What are the Symptoms of Mineral Deficiency in Horses?

“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!

New to FeedXL? Click here to learn more about our horse nutrition calculator.

Magnesium Oxide for Horses

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!

We have information on various sources of magnesium for anyone who would like to read some more here: https://feedxl.com/36-which-form-of-magnesium-is-best/

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

 

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Iron: Is There a Link to Laminitis?

Dietary iron is thought by some to contribute to the incidence of laminitis in horses, with serum ferritin starting to be used as the measure of iron status.

I (Nerida) don’t know if this is the case, but in reading human literature, it seems the relationship between serum ferritin and inflammation is a bit of a case of chicken or the egg. Lots of information shows serum ferritin is elevated in humans with inflammatory disease and/or metabolic syndrome, but it is not clear what happened first; did serum ferritin rise and cause inflammation, or did inflammation and cell damage occur and cause elevated serum ferritin?

So I thought a good place to start is with a link for you to a review on serum ferritin. This article tells us that serum ferritin is actually a little protein ball, with a hollow centre (my words) where it keeps iron. Depending on how much iron is available in the body, the amount of iron inside the ferritin can vary a lot.

When serum ferritin is measured, it is the protein that is being measured, not the iron. So a serum ferritin measure tells you how many little protein balls are there but not how much iron they actually contain.

The other interesting thing to note is that ferritin is made within cells and is not made in the blood. So it seems that for ferritin to get into the blood it has to come out of the body’s cells (with very limited evidence if any, according to these authors, of any regulated ferritin secretion mechanism in mammals). This leads to the hypothesis that the elevated serum ferritin seen during inflammation is due to leakage from damaged cells into the blood.

The paper goes on to talk about the relationship between serum ferritin and liver iron stores, which are considered the gold standard for assessing body iron stores. While serum ferritin is usually related to liver iron in ‘normal humans’ that don’t have inflammatory disease, serum ferritin can both under and over-estimate liver iron stores where some form of inflammatory disease is at play.

Meaning it is not necessarily a good indicator of overall iron status. These authors suggest serum (‘soluble’) transferrin receptor (sTfR) as being much more useful.

Anyway, there is a lot to take in and I have only had one read over and would need to read it many times to fully appreciate all of the content. The simple point I want you to take away is that serum ferritin is not necessarily an indicator of iron overload from high dietary iron and may instead be an indicator of inflammation. Maybe the chicken came first… or was it the egg??

I’ll keep reviewing papers over the next several months! 

Here’s a direct link to the article mentioned above: https://pubs.rsc.org/en/Content/ArticleLanding/2014/MT/C3MT00347G

 

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Iron for Horses: Could Forage Be Enough?

Comparison of equine dietary iron requirements to iron concentrations of 5,837 hay samples

N. Richards and B.D. Nielsen, 2018

Introduction

Iron is essential for the production of red blood cells. According to the 2007 Horse NRC, Fe requirements are 50 ppm for growing foals, lactating and pregnant mares, and 40 ppm for all other classes of horses. The 2005 NRC suggested a maximum tolerable Fe concentration of 500 ppm using data from other species. It is claimed that excess dietary Fe is causative of horses becoming insulin resistant.

Athletic horses, and particularly those in Thoroughbred racing, are often supplemented with Fe in an attempt to improve performance. Supplementation is commonly carried out without any formal analysis of the diet to determine if additional iron is required. Forages are typically high in iron and supply a majority of iron in all equine diets.

This study looks at the iron concentration in forages typically fed to equines and whether iron from forage is enough to meet the iron requirement of an athletic horse.

Methods

Nutrient concentrations from hay samples submitted for analysis in 2017 and for which Fe was measured were obtained from Equi-Analytical, representing 3,060 grass, 1,193 legume, and 1,584 mixed hay samples.

Iron concentration was measured using inductively-coupled plasma mass spectrometry (ICP). Analysis methodology is available from dairyone.com Statistical analysis was performed using Proc MEANS of SAS.

Results

Iron was highest in Legume and Mixed Mainly Legume Hays and lowest in Grass Hay (Table 1). All hay types had a mean iron concentration more than five times that required by athletic horses and a median iron concentration more than three times.

From all hay samples (n = 5,837), 707 contained Fe at or above the suggested tolerable threshold of 500 ppm, while only 81 contained Fe at less than 50 ppm. Further, only 15 contained Fe at less than 40 ppm.

Discussion

A 500 kg horse in heavy work has an iron requirement of 500 mg/day (NRC 2007; based on a daily feed intake of 2.5% bodyweight and a requirement of 40 ppm). Forage intake is often restricted by Thoroughbred trainers. But even when fed at 1% of bodyweight to a 500 kg horse, these hays will supply an average 1,060 mg to 2,230 mg of iron per day, supplying more than 200% of daily iron requirements in the forage component of the diet alone.

Fortified grain concentrates are fed at an average 2.5 kg/horse per day in Australian Thoroughbred racing stables (Richards 2003). These concentrates have an average iron concentration of 190 ppm (FeedXL.com), adding an additional 475 mg/day of iron to the diet of these horses. Almost 60% of Australian Thoroughbred trainers then add an iron supplement to their horses’ diets (Richards 2003). It is expected similar trends would be found in the USA.

Based on this broad diet analysis, forage is able to meet the daily iron requirement of athletic horses. When iron from fortified feeds and supplements is added, there would be few racehorses receiving less than 300% of their daily iron requirement. It’s not unexpected that many horses would be receiving in excess of 500% of their daily iron requirement

What About Insulin Resistance

Given the dearth of Thoroughbred racehorses that are insulin resistant, despite Fe supplementation in combination with diets that can easily supply amounts beyond requirements, it seems unlikely excess Fe causes insulin resistance. However, it is recognized insulin resistant horses may have elevated serum ferritin.

References

Council NR. Nutrient Requirements of Horses: Sixth Revised Edition. Washington, DC: The National Academies Press, 2007.

Richards N, Hinch G, Rowe J. The effect of current grain feeding practices on hindgut starch fermentation and acidosis in the Australian racing Thoroughbred. Aust Vet J 2006;84:402-407.

FeedXL Nutrition Software, https://feedxl.com/, 2018.

HUGE THANKS to Equi-Analytical for providing the data to write this paper, which was presented as a poster at the recent International Conference on Equine Exercise Physiology (ICEEP).

 

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What You Should Know About Phosphorus and Phytate

Horses are unique because they absorb phosphorus from their hindgut… which is a stroke of genius on a horse’s part… here is why.

Phosphorus in grains, legumes/oilseeds is bound up in a compound called phytate. ‘Phytate bound phosphorus’ is as good as indigestible for most monogastrics who absorb phosphorus from their small intestine (like pigs and poultry).

But horses enlist the help of their oh so useful hindgut bacteria to break down the phytate for them and release the phosphorus for absorption! Clever!!

So if you ever read statements about specific ingredients like soybean meal containing indigestible phosphorus because they contain phytate, think two things:

1. ALL grains and legumes/oilseeds contain phytate; and
2. Horses have got a useful arrangement with bacteria and a different site of absorption (their hindgut) that allows them to access the phosphorus.

It’s a very well designed aspect of the horse’s gastrointestinal tract!!

 

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Vitamin C for Horses?

Did you know Vitamin C is not an essential nutrient in your horse’s diet? Unlike we humans, who will get scurvy and die if we don’t eat vitamin C, horses make their own vitamin C in their liver! Clever right!!

There are some situations, like when a horse is very ill, really stressed or has liver damage where supplementing with vitamin C may be useful. Just be mindful that when you want to stop supplementing you should remove the vitamin C from the diet gradually so the horse has a chance to ramp its own production up again.

 

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Diet Lacking in Vitamin E?

We are frequently asked about how to add Vitamin E to a horse’s diet when all other nutrient requirements are being met. Vitamin E is abundant in fresh green forages and many horses will meet their daily requirement of Vitamin E with adequate intake of good quality pasture. Vitamin E declines over time in stored feeds including preserved forages. Most commercial pre-mix feeds and vitamin & mineral supplements account for this and are formulated with supplementary Vitamin E.

At times when pasture is average or poor quality, overgrazed or simply not available, diets which previously had adequate Vitamin E may become low as a result. Sometimes even with a good quality pre-mix feed or vitamin & mineral supplement, the Vitamin E levels may still not be adequate within the diet.

Additional vitamin E can be safely added to diets and can be found in FeedXL’s blue ‘Balancers & Supplements’ tab under ‘Antioxidants’. Antioxidant supplements commonly contain both selenium and vitamin E. Unless the diet requires additional selenium, look for supplements which contribute only vitamin E to your horse’s diet.

To find vitamin E only supplements, click on ‘Complete Data’ which is located below the ingredient name when editing diets or browsing ingredients and FeedXL will show you which nutrients that product contains. (See the image in this post).

Another consideration when choosing a suitable Vitamin E supplement is the form of Vitamin E to supplement with. Natural vitamin E is reported to be more effective in raising plasma  Vitamin E concentrations when compared with a synthetic source. To know which is which you will need to read the manufacturer supplied information for each product on their website or product labels.

 

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Vitamin B6 for Horses

This little vitamin is not talked about much in equine nutrition, mainly because we still don’t know exactly what a horse’s dietary requirement is. We also assume a large part of their requirement is fulfilled by the Vitamin B6 produced by the bacteria in their hindgut.

We do know B6 is important for building muscle. I just saw a very recently published paper looking at Vitamin B6 supplementation and muscle development in rabbits. (https://www.publish.csiro.au/AN/AN15807…)

I know a rabbit is very different animal to a horse, but from a gut physiology and nutrition perspective they are actually really similar, so I thought I would take a look to see what the researchers found.

Vitamin B6 supplementation was shown to significantly alter protein metabolism and increase the ratio of fore + hindleg muscle weight to body weight (i.e. supplemented rabbits had more leg muscle). Interesting!

We do track B6 intake in our Pro FeedXL plans … this just reinforces to me though how important a horse’s base diet is when it comes to achieving specific outcomes. For example, if you are wanting your horse to build muscle but you aren’t meeting basic nutrient requirements (like vitamin B6) you could add all the fancy muscle building supplements you like to the diet and they won’t help!

You can’t build muscle unless you get your basics right first! Here at FeedXL, we can help you with that! Take a look at our plans and pricing here.

 

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What Is an Organic Mineral?

We all hear the term ‘organic mineral’ being used in horse nutrition. But what does it actually mean?

Its definition is pretty basic… an organic mineral is simply a mineral that is attached to something that contains carbon.

For anyone who can stretch their mind back far enough to the sometimes dreaded chemistry classroom, you might remember a subject called ‘Organic Chemistry’ which dealt with the chemical goings on of ‘carbon-containing compounds’. So a mineral attached to a carbon-containing compound is called an ‘organic mineral’.

For example, copper sulfate is an inorganic mineral, as it is simply one copper attached to one sulfur and four oxygen atoms (i.e. no carbon). Copper proteinate on the other hand is copper attached to a tiny piece of protein. Protein contains carbon atoms, so a copper proteinate is classified as an organic mineral.

It is easy to be confused by the word ‘organic’ these days as it is most commonly used to describe food produced without the use of synthetic herbicides, fertilisers or feed additives. You need to be careful not to transfer the mostly positive associations of organic food onto the use of organic minerals in horse nutrition.

The benefits of organic minerals for horses, perhaps with the exception of organic selenium, are largely undocumented… yet, unfortunately, widely claimed. I will write more on this another day! 

 

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Oil for Horses: Good or Bad?

Hard working horses have enormous requirements for energy that are traditionally filled using high grain rations fed together with chaff and hay. However, feeding large amounts of grain does come with its own set of issues which can include colic, hindgut acidosis, nervous or fiery behaviour, tying up and loss of appetite. Oil has gained popularity in recent years as a substitute source of energy for working horses, but is it effective, how much can be fed, are all oils equal in the benefits they can provide and do they cause any health issues of their own?

A little bit goes a long way

The biggest benefit oils provide working horses is their very high energy content relative to grains. Oils contain nearly 3 times more energy than oats, with 400 mls of vegetable oil providing as much energy as 1 kg of oats. The real benefit in this is you can reduce the size and sheer bulk of feed a horse has to consume without reducing calorie intake, allowing you to get enough ‘feed’ into horses with poor appetites. The end result being these horses can hold their weight and continue to train and compete for longer than they otherwise would on a more traditional diet.

Reducing heat load

Oils generate less heat during the digestive and metabolic processes than an equivalent amount of grain or forage. Feeding oil also means that you can feed less grain and still meet energy requirements. Combined, this means that high oil diets place less of a heat load on working horses, reducing electrolyte losses and the amount they need to sweat to stay cool, a big bonus for hard working horses, especially those training and racing in hot environments or working over very long distances.

Saving glycogen

Fatty acids from oils are the preferred fuel for muscles during slow and medium pace work while glycogen is the only source of energy a muscle can use during sprints and strenuous exercise. Once a horse runs out of glycogen its muscles fatigue and the horse will slow down and lose the ability to perform at the level it is capable of. Feeding oil in diets provides a source of fatty acids for muscles to burn during the warm up and slower phases of a competition, meaning muscles are able to conserve valuable glycogen and avoid fatigue.

Problem solving

‘Problem horses’ and particularly those that tie up or get excited and nervous on high grain diets will often benefit from rations that provide a portion of the dietary energy from oils. It is thought that the positive effects seen in these horses on high oil diets is due more to the reduction in grain intake as opposed to the addition of oil, but using oil in the diet allows you to reduce grain intake without compromising energy intake and performance.

Oils aint oils

All oils contain virtually the same amount of digestible energy, but there are other differences you may want to consider when looking to purchase an oil, including:

Essential Fatty Acid Content: Horses need omega 3 and omega 6 fatty acids in their diet. Grains are naturally high in Omega 6, so for horses on a high grain diet, it is preferable to choose an oil with some omega 3 content. The table below shows the amount of omega 3 and omega 6 in some commonly used oils. Linseed and canola oil contains the highest omega 3 fatty acid content of the natural vegetable oils.

Ingredient Name Omega 3 (%) Omega 6 (%)
Linseed (Flax) Oil 57 13.9
Cod Liver Oil 25 2
Canola Oil 10 20
Soybean Oil 7 52
 Corn Oil  1  55
 Olive Oil  1  11
 Rice Bran Oil  1  39
 Sunflower Oil  0.3  60
 Coconut Oil  0.1  2


Palatability:
Some linseed oils and fish oil including cod liver oil are notoriously unpalatable for horses, so while these oils are useful for providing omega 3 fatty acids, they can’t be fed in large amounts as most horses simply won’t eat them.

Processing Method: Oil is extracted from oilseeds in two main ways; cold pressing where oil is squeezed out of seeds, often in a water cooled environment to keep the oil at less than 60C; and solvent extraction where a solvent like hexane is added to extract oil from seeds. The oil is then heated to remove the hexane. Cold pressed oils tend to be higher in quality as more of their essential fatty acids and natural antioxidants are left intact in comparison to solvent extracted oils.

It takes time

Horses need time to adapt to digesting and metabolising oils. Oils should always be introduced into a diet slowly, starting with ¼ cup of oil per day and increasing this by ¼ cup every 5 days until you reach the full amount you want to feed. Introducing oil into a diet too quickly can result in soft manure and reduced fibre fermentation in the hindgut.
It will take a minimum of 3 weeks before a horse starts to really benefit from the oil in its diet and it could take up to 3 months before the full benefits of oil are realised.

How much can you feed?

Horses can be fed up to 20% of their total energy intake as oil, which in real terms means just over 3 cups of oil per day for a 500 kg horse in full work. While this level of oil is useful for horses that tie up, very few horses are fed this much oil per day. Feeding between 1 and 2 cups of oil per day is enough to give horses the benefits discussed above without making diets messy, unpalatable or unnecessarily expensive.

Good Stuff

Oils are ‘good stuff’ for working horses. They reduce reliance on grains, make the amount of feed a horse needs to eat smaller, keep horses cooler, allow horses to conserve muscle fuel for sprinting, give horses that tie up a safer and more effective source of energy and provide essential fatty acids in the diet.

For the best results, introduce oils slowly into the diet and select oils based on the following: their omega fatty acid content with oils containing some omega 3 fatty acids preferred; palatability, be aware that some oils including linseed and fish oils can be unpalatable; and method of processing, with cold pressed oils preferred over solvent extracted oils.

 

Meet The Author: Dr Nerida Richards


Dr Nerida Richards is FeedXL’s resident equine nutrition specialist. With 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 Nerida is able to help FeedXL members solve any problem they may come up against with feeding their horses. To learn more about Nerida and to ‘meet’ the rest of the FeedXL team, check out our About Us page here.

 

Do you have a question or comment? Do you need help with feeding?

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