsp… OR are they promising one product and then you received another?

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      • May 12, 2017 at 5:29 pm
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        Yes, I did use the link here and complained to Amazon that what I got was different. Apparently they still haven’t updated their description of the product – Amazon of course refunded me for it as it isn’t as advertised!

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        • May 12, 2017 at 10:27 pm
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          Oh I hate that about Amazon – but thanks so much for letting us know! Okay, I’ve changed the link in the post to link to Dr. Getty’s magnesium oxide – free shipping and you can’t beat the price!

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          • May 13, 2017 at 11:43 am
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            I know right! At least Amazon makes it right, and I still used it – just didn’t reorder!
            I get several items from Dr. Getty’s site now…it makes for me having to make my own supplement packs for the Barn Manager to feed but that is easy enough for such huge savings over real smartpacks!

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  • February 28, 2018 at 7:31 pm
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    I see Chelated Magnesium mentioned, but never really answers my question. Is the Chelated Magnesium a good source? I would think it would be the best for absorption purposes, but I’m not expert. HELP!!!

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    • February 28, 2018 at 11:55 pm
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      Chelated magnesium is where the magnesium is bound to an amino acid – which is thought to improve absorption in humans (versus other types of magnesium). Although I don’t believe there’s any hard science (clinical trials) to justify this claim – where they have tested chelated magnesium against other forms. I’m not aware of any equine studies on chelated minerals – perhaps your vet might know.

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  • November 17, 2018 at 4:57 pm
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    So the bulk bag of magnesium from the feed store. How much do we feed for 1000 pound horse per day. She is Pssm 1..I have been giving 2 tablespoons a day.. for quite sometime. Is this too much.

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    • November 18, 2018 at 1:17 am
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      Just follow the instructions in the blog post, then, you can try increasing until your horse hits “bowel tolerance.” Basically, you want to give the highest dose she will tolerate, at least for 3 months or until deficiencies are resolved. If you’re not sure what the dosage is for the product you buy (i.e. how many mg per teaspoon) then ask your feedstore to get you that information. Hope that helps.

      Reply

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