Posts

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’.

Questions? Comments?

Click here to join our Horse Nutrition Forum on Facebook

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.

References

  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.

 

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.

Questions? Comments?

Click here to join us on our FeedXL Horse Nutrition Forum on Facebook

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! ?

Questions? Comments?

Click here to see this post on the FeedXL Facebook Page

Too Much Salt Might Be Killing Gut Bacteria

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.

The paper is here if anyone would like to read it in more detail: https://www.nature.com/articles/nature24628

Questions? Comments?

Click here to see this post on the FeedXL Facebook Page

Gastric Ulcer Medications and Their Effect on Digestion

Q: Does gastric ulcer medication reduce nutrient digestion in horses?

Someone asked me this in a recent seminar and it reminded me that when I was studying during my PhD tenure we had looked at the effect of pre-incubating grains in equine stomach fluid on the digestion of starch from those grains.

And what we found was that starch from grains that were exposed to equine stomach fluid before being digested by small intestinal enzymes was between 17% (extruded rice) and 104% (cracked triticale) MORE digested than starch that wasn’t exposed to the stomach fluid. So the stomach fluid was having a definite positive influence on the digestion of starch.

What we can’t say from this research was how much of this increased starch digestion was due to the stomach acid and how much was due to the protein digesting enzymes the are present in stomach fluid that would be starting protein digestion and making access to the grain starch easier for the starch digesting enzymes in the small intestine.

The thing to remember though is that the protein digesting enzymes in a horse’s stomach fluid rely on the stomach acid to activate them. So regardless of whether the improved digestion was due to the acid itself or the protein digesting enzymes, if you stop acid production using ulcer medications you will lose both the acid and the enzymes.

So, if we use medications like ranitidine and omeprazole to reduce gastric acid secretion in horses we are very likely reducing the digestion of at least some nutrients further down the gastrointestinal tract.
What to do??? Well, if your horse has ulcers this is by far the most important consideration, you need to medicate to get rid of the ulcers as quickly and as effectively as you can.

BUT, once the ulcers are gone it is recommended you use good management practices to keep your horses chewing, their stomachs full and buffered with saliva and their minds calm instead of constantly using medication to prevent ulcers. That way you are allowing their gastrointestinal tract to function the way it was designed (albeit I would love the opportunity to redesign parts of their gut!) and allowing the digestion process to be as effective as possible.

More info on feeding to prevent ulcers in our article ‘Avoiding Gastric Ulcers’ here https://feedxl.com/8-avoiding-gastric-ulcers/

Happy to share the method for the in vitro assay used to conduct this work with anyone who would like the details!

Click here to see this post on the FeedXL Facebook Page

Gut Bacteria and Human Health

We talk a lot about a horse’s gut bacteria and how they impact health… have you ever stopped to think about your gut bacteria and how they might be influencing your health?? This relatively new area of science quite literally blows my mind. These tiny critters control us in so many ways and have such a massive impact on our life that it is truly worth thinking about how what you eat affects them (and then how they affect you).

Here are a few very quick bits of info that are quite amazing… you ready?!

1. Bacteria in your body outnumber your human cells by 10 to 1, so in actual fact, we are 10 parts bacteria, 1 part human.

2. Bacterial DNA in our body outnumbers our human DNA by 100 to 1, so in that respect we are only 1% human (Don’t think about that too much!!)

3. Bacteria like to tell us what to eat. Certain foods are their favorites so in order for them to survive, they will make us go and eat their favorite foods! This is OK if you have a nice healthy population of fibre/vegetable loving bacteria in your gut. But it becomes an issue when you have accidentally bred up a sugar or fat loving bunch of microbes. Next time you are craving sugar or fatty food you can probably blame your bacteria! In saying that, if you starve the ones you don’t want in there (e.g. stop eating sugar) the cravings should lessen!

4. Bacteria produce mood altering hormones like dopamine and serotonin. Studies suggest half of these hormones in our body come from our intestine! Get the wrong bacteria and you could very likely be in the ‘wrong’ mood!

5. Bacteria can reduce or increase anxiety. In mice, taking the gut bacteria from nervous mice and introducing them to calm mice made the calm mice anxious! Scary huh!!

This list could go on (and on… and on!). There are known relationships between diseases like asthma and Type 2 Diabetes and gut bacteria for example. Suffice to say they are important little critters and probably have far more of an influence on you (and your horse) than you realise.

Eat well! Keep those bacteria healthy … I can’t help you much here (other than eat more real food and less junk) but certainly when it comes to feeding your horses, always think about how what you are feeding is affecting their gut bacteria. If you have time, have a read of our article on feeding for hindgut health!
https://feedxl.com/15-keeping-the-hindgut-healthy/

And if you’d like to read some more about all the amazing interactions you have with your own bacteria, this article is good! https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270213/

Enjoy!! Nerida

Click here to see this post on the FeedXL Facebook Page

The Link Between Regular Forage Meals and Gut Health

Poet and I (Nerida) headed out a few weeks ago to do some real work mustering sheep (not that we did anything useful, we were just along for the ride!). There were 5 of us on horses, saddled up by 6:30 am and in incredibly steep, rocky, tough (but stunning!) terrain for 6 hours. At various points we dismounted and slid (feet sideways) down parts of the mountainside because it was too steep to ride. Sheep were tripping and rolling down the hill (amusing! but gives you an idea of how steep it was!!).

Anyway, here is me, very conscious of gastric ulcers, giving my horse lucerne/alfalfa as I saddled up, letting him pick what grass we could find while out riding if we were stopped for any time so he at least salivated a little bit and immediately giving him water and more lucerne/alfalfa on return to where we had saddled up… meanwhile stifling my panic at watching the other horses eating nothing and trying not to think too much about what was going on in their stomachs.

I asked one of the guys, an experienced horseman, if he worried about ulcers, and it soon became clear that there was no understanding of how a horse’s stomach worked and the negative impact of not feeding them for such long (long!) periods of time (his horse had a couple of hours trip home).

I also asked recently at a seminar who could confidently sketch a horse’s gut or explain how it works and no-one was able to. And I get this… I had no idea what a horse’s gut looked like or how it worked the entire time I rode in my pre-nutritionist life!

The thing is, a horses stomach never stops secreting gastric acid. So even when your horse is not eating it is filling the lower part of its stomach up with acidic gastric juices. While the stomach is full this isn’t an issue as the dense matt of fibre in the gut will stop the acid from splashing around and burning the unprotected lining of the upper section of the stomach.

Problems start though when horses are off feed for long periods like this and end up with a pool of acid and an empty stomach. Combine that with the movement of being ridden and you get acid splashing up and quite literally burning holes (causing ulcers) in the top part of the stomach.

So here is my plea! Please help us to educate people on how a horse’s stomach works and what they can do (really simple things) to keep their horse’s stomach and therefore their horse healthy and pain free. Share this article on Avoiding Gastric Ulcers with them and have them understand that a horse’s stomach should never be empty and that as much as is practical you should never work a horse on an empty stomach.

Thank you!! From us and from all of the horses who will be so much better off when their owners understand how they work just a tiny bit better.

The Impact of Proton Pump Inhibitors on Gut Bacteria

An interesting read about the impact of proton pump inhibitors (PPI) like Omeprazole (the major drug we use to treat equine gastric ulcer syndrome) on the gut bacteria in humans! https://gut.bmj.com/content/early/…/12/09/gutjnl-2015-310376

While these drugs are a huge help in setting up an environment in the equine stomach where ulcers can heal, they are overused in many horses (some racehorses are never taken off these drugs) to prevent ulcers in place of management systems that will reduce a horses risk of ulcers (like feeding a forage meal to fill the stomach prior to work).

Makes me wonder what PPIs may be doing to the equine gut bacterial populations… one study I can find (https://onlinelibrary.wiley.com/doi/pdf/10.1111/eve.07_12792) shows no impact on equine fecal bacterial populations, but use of omeprazole in these horses was only short term and the study doesn’t specify the dose used. The fecal microbiota also aren’t necessarily reflective of what is happening further up the gastrointestinal tract.

Something to keep in mind if you have a horse on a PPI medication long-term. Needs some more research!

Click here to see this post on the FeedXL Facebook Page

How to ‘Measure’ Gut Health

Gut health! It’s so important but also really hard to ‘measure’. One way to get a bit of an indication of what your horse’s hindgut health is like is to check faecal pH.

A healthy hindgut will stay at quite a neutral pH, close to 7. At this pH the good fibre fermenting bacteria will be living happily ever after and doing an amazing job of digesting fibre for your horse.

A high pH (over 8) may indicate that there is not a lot of fibre fermentation happening in the hindgut for some reason, while a low pH (less than 6.5) may indicate that there is too much fermentation of starch and sugars happening. The good fibre fermenting bacteria don’t like living in these lower pH conditions and will be starting to shut down. If pH goes below 6.2 you can be almost certain that a lot of your good fibre fermenting bacteria will be starting to die and your horse will lose the ability to digest fibre (which then causes all sorts of problems including weight loss and vitamin deficiency).

So if you want to do a quick check on hindgut health, grab a ‘soil pH test kit’ (google that, you will find plenty of options for inexpensive kits) and use it on a fresh pile of your horse’s manure. You might find that pH is just right, or you may just find that something is a little out of kilter and you need to adjust the diet to get it back to a more neutral pH.

Have fun! I spent three years of my life measuring faecal pHs, fond memories! ?

Click here to see this post on the FeedXL Facebook Page

Enzymes, What Do They Do for Your Horse?

When a horse eats, much of its feed is made up of LARGE carbohydrate, fat and protein molecules. The horse can only absorb tiny little molecules from its gut (because if big stuff was able to cross from the gut into your horse’s body all sorts of bacteria, toxins and general muck would pass into the body and cause disease havoc!).

So before absorption from the small intestine can occur, the big stuff must be chopped up into little stuff. And it is enzymes in your horse’s gut that do this chopping.

It is easiest to think of digestive enzymes as little pairs of scissors. Let’s look at starch as an example. Starch (found in cereal grains like barley and corn/maize) is made up of lots of glucose molecules, all joined together. The job of the starch digesting enzymes in your horse’s small intestine is to cut starch into single pieces of glucose. Then it is the glucose that your horse is able to absorb.

Each nutrient has its own specific set of enzymes in your horse’s small intestine. So there are specific enzymes to digest/chop up starch, protein and fats/oils.

To learn more about enzymes and your horse’s digestive system, read https://feedxl.com/31-the-gastrointestinal-tract/

Click here to see this post on the FeedXL Facebook Page

© FeedXL