Tag Archive for: grains

Starch & Ulcers: What’s The Deal?

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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.

 

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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5 Ways One Balanced Diet Can Be Better Than Another

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We recently had a member of our nutrition forum ask ‘Can one balanced diet be better than another, or is the key point that it is balanced?’

This is probably the best question I have ever been asked! And the answer is absolutely YES! One balanced diet can be better than another!

BUT, before I explain why, I just want to say that diets balanced using FeedXL will be 1000 (or more) times better than a diet that is unbalanced and not meeting a horse’s basic nutrient requirements. So take heart that if your diet is balanced on FeedXL, you are way ahead in keeping your horse healthy.

So balanced diets that meet all of your horse’s known nutrient requirements are better than unbalanced diets that do not meet requirements.

But, one balanced diet can certainly be better than another.

Here are 5 examples of what makes one diet better than another:

 

Factor OK Option Better Option Why is this better?
Forage Amount Diet just meets the FeedXL minimum forage requirement. Forage is a major component of the diet and is used to meet as much of a horse’s daily digestible energy requirement as possible. The more forage in a diet the better your horse’s gut health will be. If you feed a balanced diet but your horse’s gut is unhealthy, your horse’s overall health will be limited.
Forage Variety You feed only one or two different types of forage. For example Teff hay and alfalfa/lucerne chaff or pellets. Your forage (pasture, hay, chaff, forage pellets or cubes) is made up of several different plant species. For example, your pasture has 3 different grass species plus clover, and you feed a mixed meadow hay plus alfalfa/lucerne chaff. Lots of forage variety gives good fibre variety and this supports a diverse and robust hindgut microbiome that is less prone to disturbance and more able to provide the nutrients, immune function and hormone support a horse needs. PLUS…while we know a lot about many nutrients a horse needs (like copper, vitamin E etc) there are MANY nutrients (like the omega fatty acids and most of the essential amino acids) that we know your horse needs. We just don’t know how much he needs. Feeding a large variety of forages improves the chances you will meet requirements for all of these nutrients we don’t understand very well yet.
Uncooked Grains The ONLY OK option for uncooked grain is oats. ALL other grains must be cooked. They are definitely not OK to feed uncooked. All grains are easier to digest when they are cooked (boiled, extruded, steam flaked, micronized). In fact you must only feed barley, corn and rice if it has been cooked. Feeding any of these grains uncooked is going to make your horse sick. The starch from cooked grains can be almost fully digested in your horse’s small intestine. Meaning less starch is allowed to get into your horse’s hindgut to feed the ‘bad’ bacteria. If you do feed raw grains, your horse’s hindgut will become acidic, bad bacteria will flourish and your horse’s gut and overall health will suffer.
Using Oil All oils are ‘safe’ and all provide the same amount of digestible energy in a diet. But, some oils like sunflower and corn oil are extremely high in omega 6 and can unbalance your horse’s omega 3 to 6 ratio. Canola oil provides a good blend of omega 3 and 6 fatty acids and is particularly useful in diets that contain no grain to provide the omega 6 your horse will need. Flax/Linseed oil is very high in omega 3 and is super useful in high grain diets to balance the omega 3 to 6 ratio. If you feed too much omega 6 in a diet it can result in excessive inflammation. Choosing your oils to match your diet (a little like choosing your wine to match your meal) means you will meet omega 3 and 6 requirements and keep the ratio between the two balanced.
Protein Quality As long as you meet your horse’s protein AND lysine requirement in FeedXL you will be doing a good job of providing enough protein and essential amino acids. BUT, not all proteins are created equally. Cottonseed meal, for example, contains lysine, but 60% of it is unavailable for absorption. Or flax/linseed meal is high in protein but it is low in essential amino acids. Choose premium quality proteins for your horse’s diet so that when FeedXL shows you that crude protein and lysine requirements are met, you also have an excellent chance of meeting all requirements for the essential amino acids. This includes choosing things like a component of soybean in preference to an unnamed ‘vegetable protein meal’ and/or using some alfalfa/lucerne together with your grassy forages. When you feed better quality protein you will get more muscle! When you are able to use high-quality sources of protein that meet your horse’s essential amino acid requirements you will have a better chance of 1. Providing enough of the amino acid ‘Leucine’ to switch muscle building on; and 2. Providing the building blocks needed to actually build muscle.

 

So if you want the best possible diet, here are my top 5 tips:

  1. Feed as much forage as possible to meet digestible energy requirements.
  2. Use as many different types of forage as possible.
  3. Never feed uncooked grains!
  4. Use oils that have an omega 3 to 6 profile that will complement your horse’s diet; and
  5. Use high quality proteins.

If you can do all of that AND have a balanced diet, your horse will be ready to take on the world!

 

 

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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Grain Free Horse Feed: What Does it Actually Mean?

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It can be a bit confusing to get to the bottom of what grain free horse feed really means, especially when you see it printed on a feed bag derived mostly from grain products. In this post we’re unravelling the technical classification of ‘grain free’, and helping you find a suitable feed, even if your horse is grain-intolerant.

How we classify ‘grain free’ in FeedXL

Here at FeedXL we classify feeds in our database as being either ‘grain-free’ or ‘contains grain’, so that if one of our members clicks that their horse is ‘grain intolerant’ they will see the feeds and supplements available to them listed either in black (meaning it is grain free) or ‘red’ (meaning it contains grain).

Occasionally though we are questioned about certain feeds that we have classified as ‘contains grain’ and are sometimes told we have them classified incorrectly because the feed only contains a grain by-product like wheat midds (or bran, pollard, broll, millmix, millrun… many names for similar ingredients).

So does containing a grain by-product mean the feed should be classified as ‘grain-free’ or as ‘contains grain’?

Our position on ‘grain free’ horse feeds

There are companies who make feeds that are almost 100% wheat midds or rice bran and splashed all over the packaging it says grain free! Technically they aren’t but they are classified like this because they only contain PARTS of a grain and no whole grains.

The issue (for us and for horses) is that these by-products, while not whole grains, are derived 100% from grain and still have many of the same characteristics (same proteins, still high in starch, albeit not as high as the whole grains etc). So if someone really needs to avoid wheat or starch for example and they find one of these ‘grain-free’ feeds made with wheat midds there is an issue born from a technical classification that doesn’t tell the full story.

Calling feeds with wheat midds or rice bran ‘grain-free’ would be like saying soybean meal is ‘soybean free’ just because it no longer contains any whole soybeans. Or saying copra meal is coconut free because there are no whole coconuts. Technically yes, they don’t contain the entire original ingredient but for us (and thus FeedXL) we are just not comfortable saying something is grain free when it isn’t.

Imagine the consequences in human foods if manufacturers were allowed to say ‘wheat free’ if a product only contained midds or peanut free if it only contained peanut oil. Much more serious in humans we know but just using them as examples to make the point.

Keep an eye on starch and sugar content!

For horses, what starts to become more important in many cases though is the actual level of starch and sugars in a product. So if we were looking at a diet for a laminitic pony and considering using a feed with wheat midds in it, the important thing is how much starch are those midds contribution to the final feed. If total starch and sugar content is still below 10 to 12% then it should be OK. If it isn’t, then it doesn’t matter how much a feed might claim to be grain free, its analysis says it won’t be safe based on its actual starch and sugar content.

Here at FeedXL, we firmly believe we need to stop confusing horse people with technical classifications to allow loophole claims on feed packaging. This is just our opinion but we have seen pretty devastating effects in horses because they have been fed a feed claiming to be grain-free and therefore their owners believed it would be safe to feed. It is something that shouldn’t happen!

How FeedXL can help you choose the best feed for your horse

When you click ‘grain-intolerance’ in FeedXL you will be able to see which feeds are truly grain free and which are not. If you select that your horse has laminitis or insulin resistance you will see the feed ingredient options classified instead by starch and sugar content.

If you want to save yourself some time finding suitable feeds for horses with conditions that require either grain-free or low starch and sugar feeds give FeedXL a go! Check out our plans and pricing here and start your free trial today!

 

 

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 You Should Know About Phosphorus and Phytate

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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!!

 

 

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

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Is Grain Free/Low Sugar, Low Starch Always the Way to Go for Horses?

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Feeding grain free diets has grown in popularity in the last 10 years and there are certainly many benefits. BUT, need it always be the way to go? The answer is, it depends, but often no.

Horses with conditions like laminitis, PSSM tying up, PPID/Cushing’s, equine metabolic syndrome, insulin resistance etc MUST be fed a low sugar, low starch (or low non-structural carbohydrate; NSC) diet. Usually, to achieve low enough starch and sugar levels, these diets need to be grain free. One of the things FeedXL is great for is to help you sort out which feeds, forages and supplements are safe (low in starch and sugars; NSC) or not safe to feed horses with these conditions.

But for horses that don’t need low sugar, low starch diets to control diseases, as long as grain is FED SAFELY, grains can form a very valuable part of a ration! They are economical compared to high energy fibres like beet pulp (which are expensive in comparison), they provide a source of glucose that horses in heavy work can use to readily replenish muscle glycogen supplies, and they are palatable… horses love grains, so keeping horses in hard work eating on grain based feeds tends to be relatively simple provided the recipe is good!

So, as long as grains are well cooked (with the exception of oats which can be fed uncooked) and as long as you feed them in small meals (no more than 0.5 kg/100 kg BW, 0.5 lb/100 lb BW) they can form a very useful part of a horse’s diet. These are HUGE ‘as long as’ statements too… feed grains in the wrong way and things WILL go horribly wrong. But that is another story for another day.

The moral of this story is don’t fall into the trap of one-size-fits-all when it comes to grain free. 

There is more info here on why we cook grains for those of you who would like the details: https://feedxl.com/18-feed-cooked-grains/

 

 

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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How Long Should You Boil Barley or Corn?

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Cooking cereal grains before you feed them to your horse is very important. It improves how easy they are for your horse to digest and drastically reduces the chance of them causing negative effects in your horse’s hindgut.

So if you are cooking your own grains, how long should you cook them for? Are you ready for the answer, it is really very technical …

Cook grains until they are soft and squishy!

Just cook them with lots of water until they are easy to squash between your thumb and index finger. Once they are soft like this their digestibility will be very good.

Want to know why you should cook grains before you feed them? It is all here: ‘Grains for Horses: Cooked or Uncooked?‘

P.S. Don’t just soak them until they are soft, this won’t improve digestion… you must use heat!

 

 

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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Benefits of Oats for Horses

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It has been known for a very long time that oats and horses just seem to get along well. Of all of the cereal grains we can feed to horses, oats is the only grain that can be fed safely without being cooked. Why? Horses are able to digest a large portion of the starch that oats contains in their small intestine. Which means only small amounts of starch will be deposited into the hindgut.

Oats vs Other Grains

If we feed corn or barley uncooked, only about 25% of the starch they contain is digested in the small intestine. The rest is fermented in the hindgut.

When starch gets into the hindgut, starch fermenting bacteria ferment it very quickly and cause a build-up of acid and create a condition called hindgut acidosis which has all sort of negative consequences for your horse (including changes in behaviour and laminitis). The balance between fibre fermenting and starch fermenting bacteria is also put out of balance… the ‘good’ fibre fermenting bacterial populations are reduced while the less desirable starch fermenting bacteria increase in numbers.

All of this we have known for a while. More recent research however (Harlow, 2015) has also shown that corn starch is potentially more of a problem in the hindgut than oat starch. This researcher incubated corn and oat starch in test tubes with faecal material from horses and found (briefly) that corn starch caused a significantly greater increase in starch fermenting bacteria than the oat starch and gave rise to higher lactic acid production.

Double Safety Catch in Oats

So oats seems to have a double safety catch built in for our horses. First, most of its starch appears to be digested in the small intestine. Second, if some starch does end up in the hindgut it appears less likely to upset the hindgut bacterial populations present there, which should mean it allows your horse to maintain a healthy population of the ‘good’ fibre fermenting bacteria.

So if you need to feed a grain and either don’t have access to or don’t like ‘cooked’ grains for some reason, go for oats, they are the safest choice for your horse.

 

 

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

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Grains for Horses: Cooked or Uncooked?

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While a lot of time is spent focussed on horses that can’t eat grain in their diet, cereal grains such as oats, barley, triticale, corn, rice, rye, sorghum and wheat form a valuable component of many horse’s rations. Selecting the most digestible grain based feed however can be confusing, with uncooked grains like whole, cracked and crushed grains being available as well as cooked grains like extruded, micronised, steam rolled or steam flaked and pelleted grains.

The question is, which form of grain is best for your horse, cooked or uncooked?

Why we cook grains

Grains are fed primarily as a source of energy in a horse’s diet and that energy is derived mainly from the white starch found in the centre of the grain. For the horse to obtain the energy from the starch it must be digested by enzymes in the small intestine.

But digesting the starch to extract the energy is not easy for the horse because it is “packaged” within the grain in a way that makes it difficult for the horse to get to. The reason grains are cooked is to make access to the starch a lot easier for the horse.

How starch is “packaged”

Starch is simply many glucose molecules all bonded together and bundled up into starch granules. These starch granules are then embedded amongst protein in a structure known as the protein matrix (Figure 1).

 

Figure 1: A scanning electron micrograph of the middle of a barley grain showing the starch granules embedded within the protein matrix. The starch granules are the large round objects.

 

The starch granules, embedded in the protein, are then encased within individual endosperm cells and protected by a cell wall. Many of these cells are packed tightly within the grain’s starchy endosperm (the white bit found in the middle of a grain). And the endosperm itself is protected by the aleurone layer and finally the entire structure is covered by the seed coat (Figure 2). Now from the plant’s perspective, all of this packaging is absolutely critical for its survival and is designed to protect the plant embryo and its stored sources of energy and protein to ensure it will be able to grow and survive for the first few days following germination.

 

Figure 2: The location of starch granules (stained black) within the endosperm cells of barley grain surrounded by the protein matrix (stained green) and protected by the aleurone layer and seed coat.

 

So, the packaging is clever and essential from the plant’s perspective, however for the horse, all of this packaging is just a nuisance and prevents the horse from being able to digest and extract the energy from the grain. In fact, this packaging was actually specifically designed to allow a grain to pass through the gastrointestinal tract of an animal undamaged so it may germinate when it is excreted in the manure.

How does this packaging stop starch digestion?

The packaging can be likened to a security system at a casino which prevents the thieves (or in this case the enzymes) from stealing the cash (the starch). To digest the starch the enzymes in the horse’s small intestine must first breech the seed coat, then penetrate the aleurone layer. Following this they need to be able to make their way through the endosperm cell walls (these are the cells that contain the starch), then burrow through the sometimes impenetrable vault of the protein matrix before finally reaching the starch granule. Then, in a cruel twist of fate, if the enzyme reaches this far, it will find that the starch is bundled so tightly into a ball that the enzymes cannot digest it. So the horse is presented with a difficult hurdle—just how does it go about extracting the energy held in the starch of cereal grains?

 

Enter cooked grains…

It has been recognised for many years now that to effectively digest cereal grains, horses need some help. And that help comes in the form of ‘cooking’. Cooking grains using processes like extrusion, micronising and steam flaking breaks down the barriers the enzymes have to face in reaching and digesting cereal grain starch.

How cooking helps

When grains are cooked using a combination of heat, moisture, pressure and some form of physical process like rolling or grinding, the entire structure of the grain is disrupted. To start, the seed coat and aleurone layer are broken and the endosperm cell walls are opened up. In addition, the structure of the protein matrix is physically disrupted so it is no longer able to protect the starch granules. Cooking also turns the ordered and tightly packed structure of the starch granule into an open and vulnerable structure which can be easily attacked by enzymes in a process known as gelatinisation. Cooking simply gives the horse’s enzymes access to the grain starch so they can go about their work of cutting up the starch into single glucose molecules, which the horse then absorbs from the small intestine into the body, where it is used for energy.

What about cracked grains?

Simply cracking, crushing or grinding grains is the same process as chewing and aims only to change the physical structure of the grain, breaking the seed coat and reducing the grains particle size to give the enzymes better access to the starch within the centre of the grain. While the seed coat and aleurone layer barriers are removed, physical processing only causes minor damage to the endosperm cell walls and leaves a majority of the protein matrix and starch granule structure intact, meaning only small improvements to starch digestion will be made. Work conducted in horses showed that cracking corn only improved its digestibility in the small intestine of the horse by 1%. So while physical processing can get an enzyme through the front doors of the casino, gives them access to some of the cash floating around at the tables, and maybe even gets them into the strong room, it leaves the enzymes without a key, security code or set of explosives to get it into the vault. In short, they aren’t much better than whole grains.

Does soaking grains help?

Soaking grains simply makes them much easier to chew, so soaking will help the horse to break the seed coat and aleurone layer barriers. However soaking does nothing to disrupt the endosperm cell wall, protein matrix or starch granule structure, so, like cracking grains, soaking does not help to improve starch digestion.

What happens if cereal grains are fed without being cooked?

Starch from grains fed whole or cracked will remain largely undigested as it passes through the small intestine and will eventually be delivered to the hindgut. This is where the trouble begins. The bacteria in the hindgut do not face the same barriers as the enzymes in the small intestine, and they are able to reach and rapidly ferment the starch contained in uncooked grains. This rapid fermentation of starch causes excessive production of acids, which accumulate in the hindgut and lower the hindgut pH (the hindgut contents become acidic). Low pH in the horse’s hindgut causes a multitude of diseases and behavioural disturbances including laminitis, colic, endotoxaemia, systemic acidosis, reduced fibre fermentation, poorappetite, wood chewing and the eating of bedding as well as deficiencies in the B-group vitamins (including biotin) and vitamin K.

What about oats?

The general consensus is that oats can be fed unprocessed. As it is a larger grain, horses are capable of chewing the grain enough to break its seed coat, removing the need for physical processing. Studies have also found that oat starch is far easier to digest than corn or barley starch in an uncooked form. So oats can be fed whole and uncooked. However, whether oats can be fed unprocessed needs to be decided on a horse by horse basis. Observe your horse’s manure closely when you are feeding him oats. If you observe whole oat grains in his manure, whole oats is not a suitable feed for this horse. It is important to make sure the oats you are observing in the manure are whole and not just undigested hulls. Do this by taking them from the manure and squeezing them. If they are whole you will observe the white starch oozing from the centre. If you want to feed oats specifically, but your horse doesn’t digest them well, cracked, steam rolled and micronised oats can be purchased.

And the moral of the story…

Don’t feed cereal grains unless they have been cooked, with the exception of oats for some horses. If you feed whole, uncooked cereal grains, your horse will get little benefit from them and they have a good chance of causing disease and behavioural problems. Remember, the reason you feed cereal grains is to provide your horse with a source of energy. Most of this energy is held within the grain’s starch. If the horse can’t digest this starch, then you are better off not feeding the grain at all.

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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