The name ‘Vitamin K’ refers to a group of fat soluble vitamins that include:
Vitamin K1 (phylloquinone): found in fresh green plants
Vitamin K2 (menaquinone): produced by bacteria. There are 15 different menaquinones
Vitamin K3 (menadione): synthetic vitamin K
What does vitamin K do?
Vitamin K is required for many functions in the body. The most important of these are:
Activation of blood clotting mechanisms
Maintaining vascular health; and
Healthy bone metabolism
How much vitamin K does a horse need?
The true requirement for vitamin K in horses is still unknown. Primary vitamin K deficiency (i.e. nutritional deficiency not caused by a vitamin K antagonist) has never been recorded in a horse.
Published information suggests that the absorption of vitamin K from fresh forages and absorption of vitamin K produced by bacteria in the gut is enough to meet requirement. However, recent studies have called into question the ability of a horse to absorb bacterial derived vitamin K2 from the hindgut1. Still, there are many bacteria in a horse’s small intestine and vitamin K is definitely able to be absorbed from there.
However, horses in stable conditions without access to fresh green forage may not receive optimal amounts of vitamin K in their diets. In these situations, some supplementation may be required.
What form of vitamin K is best?
There has been some debate in recent times regarding which form of vitamin K is best to supplement with. In horses, it appears that most forms of vitamin K are suitable for supplementation.
A study in horses published in the Journal of Animal Science (Terachi et al 2011)2 found that supplementation with Vitamin K3 (the form most commonly used in horse feeds) was the most effective at increasing blood concentrations of the biologically active menaquinone, MK-4.
A more recent study3 has suggested that vitamin K3 is not converted to MK-4. However this study used a single dose of vitamin K3, with blood samples only taken for 8 hours post-dosing. This is in contrast to the Terachi et al. study which supplemented horses for 7 days and found the highest levels of MK-4 in the vitamin K3 supplemented horses. It is likely that in the study of Skinner et al, the single dose of Vitamin K3 and the short time-frame for blood sampling may not have allowed enough substrate or time for conversion to MK4 to occur.
Vitamin K3 has been demonstrated to be converted to biologically active MK-4 in multiple animal species and it would appear horses are no exception.
Skinner JE, Cawdell-Smith AJ, Regtop HL, et al. 59 Extent of vitamin K absorption from the equine hindgut. Journal of Equine Veterinary Science;35:409.
Terachi T, Inoue Y, Ashihara N, et al. Plasma vitamin K concentration in horses supplemented with several vitamin K homologs. J Anim Sci 2011;89:1056-1061.
Skinner JE, Cawdell-Smith AJ, Biffen JR, et al. 11 Intestinal absorption of different vitamin K compounds in the horse. Journal of Equine Veterinary Science;35:387.
Meet The Author: Dr Nerida McGilchrist
Dr Nerida McGilchrist is FeedXL’s co-founder and equine nutrition specialist. She holds a degree in Rural Science, a doctorate degree in equine nutrition and nearly 20 years of full time, on the ground experience in feeding all types of horses. To learn more about Nerida and to ‘meet’ the rest of the FeedXL team, check out our About Us page here.
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We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
I don’t know if you have noticed, but there are LOTS of different electrolyte supplements on the market! Pastes, powders, liquids – and they are all so different… making it really hard to know which ones are best.
The job of an electrolyte supplement is to replace the electrolytes lost in your horse’s sweat… namely sodium, chloride and potassium (the three major ones) as well as magnesium and calcium.
Quick Tip: Forages are usually high in potassium. So when your horse is being fed a forage based diet, there is normally plenty of potassium in the diet to meet requirements during normal training periods. Which means the two main electrolytes your horse needs added to the diet are sodium and chloride. And together, these electrolytes are ordinary table salt… so topping up electrolytes is often as simple and inexpensive as adding salt to your horse’s diet!
For an electrolyte to do a good job of replacing the electrolyte minerals your horse loses when sweating, it should be at least 80% ‘salts’ and 20% or less glucose or other base or filler.
Specifically, these high quality products should be 20 – 25% sodium, 43 – 48% chloride, 10 – 12% potassium and also have smaller amounts of magnesium and calcium (normally 1 to 2%).
If you put one of these high quality products into FeedXL, for a 450 kg (990 lb) horse in very heavy work, at a dose of 60 grams per day, this is how it should look (with JUST it in the diet):
High Quality Electrolyte
This product is 22.5% sodium, 45.1% chloride, 12.1% potassium, 1% magnesium and 1.5% calcium.
To give you a comparison, here is another product, also added in FeedXL at a 60 gram dose for a 450 kg (990 lb) horse in Very Heavy Work … look how much less mineral you are getting at the same dose rate!
Low Quality Electrolyte
If the mineral levels are much lower like this, you’re probably paying a lot for a lot of filler and it might be time to consider a new supplement!
It can be a little tricky to read labels because everyone presents their label information a little differently (just to keep us on our toes!)… so if you want to check how good your electrolyte is, create a diet in FeedXL like this, for a 450 kg (990 lb) horse in Very Heavy Work, add 60 grams of your chosen electrolyte and see how it compares to these ones… the one at the top being good, the one at the bottom being a waste of money!
We hope that helps you to find the best electrolyte supplements! If you haven’t yet got started with FeedXL you can join us here.
P.S. Be really careful not to overfeed salt and electrolytes because they will make your horse’s feed taste yuk and your horse will stop eating. If your horse is not eating well, try reducing or even for a short period removing any salt or electrolyte from the feed and see if this helps. For more on keeping your horse eating, you can read this post.
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
“What symptoms would I see if my horse was mineral deficient?” ‘Anita’ asks me.
My answer…
“That’s a really good question”… the actual answer is the reason why so many of us don’t have ‘problems’ with our horses, we have ‘disasters’!
One of the things I love about being out and about at horse events is having real conversations with ‘real’ horse people about nutrition. I can sometimes forget that what is obvious to me is often not so obvious to others. So these types of questions really make me stop and focus on things from YOUR perspective.
Anita’s question was particularly brilliant because it highlights one of the HUGE issues in horse nutrition. And that is that ‘chronic long-term mineral deficiencies’ tend to go UNNOTICED until something truly goes horribly wrong.
The best analogy I can give you is it is like white ants… often the presence of white ants goes unnoticed until they have done so much damage to the structure of a building that things literally start to fall apart. Once you can SEE the damage, the issue is serious.
It’s like this with minerals (and vitamins) for horses. Once you can SEE a mineral deficiency, you can be sure that issue has been there for a long time and that the damage is now extensive.
Which means…
Just because you CAN’T SEE a mineral deficiency doesn’t mean one doesn’t exist.
And in fact if you are not supplementing your horse correctly, either with carefully chosen fortified feeds or vitamin/minerals supplements I would say with 99.9% certainty that your horse will be deficient in something that will eventually cause a health issue.
And here is the thing… all of these nutrition related deficiency issues are so easily avoided. Instead of spending several months (and often several thousand dollars) fixing the problems caused by deficiency… you can just prevent the deficiency and therefore prevent the issue.
Let me answer Anita’s question a bit more first, and then I’ll come back to how you can prevent the problems!
Here are some symptoms of mineral (and vitamin) deficiency…
And remember these are symptoms of LONG TERM deficiency, they tend to take several months to several years to show up… listed in no particular order:
Dull coat that lacks shine and richness of colour
Cracked, weak hooves-Joints that start to deteriorate at a young age
Poor immune response, taking a long time to recover from immune challenges
Changes in behaviour, often toward more anxious, spooky behaviour
Loss of muscle or inability to gain muscle
Weight loss or inability to gain weight
Low energy or reaching fatigue earlier than they should for their level of fitness
Gut issues, including poor digestion, poor absorption and an increased risk of gastric ulcers
Uterine artery rupture in foaling mares
Flexure limb deformity and OCD in foals and young horses
Stillbirths
Broken bones including legs, ribs, pelvis (unfortunately often the first symptom that is recognised in chronically calcium deficient horses)
This list could go on (and on, and on) but this will cover many of the issues many of you will see.
Unfortunately we also often try to treat the symptom before we treat the underlying cause. So good nutrition must (ALWAYS) go hand in hand with any treatments given to these horses. For example it’s virtually no use using a joint supplement when a diet is chronically copper and zinc deficient.
So I guess what I really want to convey here is that EVERY horse’s diet, almost without exception, needs some sort of vitamin and mineral support. And if they don’t receive that support, one (if you are lucky) or many of these issues will start to show in your horse.
And this is where FeedXL comes in… FeedXL helps you figure out exactly which vitamins and minerals are missing from the diet, and exactly which feeds or supplements (of the literally thousands of options you have) can be used to best meet those needs.
AND it stops us doing that thing where we overfeed or oversupplement Just. In. Case. Which at best leads to wasting money. At worst ends in equally disastrous vitamin or mineral toxicity.
The moral of the story? Just because you can’t see a problem doesn’t mean there isn’t a problem!
The sooner you look at your horse’s diet and fix any vitamin or mineral deficiencies, the better!
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
Question: What is the difference between a ration balancer and a vitamin/mineral supplement?
Watch the video below with FeedXL founder Dr Nerida Richards and SmartPak’s Dr Lydia Gray for the answer!
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
One of the pitfalls of feeding your horses without actually calculating what you are feeding is paranoia that maybe your horse isn’t getting enough of the most important nutrients. That maybe he is missing something and this is going to cause problems, or make him sick!
As a horse owner I am sure you experience this feeling of ‘maybe I should just add a little bit more…’ or ‘maybe I should add that supplement I was told about because it sounds important, I meet those requirements…’ or ‘I’ll just add this, and this (and this) and even this just to be sure I am covering everything!..’.
Problem is, feeding like that still doesn’t ensure you actually meet requirements. AND it is So. Very. Expensive!
How FeedXL Can Help
This is where FeedXL comes in… when you can feed with certainty because you know what you are feeding is meeting requirements you no longer need to add extras as a ‘just in case insurance’. With FeedXL you can see which requirements are met, and which may not be and adjust your diet accordingly.
This diet, for a mare named Smarty is the perfect example of this. Smarty’s owner has done a great job of putting together a diet that meet’s all of her requirements, but watch as I am able to completely remove one supplement PLUS reduce another supplement by 25%. Meaning every 4 days now she gets essentially a FREE dose… or put another way her supplement bucket will last 25% longer and cost her 25% less!
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
Looking from the outside, most of us as horse owners are pretty good at knowing how much feed our horse needs. We can see weight change which gives us a visual clue that the horse is not being fed enough (resulting in weight loss), or too much (resulting in weight gain).
What we can’t see are vitamin and mineral deficiencies. And the problem is, these often won’t show up as something we can see until they result in disaster… hooves falling apart, joints breaking down, an immune system so compromised that it can’t mount an effective immune response to a simple disease challenge.
Here is a classic example of a diet where the horse’s owner has done a truly great job in putting together a forage based diet with just enough of a single feed to maintain excellent condition! BUT the small amount of feed is not enough to meet the horse’s basic vitamin and mineral requirements.
Check the video out as I walk you through Lacey’s diet, which perfectly demonstrates what is happening in so many horse’s diets.
The good news is, with just a little bit of time spent in FeedXL and the addition of a single supplement, Lacey’s diet can be fully balanced to keep her healthy and happy in the long term!
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
Retained placenta… bad luck? Or is there more to it?
I am going to say there is definitely more to it. And if you look to the cattle industry they agree. And a lot of it comes down to one little mineral… SELENIUM!
I was recently at an Animal Nutrition conference at the University of New England. One of the speakers, Prof Michael Lee (University of Bristol) spoke about selenium. Here are a few photos I snapped of his slides:
Listed at the top of his list of symptoms of selenium deficiency in ruminants was retained placenta. And this is certainly what I see in horses too.
Almost the only time I see retained placenta as a widespread issue is on breeding farms that do not supplement pregnant mares.
The most recent case I dealt with was a farm with more than 100 standardbred broodmares. At the time of my first visit, the mares were not supplemented at all during pregnancy.
And retained placenta was occurring in 25 % of mares! 1 in every 4 mares were experiencing this potentially life threatening complication! Eek!!
I suggested that if they supplement with selenium (as part of an overall balancer pellet) that this shouldn’t be such an issue.
They decided they would experiment. And gave half the mares the balancer pellet. The other half they left unsupplemented.
The results were clear. The supplemented mares had one mare in 60 with retained placenta. That is less than 2%… a big reduction from 25%!
The unsupplemented mares had 2 retained placenta within the first 4 mares that foaled! This was enough to convince the farm that maybe we were onto something… so rather than keep going with the experiment they very quickly put all the mares on to the balancer pellet!
The interesting thing for me was that the incidence of retained placenta dropped almost immediately in this group of mares who were initially unsupplemented.
The nutrition of your pregnant mares is so important. This is just another reason you should pay close attention to mineral nutrition, especially because selenium is a mineral that is often low in forages and is therefore often deficient in diets.
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
A. No. And in fact it would be impossible to create a diet that met exactly 100% of your horse’s requirements for every nutrient shown here.
Q. So if not 100%, where should the nutrient levels be sitting? And what is normal? Because some of the amounts on this graph look really high?! Isn’t that dangerous???
A. Good question! And the answer is it depends on the nutrient. Forages, for example, contain high levels of some nutrients like iron and potassium. Because diets often have lots of forage, these nutrients will almost always be high in the diet.
BUT that doesn’t mean it is dangerous. In fact if you push a nutrient to a dangerous level, the bar for that nutrient will turn red, like this, to warn you that the nutrient is now at its ‘upper safe limit’ and needs to be reduced.
Q. OK, that’s good! So I know if I get a nutrient WAY too high FeedXL will warn me. BUT I still don’t know what is normal for all of the nutrients. Where should I expect to see them?
A. Yep, let me walk you through them all! Let’s use this graph and go through each nutrient.
Digestible Energy
This should sit, for most horses, somewhere between 90% and 105% of requirements. SOME horses have a lower or higher need for digestible energy (calories) so you may see the odd horse sitting below 90% or above 105%.
BUT, if you do enter a horse and the Digestible Energy is low or high and this does not correspond accurately with what you are seeing in your actual horse (meaning if the Digestible Energy is low in the diet you enter into FeedXL, normally you would expect to see weight loss. If it is high, normally you would expect to see weight gain) you MAY need to double check the information you have entered into FeedXL as this is a small red flag that something has not been entered right.
For example, if you have entered bodyweight that is too high, the Digestible Energy level will be low and vice versa. Or if you haven’t weighed your feeds and hay or classified your pasture correctly and you have entered amounts or qualities that are too low, then Digestible Energy will appear low and vice versa.
Quick Tip: If Digestible Energy in your horse’s diet is below 90% or above 105%, check that you have entered your horse’s bodyweight and weights of feed and forages correctly.
Crude Protein
The Crude Protein level in the diet should always be at or above 100%. And it is best to try to keep it less than 200%. For performance horses that are stabled and in work I like to try to keep Crude Protein below 160%, if I can… it is not always possible!
Depending on your forages, you may see Crude Protein go very high (well above 200%). Is this an issue? Generally it’s not, but there are some situations (like very hot, humid climates or when a horse is stabled) that it is not ideal. Sometimes, if it is your pasture for example that is high in protein, there is not a lot you can do about it. If the horse is stabled and fed hay, you should try to switch some of the higher protein forage (e.g. alfalfa/lucerne) for a lower protein forage (like a meadow/grass hay), to bring the overall amount of Crude Protein in the diet down.
Lysine is your indicator of protein quality (you can read about Protein Quality here https://feedxl.com/30-understanding-protein-quality/). Lysine should sit between 100% and 150%. If it is lower, it indicates your protein quality is low and your horse will struggle to do things like build muscle or make milk. In fact, when lysine is low in a diet you will likely see your horse losing muscle over his topline… it’s an important nutrient to get right in the diet.
Lysine may get quite high in some diets depending on the amount and source of crude protein. But if you follow the guidelines above for Crude Protein, you will find Lysine levels will adjust accordingly.
Calcium
Calcium should be at or above 100% in the diet and I like to keep it below 200%. Ideally, I like it sitting below 150% but depending on the feeds and forages being used, it is not always possible to achieve this. The amount in the diet shown here is lovely, more than the horse needs but well below 200%.
It is important with calcium to also check the calcium to phosphorus ratio in the diet (look in the Nutrient Table) to make sure it is within the right limits with phosphorus. And if you like to use the extra ratios, you can also check its ratio with magnesium, which as a guide, should be 3: 1 or less.
Phosphorus
Phosphorus should be at or above 90% and ideally below 150%. You may see some diets with high phosphorus ingredients like Rice Bran pushing phosphorus higher than this. If it is above 150%, be sure to check the calcium to phosphorus ratio on the nutrient table to make sure this is still balanced (there MUST be more calcium in a diet than phosphorus).
NOTE: You cannot calculate the diets calcium to phosphorus ratio off the numbers on the graph. It is always best to read the ratio off the nutrient table. FeedXL will warn you if the calcium to phosphorus ratio is too high or low!
Copper, Zinc, Selenium and Iodine
I am grouping all of these trace minerals together because they all share the same characteristic that they are almost ALWAYS at low levels in forages. Which means they are nearly always deficient in diets before you add fortified feeds or supplements.
This means that you can aim to keep these nutrients as close to 100% as possible. The diet shown here uses a single vitamin/mineral supplement to meet trace mineral requirements.
This is what the diet looked like before I added the supplement:
You can see these 4 minerals are all low. I used the Supplement Finder (i.e. The BIG PINK BUTTON) to find a supplement that would fill all of these gaps. Ideally what you want to see when you use a single supplement is that at least one of these minerals is sitting very close to 100%. That is your green flag that you have the amount of supplement at the right level. Increasing the amount from this point is just a waste as all requirements are already met, while reducing it would mean the amount of this nutrient (selenium in this example, which is sitting at 101%) would no longer be meeting requirements.
The same rules also apply when using a fortified feed to meet vitamin and mineral requirements. Except that you also have to consider the amount of Digestible Energy the feed is adding.
This is not a super simple concept, so if you are confused, please keep asking questions, as the more you understand this, the easier it will be to use FeedXL effectively.
Quick tip: You can try to keep copper, zinc, selenium and iodine as close to 100% of requirements as possible. If these nutrients are above 200% I would be trying to find ways to reduce them. This may mean switching feeds or supplements!
Manganese, Iron, Magnesium and Potassium
These minerals are almost always HIGH in forages. Therefore you will almost always see them sitting well above your horse’s 100% level in the diet. Is this a concern? No. There are always exceptions, but for the majority of horses, no, it is not a problem when these minerals are well above 200%.
Thing is, because these nutrients are rich in forages, it is almost impossible to get them closer to the 100% mark. You could reduce the amount of forage, but the downside of that (higher risk of ulcers, boredom, compromised hindgut health, higher risk of dehydration and colic) far outweighs any potential upside. In fact unless levels in the forage are extreme and the bar for a nutrient goes red, there really is no upside to reducing forage.
If you are concerned, because sometimes it does look scary, just read the notes in the Nutrient Table or the hover box on the graph to put your mind at ease. For example, Iron in this diet is at 331%. Which seems really high! But, the notes will tell you:
“While Poet’s iron is higher than it needs to be it is still within the safe range. Poet’s upper safe level for iron is 6,019 mg or 943% of his RDI”
So the upper safe limit is 943%. This diet is a long way off that, so even though 331% seems high, it is very much within the safe zone!
For those of you who like to look at the iron: copper: zinc: manganese ratio, it is calculated for you in the Nutrient Table.
Sodium and Chloride
Sodium and chloride are the two components of ordinary table salt. So together they can make a feed taste very salty. If a feed gets too salty your horse may stop eating it, because it simply doesn’t taste good (and can’t blame them!). So I like to keep sodium as close to 100% as I can, by adjusting the amount of salt in the diet.
There are a few exceptions. If your horse is in a very hot and humid climate you may need to feed more (more info here https://feedxl.com/40-electrolytes/) or if you are trying to increase water intake for some reason, more salt is useful. But under normal conditions, sitting sodium at or very close to 100% is best. BUT also always make sure your horse has access to free choice salt!
Chloride is a bit of a lucky dip and its final level in a diet will depend on the amount in your forages. I don’t pay too much attention to where chloride ends up. In fact I don’t think I have ever had to adjust a diet specifically to change the level of chloride (for any dairy nutritionists reading this, it does play a big role in DCAD, but that is another story for another day 🙂 ).
Vitamin A
If you are obsessive about getting nutrients close to 100%, Vitamin A is your friend! You will notice it is nearly always sitting on 100% of requirements. Why?
Well, in forage, the ‘vitamin A’ content is not active vitamin A. It is in the form of Beta Carotene which can be converted to vitamin A IF your horse needs vitamin A. So they will only convert it if they need it.
FeedXL models this physiology and takes into account ALL vitamin A from feeds and supplements as this will be an active form of vitamin A (which can become toxic so we need to count all of it). But then FeedXL will only convert vitamin A to active form from forages IF your horse needs more vitamin A.
For example, if your feed + supplement provides 80% of your horse’s requirement for vitamin A, FeedXL will just top up the remaining 20% of vitamin A from forages to meet 100% of your horse’s requirement. Which is why Vitamin A is very often sitting right on 100%.
If your feeds and supplements provide more than 100% of your horse’s requirement for vitamin A you will see it above 100%. This is OK, as long as it is within safe limits (though personally I would keep it under 200%).
Vitamin E, Vitamin B1 and Folic Acid
I am grouping these three together because they will often be low in diets before you add some kind of fortified feed or supplement. And they are all relatively expensive nutrients, so for the sake of cost, you want to make sure your horse’s requirement is met, but if levels of these vitamins go above 200%, you may be paying a lot for nutrients your horse doesn’t really need. I like to keep them between 100% and 200% if I can. In the case of this diet, the supplement I used was rich in Folic Acid so it has tipped above 200%, but the E and B1 are at nice levels so I am not going to worry about the Folic Acid in this case.
Quick Tip: Keeping these nutrients below 200% will make sure the diet is not excessively expensive!
Vitamin B2, Niacin, Vitamin B5 and Vitamin B6
This crew are all grouped together because forage is OFTEN high in these vitamins so you will normally see levels WELL ABOVE 100% for all of these vitamins. Is that something you should be concerned about? Not at all. In fact all of these except vitamin B6 are considered non-toxic. And the vitamin B6 upper safe level is very high (in this diet the upper safe limit is 5000%!!).
Quick Tip: I essentially ignore these nutrients as long as they are ‘green’. They will almost always be well above 100%, but it is nothing to be concerned about!
I hope that helps you a little to read the graph and to put your mind at ease about what is and is not normal for certain nutrients. If you have questions, please be sure to ask in the FeedXL Horse Nutrition Forum on Facebook!! We truly want you to know as much as you can about what FeedXL is showing you!
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
Magnesium oxide. It’s one of those ingredients people love to disagree over, should we use it, shouldn’t we use it, is it bioavailable or not for horses??
Part of this contention is due to the fact that magnesium oxide is a created ingredient… it is cooked in a process called calcination, that reacts magnesite with oxygen to create magnesium oxide.
Like all things, it can be made well, or it can be made poorly, and this then impacts on whether it will be bioavailable or not. So it’s not like limestone (calcium carbonate) that is mined for example and is generally always the same.
So when reading about magnesium oxide for horses, keep in mind that most studies do not report the conditions under which it was manufactured OR its final particle size, both of which have a huge impact on final bioavailability.
I still believe that quality magnesium oxide is a very useful source of magnesium for horses, but then I am very fussy when it comes to where it comes from and how it is produced!
And for anyone who loves details, this is a now old but still informative paper on this subject (Beede et al 1992). It is a Dairy paper but talks in detail about factors affecting magnesium oxide bioavailability: https://animal.ifas.ufl.edu/apps/dairymedia/dpc/1992/Beede.pdf
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
The last two weeks has seen extreme weather conditions for us in my local area in Australia. In the last 14 days, 7 days have been 40 degrees celsius or higher (104 F +) and of the other 7 days only one was below 37 degrees C (99 F). To make things worse, the nights will not cool down, with most nights remaining over 20 degrees C (68 F) and a couple of nights being 26 + degrees C (79 F). On more than one occasion I have checked temperatures between midnight and 3 am and it has been 30 degrees or more in the middle of the night! It is HOT!!!
My horses are crusted in salt from continuous sweating. I took pity on them today and instead of having them out grazing with muzzles on they have hay in their hay pillows so they can at least stay in the shade.
But back to salt. I normally just let my horses eat salt free choice. Their balancer pellet gives them about 5 grams of salt per day and the rest of what they need they eat as loose rock salt.
BUT, the last couple of weeks I have been adding it to their feeds so I know they are getting enough to keep sweating. If horses run low on sodium or chloride they can’t sweat, and that, in these conditions is life-threateningly dangerous.
There is a trend at the moment though for people to add large amounts of salt to their horse’s daily feeds, despite actual requirements or what may be coming from the rest of their diet. Blanket recommendations like ‘add 10 grams of salt per 100 kg of bodyweight’ seem to be commonplace, yet don’t seem to take into account a horse’s specific situation.
Take Poet’s diet for example, shown in the graph below. If I add 10 g/100 kg of BW to his diet his sodium intake is well over 200% of what he needs. In these extreme conditions this may well be accurate, but once it cools off a little this is way more sodium than he needs.
While I was out just now giving them hay I had the thought ‘I wonder what this excessive salt might be doing to the bacteria in their gut’?? Salt is, after all one of the best known and most widely used anti-bacterial agents in the world.
So I did a little research… and while not much came up, there is a recent paper, published in ‘Nature’ (i.e. one of the most reputable journals in the world, so we can trust it) showing that in both mice and men adding more salt than normal to a diet affected the gut bacterial populations, in some cases it entirely wiped out certain strains of bacteria! Eek!
What is really interesting (from a human perspective) is that the researchers were then able to link those shifts in gut bacteria to high blood pressure, which may help to explain (the as yet poorly understood) link between high salt diets and hypertension.
Back to your horses though… feeding excessive salt is unlikely to have any benefit and may be negatively affecting the good bacteria in your horse’s gut. So when using FeedXL, just meet your horse’s requirement for sodium with salt that is added to the diet. Then leave free choice salt (preferably as easy to eat loose rock salt) out so they can top up any extra requirement they may have.
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
