Magnesium - the myths and reality

[SEL]

That's really interesting Purbee - thank you

I just went and dug out the soil analysis I had done for my summer field (currently more of a marsh than a field) and it was high in magnesium. My Appy lost weight and her enlarged thyroid vanished within 2 weeks of moving to these fields despite the fact that I didn't restrict her and they came off soaked hay. I've always known she's needed magnesium supplementing but I imagine the uptake from grass is very different to the uptake from a supplement in her feed.

 

[PurBee]

That's really interesting Purbee - thank you

I just went and dug out the soil analysis I had done for my summer field (currently more of a marsh than a field) and it was high in magnesium. My Appy lost weight and her enlarged thyroid vanished within 2 weeks of moving to these fields despite the fact that I didn't restrict her and they came off soaked hay. I've always known she's needed magnesium supplementing but I imagine the uptake from grass is very different to the uptake from a supplement in her feed.

Thats interesting to hear Sel, what region are you in?, as sometimes it can be a small valley of fields found to have a peak or deficiency of a crucial mineral, or sometimes it can just be one field. If a field is at the bottom of a slope, with no drains in between, silt (inorganic minerals) over time, can get washed down to lower fields, essentially helping them to be more fertile than higher fields.
The magnesium in grass/plants is in an easier to digest form than inorganic minerals. The plants consume inorganic minerals and convert them to organic electro minerals for mammals to absorb easier.
Supplements often contain inorganic mineral powders, so rarely 100% of the dose is absorbed, but that’s not to say none is absorbed - mag ox is about 50%. While we have soils of varying mineral amounts, we have no choice but to add some of the shortfall in their diet in the form of inorganic minerals.
(There is the option of buying chelated and suspended colloids in water of minerals, but they are eye-wateringly expensive to buy for horse doses, and even then not 100% is absorbed.)
Whereas if mag ox is added to fields (at the right time of year - spring) almost 100% would be absorbed by plants, and almost 100% of the mag in the plants would be absorbed by grazing animals.
Freshest is best.

Your appy benefits on your field are great to hear. When i read years ago that magnesium has so far been identified with @ 300 processes in the body, many of them very vital, i appreciated how much it is an essential mineral.
My experience with magnesium added to the soil really opened my eyes to soil mineral balanced health. My 2 were so good on it, not spooky despite free range grazing, eat as much as they want. The mares weight, normally prone to fattiness in summer, wasnt an issue.

 

[SEL]

Thats interesting to hear Sel, what region are you in?, as sometimes it can be a small valley of fields found to have a peak or deficiency of a crucial mineral, or sometimes it can just be one field. If a field is at the bottom of a slope, with no drains in between, silt (inorganic minerals) over time, can get washed down to lower fields, essentially helping them to be more fertile than higher fields.
The magnesium in grass/plants is in an easier to digest form than inorganic minerals. The plants consume inorganic minerals and convert them to organic electro minerals for mammals to absorb easier.
Supplements often contain inorganic mineral powders, so rarely 100% of the dose is absorbed, but that’s not to say none is absorbed - mag ox is about 50%. While we have soils of varying mineral amounts, we have no choice but to add some of the shortfall in their diet in the form of inorganic minerals.
(There is the option of buying chelated and suspended colloids in water of minerals, but they are eye-wateringly expensive to buy for horse doses, and even then not 100% is absorbed.)
Whereas if mag ox is added to fields (at the right time of year - spring) almost 100% would be absorbed by plants, and almost 100% of the mag in the plants would be absorbed by grazing animals.
Freshest is best.

Your appy benefits on your field are great to hear. When i read years ago that magnesium has so far been identified with @ 300 processes in the body, many of them very vital, i appreciated how much it is an essential mineral.
My experience with magnesium added to the soil really opened my eyes to soil mineral balanced health. My 2 were so good on it, not spooky despite free range grazing, eat as much as they want. The mares weight, normally prone to fattiness in summer, wasnt an issue.

In Bucks. That particular field has a very high water table so was the only one with any decent growth in last year's drought. It leads down to a stream and I suspect the underground spring (there is an old well) fills up from all the surrounding land so no doubt brings nutrients with it. The soil report came back as needing sulphur and everything was an odd yellowy colour when I bought the fields which I believe can be sulphur deficiency. It did look a lot better after I'd applied sulphur granules.

Very low in copper and selenium in the area. Copper was highlighted on the report and selenium by a local farmer and agreed with the maps you can find online (except the link I had is broken). In desperate need of aeration once I can get machinery into it.

I was planning on testing two of the other fields this year., so it will be interesting to see if they have a different profile (only 7 acres in total but all the fields in the 7 acres have very different grass growing personalities)

Very over grazed when I bought it and the weather hasn't been kind in the last 18 months so slowly, slowly in terms of improvement.

 

[Fieldlife]

I thought it was fairly well accepted that most English soil and hence, grass and hay is typically short of magnesium, copper, zinc and selenium. (And also sodium relative to horse's needs).

Analysis is the only way to get a certain view on what precise deficiencies specific grass and hay has, but problematic as two neighbouring fields can have vastly different results. Whether grazing or hay fields. Hence there is an argument for relying on English soil averages.

I think it is common sense to feed a supplement with added zinc, copper, magnesium and selenium in it. And to add salt (sodium) to all horses' diets. And vitamin E if grass limited in diet e.g. in mid winter.

If you are feeding supplementary hard feed as well as hay and grass, you look and see if the amounts you feed contain sufficient zinc, copper, magnesium and selenium before deciding if need to supplement further.

 

[PurBee]

HaHa, that is what they told me too!!!

I was not buying something that made her worse.

Really interesting PurBee, in fact I just ordered some Mag Ox for Rigs on the strength of your post.

I would only add calcium if I had a hard working sports horse who was consuming high energy grain feeds (phosphorus) and the hay/forage they got was ‘average’ calcium levels - then theres a case to argue more calcium may be needed (and also more mag) to balance out the fairly high phosphorus in the diet.

We should remember that almost all kidney stones formed in horses are calcium carbonate, so to feed excess calcium when we know thats the most on average abundant mineral in soils and forages, is asking for trouble later in the horses life, and kidney health.
Yet, there’s no study ive found where the stones are made of magnesium from all this ‘excess’ people are feeding to balance the diet.

A tip when adding any supplement. Disregard the daily dose initially - just give a quarter of the ideal daily dose for a few days, then half the dose for a few days, work up to the full dose over 7-14 days. This allows the body’s innate homeostasis to not be shocked by a sudden introduction of a new nutrient. Titrating the dose from small to large aids the body to slowly absorb what it needs.
That way you can allow the body to slowly accept and use the new supplement, you can observe changes, and stop at a dose where we notice they’re doing ok.

I often wonder with those who say their horse freaked-out on magnesium, how they dosed them. Because magnesium is essential for forming the body’s primary energy ATP molecule, a sudden intro of a recommended scoopful of magnesium, especially if the horse is deficient, may result in an energised animal. The owner could be used to a placid horse, because the horse doesnt have the physiological energy to be energetic. Im thinking more the placid cobs types prone to fattiness, but even a deficient warmblood could be called placid/plodder in a deficient state.
But there’s a vast difference between an calm, energised horse and a spooky horse, and i wonder if the energised horse is being experienced for the first time with full dose magnesium supplement, and it freaks owners out, so they immediately stop the dose too, thinking the nutrient is bad, rather than the sudden dose given.

The answer is to always dose supplements low dose slowly…bit by bit.

I’ve experienced both states in earlier years with my welsh/arab mixed pair. Sudden magnesium and theyre energised but still sensible. Sudden (unintended) switch to high sugar hay or haylage and theyre prone to be very energised.
They were both defined as spooky before mag supplementation. Placid, kinda dopey for arab types, but easily spooked/unpredictable.

Magnesium gives natural ATP energy and also relaxes the muscles and nervous system (aswell as loads of other essential bodily functions), so for it to be labelled as a ‘calmer’ is really an inaccurate marketing claim, as it does many things, and absolutely isnt just a ‘sedative’ mineral.

The ATP energy molecules it helps make are what enables the fat horses to lose weight (those types that get fat on fresh air especially) Without magnesium the body (liver) will shunt the calories from hay as storage ‘energy’ on the body as fat. If there’s not enough circulating magnesium thats the only option the liver has. What reserves of magnesium its pulling from bones, is used to keep the heart and muscles contracting and relaxing 24/7. That primary importance, in comparison to burning calories.
We know so well that with some horses we cant get the fat gone no matter how much soaked hay or low calorie feeds are given. Without magnesium its physically impossible for the body to make ATP energy molecules.
(This physiology applies to humans too with potential weight/energy issues)

My mare (half welsh, half arab) was getting just a mildly-heaped teaspoon that helped shift her fat pads. She needed just a bit more to keep her metabolism working better. She was on a balancer with a bit of mag in it too.
The gelding, much younger and definitely dopey yet spooky. So he was also showing deficiency symptoms but had enough bone reserves not to be struggling with fat at that young (3-5) young age.
Its better for them to have a small teaspoon dose than a huge dose, initially, unless you test your grass and hay for magnesium, and know they’ll need to be progressed to a higher dose.

Many supplement companies say start-off with full dose, which can induce some rebound symptoms, as body homeostasis is knocked off balance temporarily by the new dietary supplement.

Im not saying magnesium is a panacea for all horses issues. Just highlighting it is an essential mineral that lays the foundation of dietary health , for all mammals really, and has been shown on average to be low in soils and forage, so deserves our consideration, especially when dealing with fatty horses, or endocrine issues and genuine docile/spook easy horses. Strip diet back to consider calcium/phosphorus/magnesium/sodium balance ratios in their diet.

Remember to dose small and slow and work the dose-up slowly.

 

[Fieldlife]

I would only add calcium if I had a hard working sports horse who was consuming high energy grain feeds (phosphorus) and the hay/forage they got was ‘average’ calcium levels - then theres a case to argue more calcium may be needed (and also more mag) to balance out the fairly high phosphorus in the diet.

Remember to dose small and slow and work the dose-up slowly.

Yes, I currently supplement calcium as I am feeding micronised linseed, Copra in fairly large amounts, and rolled oats in moderate amounts, all high phosphorus and low calcium. I have taken advice on the amount to supplement.

 

[PurBee]

In Bucks. That particular field has a very high water table so was the only one with any decent growth in last year's drought. It leads down to a stream and I suspect the underground spring (there is an old well) fills up from all the surrounding land so no doubt brings nutrients with it. The soil report came back as needing sulphur and everything was an odd yellowy colour when I bought the fields which I believe can be sulphur deficiency. It did look a lot better after I'd applied sulphur granules.

Very low in copper and selenium in the area. Copper was highlighted on the report and selenium by a local farmer and agreed with the maps you can find online (except the link I had is broken). In desperate need of aeration once I can get machinery into it.

I was planning on testing two of the other fields this year., so it will be interesting to see if they have a different profile (only 7 acres in total but all the fields in the 7 acres have very different grass growing personalities)

Very over grazed when I bought it and the weather hasn't been kind in the last 18 months so slowly, slowly in terms of improvement.

Youre doing the right thing to get to know your land. Its so interesting you have the underground spring in that field, and agree with you that could be bringing minerals with it into the field.

Selenium is mostly deficient, although theres a region mid-ireland with known high selenium soils, so it is worth all horse owners checking the online soil maps of an area to get an idea of soil types our horses are grazing on.

Individual testing of fields, as youre doing, is the best way to go, and you’ll benefit hugely from knowing in-depth your own land, and adjusting your land and/or their diet to balance their diet, and see the results.

 

[PurBee]

Yes, I currently supplement calcium as I am feeding micronised linseed, Copra in fairly large amounts, and rolled oats in moderate amounts, all high phosphorus and low calcium. I have taken advice on the amount to supplement.

I read an article years ago about the old way of giving beet and oats to working horses turned out to be nutritionally balanced as the beet is high in calcium, and the grains phosphorus. We didnt have science back then to know.
Before marketing of gazillions of products came to confuse and confound, we seemed to be automatically in tune with giving a balanced diet, like you knew calcium would be needed.

 

[criso]

I feed copra and linseed but don't supplement calcium however i don't add phosphorus to the mineral mix which was in the recommendation of minerals to feed and i don't buy an off the peg balancer which would include phosphorus.

Interestingly another horse on the yard that had blood tests for different reasons came up as deficient in phosphorus. Different feed but on the same grazing and forage.

 

[Rowreach]

I read an article years ago about the old way of giving beet and oats to working horses turned out to be nutritionally balanced as the beet is high in calcium, and the grains phosphorus. We didnt have science back then to know.
Before marketing of gazillions of products came to confuse and confound, we seemed to be automatically in tune with giving a balanced diet, like you knew calcium would be needed.

I'm old school when it comes to feeding and still feed straights, and yes, it was an art not a science back then, but when the science bit took over it became clear that accidentally horse people were balancing feeds pretty well. I learnt about feeding from a chap whose family had been horse dealers/breeders/livery men for generations, and the ingrained knowledge that was passed down was phenomenal.

 

[paddy555]

My annoyance on the PSSM forums is Malcolm (owner Equifeast) is allowed to comment and shouts down anyone who disagrees with his interpretation of magnesium as a potentially dangerous calmer.

he hasn't changed over the years then I remember him from another barefoot group many years ago. We had the same arrogance and shouting down even back then.

 

[Peglo]

@PurBee do you think it’s worth giving magnesium if your pony is overweight still at this time of year when the grass is so crap? Or would you test soil before trying it?

 

[Nudibranch]

I think some of Equifeast's success comes from the fact that it's human nature to oversimplify cause and effect. There's rarely a magic bullet, not even magnesium, which I find does nothing for my borderline EMS Fell's fat pads. Or tendency to grow flat feet. However if my PSSM mare doesn't get her balancer, she has no energy at all and eventually ties up.

Quite apart from the fact I wouldn't touch Equifeast with a barge pole due to the poor attitude I've seen on various groups, nothing he/they have ever said has ever convinced me that their views on magnesium and calcium are accurate.

 

[PurBee]

@PurBee do you think it’s worth giving magnesium if your pony is overweight still at this time of year when the grass is so crap? Or would you test soil before trying it?

Yes, moreso when grass/fresh green plant intake is very minimal, and if not already on a balancer with magnesium. Start low dose half teaspoon for a few days, then up it to full teaspoon. There’s margin of error allowable as it is so easily excreted, but its far easier to just ease them onto it and monitor progress.

There could be a difference between minerals in the soil and whats in the grass. Factors like PH of soil and the soil bacteria population health determine how well the grass can uptake the minerals in soil. The difference between the 2 on fairly healthy ph balanced soils arent wildly different - but its worth bearing in mind when land is overly alkaline (chalk soils) or acidic (peaty), and land that annually receives herbicide sprays or acidic NPK fertilisers as they affect soil bacteria, there is therefore likely a difference between soil values and grass values.

Soil bacteria are like the ‘gut biome’ of mammals - if theyre not in balance or healthy, they cannot do their job so well of delivering nutrients into the plants growing in the soil. Just like the gut biome when out of balance with gut bacteria wont absorb nutrition so well.
Farming methods are moving into ‘biological farming’ - with more a focus on soil bacteria health, to improve crop quality and yield, alongside balancing mineral depletions.
Mammalian health works on similar principles - have a healthy gut biome to make the most of absorbing nutritious food.

The ideal route would be 3 mineral profile tests - A soil test for major minerals (and micro if youre willing to invest in finding out the whole array of minerals - worth doing for landowners and folk who’s horse is happily sited on longterm livery with their own field) A mineral test of grass growing in the grazing field, and a mineral test of their usual winter hay/lage supply.
With those results we can gather the amount in grams or milligrams of minerals the horse intake is. There’s average grass intake per hour data online to help work-out grass intake while grazing, i forget off-hand the figures right now.
That‘s as precise as we can get to really knowing what their intake is.

If there is a wild difference between soil and grass samples - we know we need to help the soil become better balanced so the plants can uptake the minerals the soil test has revealed exists - via PH balancing and soil bacteria.

If a person doesnt want to go the whole hog of 3 tests, and wants to still have an accurate idea, the best route would be to test the forage the horse eats the most of - for those out grazing 24/7, that would be the grass - for those with majority hay/lage diets, test that. That 1 test gives results to work from and is more accurate than using regional averages.


If someone can’t test, the soil observatory website is excellent for soil data and gives fairly detailed soil maps of regions. I’ll link them below. Go through the guide steps to learn to use the map - they have data on ALL minerals, nutrients, carbon - its very good.

Here’s a pic of their magnesium data for england and wales (unsure why there’s no scotland or NI though)






As you can see, the red regions show highest magnesium deposits, 1-5% = 10g-50g per kg of topsoil (nb. Not per kilo of grass). The blue/turquoise areas showing lower deposits 1g - 5g per kilo of soil.

The map is accessed from here: http://www.ukso.org/
(Click on ‘UKSO map viewer’ - follow the guide and add ‘map layers’ to see individual minerals)

Here’s topsoil PH averages (showing majority acidic, and why lime is used so widely to help raise ph to preferred 6.5 for soil mineral uptake, side-effect = forages to be on average high in calcium.)




Compare the 2 and see why the acidic soils of wales for instance, cannot uptake the high magnesium shown in the soil, in the previous chart, without raising the PH with calcium Lime.

This chart below shows what PH is needed for soils to give available minerals to plants, and shows why landowners aim for a PH of 6-7 to help most minerals be uptaken by grass/plants:


1 The pH scale, showing the effects of soil acidity and alkalinity on the availability of different minerals. Colours indicate availability of the elements. Green: available; yellow: low availability; red: not availabile