Tag Archive for: digestion

The One Tiny Change to How You Feed Your Horse That Could Make a BIG Difference

Have you ever thought about whether the order you feed various things to your horse will make a difference to his health?

Chances are you haven’t.

I know before I was a nutritionist the thought would not have occurred to me!

But new research is showing that feeding a small amount of hay before you feed your concentrates/grain reduces the post-feeding inflammatory effect of non-structural carbohydrates (starch and sugars).

In other words:

Feed hay first (about 1 kg, 2.2 lb). And then feed your grains/concentrates.

Researchers from Ohio State University and Virginia Tech have recently published research showing that feeding non-structural carbohydrate (NSC) in amounts of 1.14 g/kg of your horses bodyweight (which roughly equates to 1 kg (2.2 lb) of a 50% NSC feed, 2 kg (4.4 lb) of a 25% NSC feed) causes post-feeding inflammation.

Suggesting that sub-clinical ‘digestive stress’ occurs at much lower levels of intake than that required to cause noticeable physiological changes.

The ‘post-prandial inflammation’ measured was an increase in plasma concentration of interleukin-1b. Interleukin-1β (IL-1β) is a potent pro-inflammatory cytokine. When present in excess, IL-1β will contribute to unhealthy levels of inflammation.

These same researchers have now shown that when you feed 0.91 kg of grass hay (approximately half of a flake/biscuit) before feeding any higher NSC concentrate feeds, the recorded levels of post feeding IL-1β were lower than if horses were fed their concentrate first and then hay!

Feeding hay first also reduces post feeding blood glucose levels

What I find really interesting is that in humans, exposing human intestinal tissue to IL-1β reduces ‘tight junction’ integrity and may be contributing to leaky gut syndrome! Yikes!! This is all getting pretty technical… suffice to say that inflammation in the gut won’t end well (for us, or our horses!).

What should you do?

Well, either make sure your horse is able to graze or eat hay right up to when you feed your concentrates. OR if your horse is meal fed, feed 1 kg (2.2 lb) of hay BEFORE you feed your concentrates.

Combining this practice with also feed alfalfa (lucerne) before you ride is going to improve your horse’s gut health immensely! And it’s so simple. Hay before you ride, hay before you feed!

Thanks for reading this far!

These small changes can make such a huge difference to your horse’s health and wellbeing! And that is truly what gets me, and everyone on the nutrition team here at FeedXL to work every day with a smile on our faces!

As always, if you have any questions about anything to do with feeding and nutrition, head on over to our FeedXL Horse Nutrition Group on Facebook, you are so welcome, FeedXL member or not!



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

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Confessions of a Horse Nutritionist #3: Colic

OK, this is a good one… Poet was getting colic regularly last spring.

And I was the cause… yikes!

You’d think I would learn, but nope, took me a little while to figure this one out!

What was going on? Here is the story…

I came home from somewhere one day last spring and noticed Poet wasn’t himself… he was laying down, half rolling, standing up… you know that thing horses do that sends us COLD as horse owners. He had colic!

I called my vet, he was out of town, but as I walked Poet around in the roundyard we discussed symptoms. As we chatted Poet ate some grass and did a poo, but was still uncomfortable.

I had to leave to go and pick the kids up from school. When I got back, he seemed normal. I watched him like a hawk but he was back to normal Poet. Excellent I thought, dodged that bullet.

Fast forward (and I forget now the exact time frames, but let’s say… a week) and, colic, again! Same thing, uncomfortable laying down half rolling repeatedly. So I called Doug, he came to check him out! Seriously noisy guts! Gas colic, or as I have heard some vets call it, the dreaded trapped fart!

The colic resolved again on its own… but this time, with the revelation it was likely gassy colic, I started to figure out the problem!

Our pasture in spring was almost all ryegrass and self-sown wild oats, both grasses that can accumulate high levels of fructan. And fructan ferments fast in the hindgut creating gas that was getting trapped in Poet’s gut.

OK, I thought, I can manage that!

BUT… there were days that for whatever reason I would give the horses a ‘little bit more’ pasture on their grazing strip than normal. For the most part I didn’t really think much of it, it would be a bit colder or I’d feel like they needed more (it’s that whole guilt thing kicking in!) and so they would get a bit more pasture which meant more of these high fructan grasses.

And twice on the days I gave them more he colicked again! DUH! Finally got it!! Too much high fructan pasture was causing excessive gas production and Poet just couldn’t get rid of the gas!

From then on I was very strict with the amount of pasture they got (which yes! I should have been in the first place… lesson learnt!) and we didn’t get any more colic and haven’t had any episodes (touch-wood) since!

It was a good lesson in how seasonal conditions can affect horse health. And in how diets need to be adjusted accordingly to manage these seasonal issues.

This spring I am being very mindful of how much spring grass he gets. My new place doesn’t have the same type of pastures. There is still ryegrass, but virtually no oats, so the risk is potentially lower.

Still… I am not taking that chance so they are getting less access to the pasture to manage the risk of colic (and laminitis!).

Because I still need to keep forage intake up, I use low sugar hay (in my case Rhodesgrass) to safely fill in the forage gap in their diet along with their usual lucerne/alfalfa each day. And all is well so far.



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!

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What Can You Do to Reduce the Risk of Colic?


It’s a word that sends cold shivers up every horse owners’ spine, and for good reason!

Colic is the single biggest killer of horses worldwide.

I lost my beautiful CoaCoa to this horrid condition… with their gastrointestinal tract the way it is, horses are simply prone to developing all sorts of problems with their gut.


There are certain conditions that will increase the risk of colic. So there are things we can do to reduce the risk of colic.

Research presented at the European Equine Health & Nutrition Congress, March 2017 (by Lindroth et al) found the following:

  1. Change of water source and/or a change of roughage more than twice (though the time period is not specific) doubled the risk of colic.
  2. Horses fed concentrates three times per day had twice the risk of colic compared to horses not fed any concentrates (amounts were not specified though)
  3. Here is the REALLY USEFUL bit: For every 1 kg increase in roughage (forage) per 100 kg bodyweight fed per day, the risk of colic DROPPED by three times!
  4. For every 1 kg increase in muesli feed (composition not specified but would think it contains grains) per 100 kg of bodyweight, the risk of colic INCREASED by three times.Which makes a whole lot of sense, given the more forage we feed and the less concentrate, the closer we are to a horse’s natural diet.

And when we can keep them closer to their natural diet, their gut and overall health is almost always much better!

So more hay, less grain, less risk of colic!



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!

Click here to join the FeedXL Horse Nutrition Facebook Group


horse standing at fence

Psyllium Husks

Is your horse in drought conditions? Mine too!

It has been drought here for more than 2 years now… and something I am really, really bad at remembering to do is feeding psyllium husk regularly to clean accumulated dirt and sand out of their gut.

So here is a reminder, feed psyllium husk!

If your horse is in drought conditions or kept in a dry-lot or on very sandy ground, the psyllium will help to shift all the accumulated dirt and sand out of their gut.

If you don’t get it out, it will cause irritation and pain and you may see signs of bloating, diarrhea or colic.

Feed 50 grams per 100 kg of bodyweight (or 2 oz per 250 lb) for 4 days in every month. Add it to a feed your horse really likes, and just damp it down ever so slightly to make the psyllium stick to the feed.

Don’t wet it! It will into a gooey mess your horse probably won’t want to eat (and I can’t blame them).

Consider yourself reminded 😂! My cheeky lot are up to day 3 for this month.



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!

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Manure Score Chart: How to Quickly Check Your Horse’s Hindgut Health

While it’s maybe not the most refined subject, your horse’s manure can tell you a lot. How watery, soft, formed, unformed or hard it is can give you some insight into what is going on inside that gut!

Use our quick check guide to assess your horse’s manure and see if it is telling you all is well… Or if there is something not right within the gut. Note that the color of the manure will change as what the horse is eating changes. So don’t be too distracted by colour, look instead at the form.

Score 1 – watery diarrhea

Watery Diarrhea

Is this normal?

Something is seriously wrong in your horse’s gut. You need to contact your veterinarian immediately!

What causes this?

There are many causes of watery diarrhea. Please work with your veterinarian to achieve a sound diagnosis

How to fix it:

Follow directions from your veterinarian.

Score 2 – diarrhea

Is this normal?

Not normal! Like watery diarrhea, there are many causes of diarrhea in horses. Please work with your veterinarian to isolate the cause.

What causes this?

You should work with your veterinarian to diagnose the cause of your horse’s diarrhea.

How to fix it:

Follow directions from your veterinarian.

Sand and dirt accumulation in the gut is a common cause of diarrhea in horses. If this is the diagnosis, you can follow our protocol for using psyllium to clear this from the gut. Click here to learn more about our psyllium husk protocol.

Score 3 – soft, unformed

Is this normal?

This is a not a normal consistency for horse manure and indicates that something is not right in the gut, particularly the hindgut. The ratio of water to fibre is too high in the manure.

What causes this?

There are many possible causes, including:

  • hindgut acidosis. If your horse is being fed unprocessed grains like wheat, corn (maize) or barley, large amounts of starch will be fermented in the hindgut. Or your horse may have large amounts of fructan entering the hindgut from ryegrass or cereal (oat, wheat barley) forages. The fermenting starch and/or fructan upsets microbial balance and large amounts of acid accumulate. The acid damages the gut wall, good, fibre fermenting bacteria die and overall health is compromised. Soft manure is a common symptom. You may or may not see whole grains still present in the manure.
  • sand or dirt accumulation. Sand/dirt irritates the gut wall. A common symptom is soft manure.
  • too little fibre. When there is not enough effective (indigestible) fibre in the diet, there is not enough fibre to hold onto water in the hindgut, leading to soft manure.
  • high moisture, low fibre pasture. Lush, young pasture is high in water and low in fibre. Horses will often have soft manure on these pastures due to the high water and low fibre intake. Horses may also eat bark, chew on fence posts or other objects to try and increase fibre intake.

How to fix it:

The solution here depends on the cause.

  • hindgut acidosis, if grains must be fed, use only cooked grains. Feed grains in small meals (no more than 1 kg/meal for a 500 kg horse; 2lb/meal for an 1100 lb horse). Only use grains when absolutely necessary!
  • sand or dirt, use psyllium husk to remove from the hindgut. Follow our protocol here.
  • too little fibre, reassess your horse’s diet and make sure you are feeding a minimum of 1.5% of BW per day in quality forage, preferably as long stem hay, haylage or pasture. For optimum gut health, aim for 2% BW in forage per day.
  • high moisture, low fibre pasture. If your horse is grazing lush pasture, provide free choice access to a high fibre hay to allow your horse to choose how much fibre to consume.

Score 4 – soft, formed

Is this normal?

This is a normal consistency for manure and indicates your horse is well hydrated and consuming sufficient fibre in the diet. This soft, formed consistency is normally seen when some green pasture is available daily.

Score 5 – firm, formed

Is this normal?

This is a normal consistency for manure and indicates your horse is well hydrated and consuming sufficient fibre in the diet. This firm, formed consistency is common when horses have access to hay or dry pasture.

Score 6 – hard, dry

Is this normal?

This is a not a normal consistency for horse manure and indicates that this horses water intake is low and dehydration may be present. Or it indicates that indigestible fibre intake is too high.

What causes this?

Reduced water intake may be due to:

  • water that is too cold
  • dirty, unpalatable water
  • unfamiliar water (common when traveling)
  • electrolyte (particularly sodium) deficiency. When sodium levels drop in the blood horses reduce water intake.
  • water placed in an area the horse does not feel safe drinking (e.g. at the back of a pasture or stall)
  • stress/anxiety, common when competing or travelling
  • excessive indigestible fibre intake may be seen when horses have access to straw or other similar mature forage like old, dry pasture as their major forage source.

How to fix it:

Increase water intake and reduce indigestible fibre intake.

Ways to do this are:

  • use water warmers
  • keep water so clean that you would drink it yourself
  • take familiar water or a familiar flavour with you when traveling
  • add more salt to your horses feed (use FeedXL to work out a sensible amount)
  • place water in a place your horse feels safe
  • keep your horse with a buddy who drinks well to reduce stress/anxiety
  • feed limited amounts of straw or similar forage (limiting to 1% of bodyweight where hard manure is an issue). Use more digestible forage to provide the remainder of your horses required forage intake.



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!

Click here to join the FeedXL Horse Nutrition Facebook Group


Dark brown horse looking bavk

Horse Digestive System: Equine Gut Health

The gut health of our equines plays a significant role in determining how healthy or unhealthy our horses will be. The equine digestive tract is a large and relatively complex system. Your horse’s health depends on how well you look after this digestive system and importantly, how well the microbial population within it remains “balanced”.

We are really only just beginning to understand how important your horse’s digestive health is to his overall health and wellbeing. But we know that it is so important! So if there is one area of equine nutrition you should devote your time to in order to improve your horse’s overall health, it is this one!

The following article gives you an introduction to equine gut health. It looks at the structure and function of the gut and the digestive process, how the way we feed horses impacts on the equine digestive system and it’s microbial population, and briefly covers some of the diseases and disorders that can occur when we feed in a way that doesn’t support digestive health.

Understanding How Horses Digest Food

Your horse’s digestive system is comprised primarily of the stomach and small intestine, cecum and colon. For a detailed description of the horse’s gastrointestinal tract, please see https://feedxl.com/31-the-gastrointestinal-tract/

Horse GI Tract

The digestive tract’s most important function is breaking down food. The equine digestive process occurs in every section of the horse’s gut. The digestive process is simply “big things being broken into small things”. Once nutrients are broken down into small enough parts, they can be absorbed into the bloodstream.

The digestion and absorption occurs the entire length of the animal’s digestive system. But the way it happens in each section is different.

The Stomach

The stomach’s primary role is to hold food and then pass it slowly to the small intestine where it will be at least partially digested. The start of the digestive process does, however, occur in the stomach.

In the stomach, the horse uses hydrochloric acid and digestive enzymes to begin the protein digestion process. Stomach acid is required to activate the digestive enzymes. There is also a resident population of bacteria here and some microbial fermentation does take place. As far as we know, the stomach does not absorb nutrients.

The Small Intestine

The small intestine digests and absorbs fats, protein, sugars, and starch. Digestive enzymes (which are like small scissors whose job is to cut up food) as well as bile from the liver cut these nutrients into small pieces so that they can be absorbed into the bloodstream.

The rate of passage through the small intestine is quite fast. It speeds up if you feed your horse large meals, as the stomach then loses its ability to slowly release food to the small intestine. When rate of passage is too fast, nutrient absorption is reduced as the small intestine doesn’t have time to do its work.

The Hindgut

The cecum and colon (made up of the dorsal colon and ventral colon) are collectively known as the hindgut. The hindgut is the centre for structural carbohydrate digestion. Structural carbohydrates, also known commonly as fibre, are digested in a process of microbial digestion. The hindgut is, in essence, a large fermentation vat. Your horse’s resident population of “good” fibre fermenting bacteria ferment the fibre from your horse’s feed to produce volatile fatty acids (VFAs). Your horse then absorbs these VFAs and uses them as a source of energy (calories).

The good bacteria in your horse’s cecum and colon play many roles in maintaining equine health. Plus the hindgut is also responsible for water and electrolyte absorption, which needs to be working properly to allow your horse to form normal fecal balls. For more detailed information on feeding for hindgut health please see https://feedxl.com/15-keeping-the-hindgut-healthy/

How is this related to equine health?

Well, in EVERY way! If you mess up your horse’s digestion, you really mess up your horse’s health. Colic in horses is the number one killer of horses worldwide. More than 90% of horses in some disciplines have gastric ulcers. Our studies found that almost 30% of horses in race training had hindgut acidosis, which is a severe imbalance of the bacteria in the cecum and colon.

As riders we also all struggle at some level with our horse’s behaviour. Science is starting to show us how shifts in gut microbial populations is tightly linked to behaviour.

All of these conditions affect the health and wellbeing of your horse plus they will cause problems like loss of appetite, weight loss, and poor hoof quality.

It is so important that we understand that the way we feed horses has a huge impact on the risk of these diseases and disorders. The most effective way of reducing the risk is by understanding the horse digestive process, and by feeding in a way that supports digestive health, rather than destroying it.

How does what and how we feed affect gut health?

When we feed our horses we need to take into account what the horse’s nutrient requirements are so that the feeds provided actually give your horse what he needs (and this is what FeedXL is designed to help you with!).

BUT, equally important is to consider how what you choose to feed will affect your horse’s digestive process, microbial population, and overall gut health.

Here are some of the ways what and how you feed can affect your horse’s digestive health:

  1. Long periods of time without feed – if you are feeding your horse in meals, and there are long periods (more than four hours) where he goes without something to eat, his stomach will empty and strong hydrochloric acid will start to accumulate. With an empty, highly acidic stomach, your horse is at increased risk of gastric ulcers (see https://feedxl.com/8-avoiding-gastric-ulcers/).
  2. Too much starch – starch is the main component of cereal grains. Research has shown that if you feed too much starch per meal or per day, the risk of gastric ulcers is increased (see https://feedxl.com/starch-ulcers-whats-the-deal/).
  3. Indigestible starch – if you feed cereal grains that have not been cooked prior to feeding, the starch is very difficult for a horse to digest in the small intestine. This means a majority of the starch from these ingredients will end up in the hindgut and can cause hindgut acidosis (see https://feedxl.com/18-feed-cooked-grains/).
  4. Not enough fibre – If you are not feeding your horse enough fibre, the good, fibre fermenting bacteria in the hindgut won’t have enough food to maintain a healthy microbial population. With fewer fibre fermenting bacteria, your horse can suffer from vitamin deficiency, loss of appetite, weight loss, diarrhea, poor hoof quality (increasing his need for specialized hoof care) and changes in behaviour. Low fibre diets are also a major cause of colic in horses. Low fibre intake also reduces saliva production which can increase the risk of gastric ulcers (see https://feedxl.com/38-the-importance-of-fibre/).

Top Five Tips for Feeding to Promote Digestive Health

Feeding in a way that properly supports the equine digestive process is not difficult. Here are the top five things you can do to keep your horse’s gut as healthy as possible:

Tip 1 – Feed Lots of Long Stem Fibre!

Long stem fibre, in the form of forages like pasture, hay, or haylage will encourage a lot of chewing and salivation, which will support the health of your horse’s stomach (reducing the risk of gastric ulcers). As long stem forages take longer for your horse to eat, they maximize the amount of time your horse will spend eating. This again reduces the risk of gastric ulcers.
The fibre will also feed the microbial populations of good bacteria in the hindgut to keep them healthy, and it will keep the hindgut full, reducing the risk of colic in horses.

Tip 2 – Feed in Small Meals

The rate of passage through a horse’s digestive tract is naturally quite fast. BUT, horses are trickle feeders. So they eat small amounts of feed, consistently over a 24-hour period. This means even though feed is moving relatively quickly, there are only small amounts of it passing through the small intestine at any one time to give it the best chance of digestion and absorption.

However, when we feed horses in large meals, twice per day, we suddenly create a situation where large amounts of feed are moving quickly through the small intestine. When this happens, less is digested and absorbed. So your horse becomes inefficient and needs to be fed larger amounts of feed to maintain weight. AND with components of the feed like starch ending up in the hindgut, gut health and microbial populations are also compromised.

The solution here is to feed in many small meals throughout a day. As a rule of thumb, horses should have constant access to forage. Any “hard feed”, particularly high starch feeds (>15% starch), should be fed at no more than 200 grams per 100 kg BW (0.2 lb per 100 lb bodyweight) per meal. Your horse’s feed label may specify starch content. If you are unsure you should contact the manufacturer.

Tip 3 – Minimise Starch

Feeding too much starch puts your horse at increased risk of gastric ulcers and hindgut acidosis. Plus high starch diets tend to be lower in fiber and may compromise the health and balance of bacteria in the hindgut.
My rule is if you can achieve calorie intake with fibre alone (i.e. hay, haylage, chaff, pasture and high energy fibres like beet pulp) you should do so. Grains should only be used where the horse can’t physically eat enough fibre to meet calorie requirements (as is sometimes the case if your horse is a broodmare or performance horse). Or where the horse has a large requirement for muscle glycogen to compete (which often only applies to racing thoroughbreds).
But remember, forage only will NOT be a complete diet. Always use FeedXL to check which nutrients (vitamins and minerals) are missing and top these up with a supplement or balancer pellet.

Tip 4 – Feed Cooked Starch

If you are going to feed starch from cereal grains like wheat, barley, corn (maize), and rice or any by-product ingredients like rice bran and wheat midds (bran/pollard) that come from these grains, you should make sure the grains are well cooked prior to feeding. Grains and grain-based feeds that are extruded, micronized, steam flaked, or boiled will contain starch that can actually be digested in your horse’s small intestine.

Feeding cooked grains will maintain your horse’s digestive health by keeping starch out of the hindgut, preventing hindgut acidosis, and supporting the good fibre fermenting microbial population.

Tip 5 – Watch Water Intake

Water is an essential component of the equine digestive process. When your horse doesn’t drink enough, the contents of your horse’s gut can become too high in dry matter and they’re at risk of deveoping impaction colic.

Dirty, foul tasting water, cold water, hot water, water in a place where the horse doesn’t feel safe (e.g. the back of a stable) or unfamiliar water can all discourage your horse from drinking enough water.

To ensure your horse is drinking enough, keep the water clean (if you wouldn’t drink it yourself then it’s not clean enough), keep the temperature moderate where possible and be prepared when you are traveling to keep familiar sources of water with you or have a familiar way of flavouring the water to keep your horse drinking when he is not at home. If you are concerned your horse is not drinking enough water, add some salt to his feed and this will increase water intake.

Healthy Gut, Healthy Horse

When feeding your horse, you must always consider the impact of what you are feeding and your feeding management on the digestive process. Such a huge part of equine health is determined by the health of the gut!



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!

Click here to join the FeedXL Horse Nutrition Facebook Group


Black horse on brown pasture

How Stress Affects Your Horse’s Gut

Stress! Did you know stress affects the gut? In pretty dramatic ways!

Prof John Pluske presented a talk at this weeks animal nutrition conference looking at the effect of stress on weanling pigs. Here are some photos from his presentation:

Pigs have a very similar gastrointestinal tract to horses so I often look at pig data when trying to solve problems where there is not enough horse specific information to base my research on.

Prof Pluske showed that stress negatively affects a weanlings pigs gut. With the guts ability to repair itself and it’s effectiveness as a barrier between gut and body both being damaged by stress. Essentially when a piglet is stressed the gut gets damaged. But it then can’t fix itself and it starts to leak.

Which seems relevant to horses. I am sure that we see this in horses too and with the similarities in gut physiology it seems logical… which means we need to be really aware of how we feed and how that impacts on gut health, particularly when a horse gets stressed.

Three things that are really important:

1. Feeding a fully balanced diet that meets all nutrient requirements so the gut has the nutrients it needs to remain intact.

2. Feeding lots of forage. Forage is high in fibre and supports the population of good bacteria in your horse’s gut. These bacteria are very involved in maintaining overall gut health; and

3. Feeding high quality protein. The gut has huge requirements for specific essential amino acids. These amino acids are used by the gut to repair and to produce protective mucus. To provide optimum levels of these amino acids you need to use ingredients with high quality protein.

Protein quality is so important for many reasons. To learn more read our post ‘Understanding Protein Quality’.



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!

Click here to join the FeedXL Horse Nutrition Facebook Group


Starch & Ulcers: What’s The Deal?

You may have heard it recommended that horses with ulcers should be fed a ‘grain-free’, low starch diet. It is believed that any starch may make ulcers worse. Or stop them from healing when the horse is being medicated to resolve ulcers. But is there any scientific basis for what has now become a popular recommendation? Let’s take a look!

Starch is fermented to volatile fatty acids (VFAs)

Like the rest of the horse’s gut, the stomach is full of bacteria. When grains AND forage enter the stomach, they are partially fermented. During fermentation, the bacteria produce volatile fatty acids. These VFAs are the same as what is produced in the hindgut during fermentation there. So they are not harmful to the horse. In fact they are beneficial.

Thing is though, in the stomach, they get mixed with the hydrochloric acid from the stomach and become ‘nonionized’. In this state, they can enter the epithelial cells of the upper part of the stomach, causing them to become inflamed, and swell, and ultimately make the stomach wall lining more prone to ulceration. This is what they understand to happen in pigs.

So everything you feed a horse will be partially fermented in the stomach. We do know however, that when we feed a grain based, high starch ingredients, higher levels of VFAs are produced. But does it increase the risk of gastric ulcers? Not necessarily.

Lucerne + grain = less ulcers than grass hay

In a study where horses were fed either lucerne + grain OR grass hay only, there was significantly higher levels of VFA in the stomach contents of horses fed lucerne + grain. BUT, the horses on this diet had less severe and fewer gastric ulcers than the horses fed the grass hay only diet. Despite the higher level of VFAs, horses on the lucerne + grain diet had a higher pH (less acidic) for 5 hours after feeding when compared to the grass hay only diet 1.

The researchers in this study suggest the high protein, high calcium characteristics of both the lucerne hay and the ‘grain’ (unfortunately, they do not specify what the grain was except to say it contained over 7 g/kg of calcium and was almost 15% protein, so it must have been a fortified commercial feed) created a buffering effect in the stomach and were able to keep the pH higher.

So here, the starch did increase VFA levels, but the diet containing the grain was also effective at keeping gastric pH higher. Combined, there was a protective effect against ulcers.

In a second study2, researchers found that of horses fed lucerne plus a commercial pelleted feed, 8% developed ulcers. Compared to 75% who developed ulcers when they were fed the same pellet, but with grass hay. In this same study, horses that started with existing ulcers all improved their ulcers scores by more than 2 when fed lucerne + pellet. But on the grass hay, only 2 out of 12 horses showed healing to the same degree. So it does appear lucerne is protective. And that feeding grain/starch doesn’t automatically mean a horse will be prone to ulcers.

What about high fibre versus low fibre?

We tend to think that a high fibre diet is always going to be better than a low fibre diet for minimising gastric ulcers. And there are varied reports in the literature. Research from the UK3 reported that a low fibre, high concentrate (32% starch pellet) diet had a lower number and severity of lesions versus a high fibre, low concentrate diet. Odd right!

The fibre fed during this study was ryegrass haylage. A trend is starting to appear with grass forage and a higher risk of ulcers! What we don’t know is why? Researchers in Denmark reported that horses with straw as their only source of forage had a higher risk of ulcers4 which may give some clues. Perhaps there are nutrients required for maintaining gut wall integrity that grass hays and straw are unable to provide.

The important point here is to realise that just feeding lots of forage is not enough to protect a horse from ulcers. And to recognise that adding grain to diets is not a risk factor in itself. It comes down to which forages are fed and how much grain/starch is fed AND how feeding is managed.

How much starch is OK?

The studies reported above show that grain can be fed without causing ulceration. So starch is not a simple ‘Cause & Effect’ with gastric ulcers. Or in other words, when it is fed in a certain way, it can be fed without causing ulcers. And can even be fed in a way to allow ulcers to heal. But is there a limit to how much starch you can feed?

The answer is YES! In a large study, 201 Danish horses from 23 different non-racing stables were scoped for ulcers. 53% of horses were reported as having an ulcer score of more than 2, with most of these occurring in the upper part of their stomach4.

Two risk factors related to the amount of starch fed were reported in this study;

  1. Feeding more than 2 grams of starch per kg of bodyweight per day (equivalent to 2 – 3 kg of a complete feed/day for a 500 kg horse, depending on the feeds starch content) doubled the risk of ulcers; and
  2. Feeding more than 1 gram of starch per kg of bodyweight per meal (roughly equivalent to 1 – 1.5 kg of a commercial complete feed per meal for a 500 kg horse, depending on the starch content of the feed) increased risk by more than three times.

So some starch it seems is perfectly OK. But there is a limit to how much should be fed ‘per day’ and ‘per meal’.

Feeding grain based feeds carefully is a huge consideration in managing the risk of ulcers. If your horse needs more energy than can be provided by the amounts of grain based feeds specified above, you should look at feeding oils or high energy fibres to meet the rest of your horse’s calorie requirements.

Does starch cause ulcers?

Too much starch increases the risk of ulcers. But when fed in a well put together diet, research has shown that diets containing grains resulted in less ulcers than grass hay only diets. So starch, itself, doesn’t appear to cause ulcers.

My horse is prone to ulcers. What should I do?

Good question! Here are my top tips on feeding a horse prone to ulcers:

  1. Feed lucerne hay – lucerne has been shown to buffer the stomach well and is protective against ulcers. It even seems to help them heal.
  2. Feed lucerne as chaff or haylage with your grain based feeds – this seems to help negate the possible negative effect of starch when it is fermented in the stomach.
  3. Feed lucerne hay before you ride – working horses on a full stomach is CRITICAL for preventing ulcers. The fibre stops the acid splashing around and the saliva created while chewing the hay helps to buffer the acid in the stomach. Using lucerne has the extra positive benefit with the buffering effect from the lucerne itself.
  4. Feed lots of forage – the more forage in the diet the better. It makes a horse chew longer, create more saliva and keeps the stomach full of fibre to help stop acid from the lower part of the stomach splashing up onto the top part and creating ulcers.
  5. Don’t allow more than 5 hours between meals – the longer the intervals between meals, the higher the risk of ulcers5. So make sure your horse is eating at least every 5 hours. For horses particularly prone to ulcers, keeping time without food as short as possible (no more than 2 hours) is advisable.
  6. If you feed grain based feeds, keep the amounts small – don’t exceed 1 gram of starch per kg of bodyweight per meal. The amount of pellet/sweetfeed/cube/grain you can feed per meal depends on the starch content of the feed. The table below shows you maximum amounts that can be fed per meal of a feed, based on its starch content, for a 500 kg horse. If you are unsure of your feeds starch content, don’t exceed 1.5 kg of feed/meal (for a 500 kg horse).


Starch Content (%) Maximum Amount/Meal for a 500kg Horse (kg)
20 2.5
30 1.7
40 1.25
50 1


  1. Make sure horses ALWAYS have access to water – water deprivation has long been known to increase risk of ulcers. So allowing constant access to water is important to reduce the risk of ulcers.

Should I go grain-free?

While the studies above show us that feeding grains, in diets that also contain lucerne can result in ulcers resolving, if you are more comfortable going grain-free then it is certainly an option. Using high quality, grain-free products that are high in protein and fortified with calcium are likely going to work well for a horse prone to ulcers. As far as I can see there are no studies to confirm this… something for future research to work on!

It is just important to remember that this is not essential. Grain based feeds can be used, as long as they are used carefully.


  1. Nadeau JA, Andrews FM, Mathew AG, et al. Evaluation of diet as a cause of gastric ulcers in horses. Am J Vet Res 2000;61:784-790.
  2. Lybbert T, Gibbs, P., Cohen, N., Scott, B., Sigler, D. Feeding Alfalfa Hay to Exercising Horses Reduces the Severity of Gastric Squamous Mucosal Ulceration. AAEP Proceedings 2007;53.
  3. Boswinkel M, Ellis A, Sloet van Oldruitenborgh-Oosterbaan Mm. The influence of low versus high fibre haylage diets in combination with training or pasture rest on equine gastric ulceration syndrome (EGUS). Pferdeheilkunde 2007;23.
  4. Luthersson N, Nielsen KH, Harris P, et al. Risk factors associated with equine gastric ulceration syndrome (EGUS) in 201 horses in Denmark. Equine Vet J 2009;41:625-630.
  5. Luthersson N, Nielsen KH, Harris P, et al. Risk factors associated with equine gastric ulceration syndrome (EGUS) in 201 horses in Denmark. Equine Veterinary Journal 2009;41:625-630.


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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Dark brown horse looking bavk

How to Treat Free Fecal Water

Do you have a horse that has water that runs out of the anus before, during or after he poos?

This condition now has a name! Free Fecal Water, or FFW. And also, happily it now has some research behind what may cause it as well as a potential treatment.

If it is something you struggle with, read on!

There were multiple presentations on free fecal water at the EEHNC conference. Here is a summary of the main points:

What is Free Fecal Water?

Free Fecal Water (FFW) is a condition in which horses produce normal feces, but before, during or after defecation, free water runs out of the anus.

There appears to be no effect on general health associated with the condition, but it can cause skin irritation and it becomes a management (and appearance) issue for you as the owner.

Causes can include abrupt changes in forages, a change from hay to haylage and use of large amounts of high-moisture wrapped forages. Horses that have suffered previous bouts of colitis, geldings and paint horses are at higher risk. The association for geldings and paints is thought to be due to their position in social hierarchy and higher levels of stress.

Dental health and parasitic infections/fecal egg counts have not been found to be related.

There may be some sort of motility disturbance, with either increased gut motility or abnormally strong gut contractions, and inflammation of the gut involved, all reducing the hindguts ability to absorb water.

What can you do about Free Fecal Water?

It was recommended that management of free fecal water focuses around proper ration formulation to provide a balanced diet using ingredients that will support a healthy gut environment (we of course recommend FeedXL to help with this), as well as good feeding management to provide regular small meals and constant access to forage. It was also recommended to keep starch at a maximum of 1 g/kg bodyweight per meal.

You should also pay attention to the type of forage and fibre being fed, being sure to incorporate fibres that have good water holding capacity. Grass forages for example will hold more water toward the end of the hindgut than alfalfa/lucerne forage or a superfibre like beetpulp will hold.

The final point discussed was potential treatment using a fecal transplant from a healthy horse. In a study with 14 horses with free fecal water, all showed improvement 3 days after being treated via fecal transplant and 2 months after treatment, 7 of the 14 horses had had no re-occurrence of the condition. (Theelen, unpublished). Laustsen et al (2018) reported a second study in which 10 horses with FFW were treated using fecal transplant (or fecal microbiome transplant, FMT). Within a week of treatment their free fecal water score dropped in severity and remained low for the entire 12 month study, supporting the use of fecal transplant for treatment of these horses.

The researchers were careful to point out that all other possible causes of this condition must be ruled out prior to treatment via fecal transplant. They suggested radiographing the abdomen to look for sand, a full rectal exam, testing for parasites, ruling out irritable bowel disease and scoping for gastric ulcers.

The method for the fecal transplant treatment given was as follows:

  1. Place horse on omeprazole (full treatment dose) for a couple of days prior to fecal transplant (this will just cut the acid production in the stomach and make it more likely that the bacteria will make it through alive). GREAT IDEA!!
  2. Take 500 grams of fresh feces from a suitable donor (one who is on a high forage diet with a healthy hindgut and parasite free).
  3. Gently mix the feces in 2 litres of luke warm water, sieve to remove large particles and then add 100 grams of grass or other fibre only pellets (make sure they are grain free with a very low starch and sugar content). Other options would be alfalfa, soybean hull, beet fibre or lupin hull pellets.
    At this stage be careful not to shake the mixture and run a sieve through the mixture to collect large particles as opposed to pouring the mixture through the sieve… this will help to keep the manures exposure to air as minimal as possible because oxygen will kill many of the good bacteria and these are the ones we want very much alive!
  4. Administer via gastric intubation (this is a veterinary procedure and must be carried out by your veterinarian).

If you try this treatment on your horse we would love to know the outcome! I have had much success over the years using fecal transplant in horses with chronic diarrhea, but don’t have experience using it with these free fecal water horses. And the omeprazole step is a brilliant idea, I’d always worried about the poor bacteria getting through the highly acidic stomach, so makes perfect sense to make the stomach environment a little friendlier for them and I imagine it will only serve to improve the effectiveness of the treatment.

Reference: Mathijs et al (2019) Free Faecal Water: What do we know and can equine faecal microbiota transplantation be used to manage this issue? European Equine Health and Nutrition Congress, Utrecht, The Netherland



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

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Horse on summer pasture

What You Should Know About Anaerobic Fungi

Anaerobic Fungi! These little critters live in our horses’ hindguts! And they are responsible for an estimated 30 to 40% of the fibre fermentation that occurs in there! So as well as thinking about how diet might affect our horse’s hindgut bacterial populations we also need to think about how it might affect their anaerobic fungal populations!

Problem is, we know so little about them that we don’t know what is good and what is not so good for them. Information on what we know so far was presented at EEHNC by the incredibly passionate researcher Dr Joan Edwards. Joan described the fungi as having potent fibre degrading enzymes, giving them an important role in a horse’s digestion process.

The fungi can survive outside the horse’s gut too, and are seemingly resistant to both oxygen (which kills many anaerobic bacteria that live in the hindgut) and desiccation (drying out). This makes me wonder if they are part of the reason why my horses will seek out specific dry manure piles and eat them on occasion… maybe?!

Anyway, there is some research published (e.g. https://www.researchgate.net/…/329954798_Anaerobic_fungal_c…)

And more research to come (https://www.wur.nl/en/project/Equine-Anaerobic-Fungi.htm)… so watch this space as we keep learning more.

In the meantime while we figure out how to look after these fungi, I suspect feeding in the way that will look after the bacteria in a horse’s hindgut will also look after the fungi… so keep your horse’s diet high in low fructan forage, keep grain/starch out of the hindgut by feeding only well-cooked grains where necessary and in as small meals as possible and make changes to the diet slowly.

I love info like this as it is exciting to know we are always understanding horses better. Part of me though is thinking great, yet another thing we have to think about!?



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