There is ongoing debate within the equine community regarding whether water-soluble carbohydrates (WSC) or ethanol soluble carbohydrates (ESC) hold greater significance when evaluating the safety of forages and feeds for horses prone to laminitis. When discussing or calculating non-structural carbohydrates (NSC) in a diet, FeedXL opts for the inclusion of (WSC) along with starch to determine NSC. Here’s the rationale behind this choice.
WSC encompasses simple sugars as well as fructans, whereas ESC solely represents the measurement of simple sugars.
Previously, it was believed that hindgut acidosis, resulting from fructan fermentation, was the primary cause of pasture-associated laminitis, similar to the effect of starch in grain overload. However, through research, it has been discovered that sustained high insulin levels are responsible for pasture-associated laminitis.
Nevertheless, can we conclude that the absorption of simple sugars, as measured by ESC, is solely responsible for the insulin response? While simple sugars directly impact insulin levels, there are two potential ways in which fructans could also influence the insulin response.
Firstly, fructans are carbohydrates with varying chain lengths, consisting of fructose sugar molecules joined together with a glucose molecule at the end. Although most of these fructose bonds are not broken down by a horse’s enzymes, it is believed that some fructans, particularly the shorter chain ones, may undergo acid hydrolysis in the stomach or microbial fermentation in the small intestine. This process produces simple sugars, namely fructose and glucose, which can be absorbed by the horse and contribute to an insulin response.
Secondly, undigested fructans pass into the hindgut, where they undergo rapid fermentation. This fermentation leads to a significant increase in bacteria that preferentially ferment fructans, resulting in the production of lactic acid. The change in hindgut environment, becoming more acidic, causes a shift in microbial populations and reduces the diversity of microbes, including the desirable fiber-fermenting ones. While research in this area is still in its early stages, it is plausible that hindgut microbes can influence the insulin response, similar to humans.
Using ESC to calculate NSC may underestimate NSC and ignore fructans, potentially putting your horse at risk.
Hence, FeedXL recommends and uses the more conservative approach by considering WSC when examining the NSC component of forages (NSC = WSC + Starch). This approach is more conservative because WSC values are consistently higher than ESC values and still aligns with the principle of minimizing insulin spikes by limiting dietary simple sugars. Additionally, by maintaining low fructan levels in the diet, the negative impact on hindgut microbial populations caused by fructan fermentation is minimized, indirectly influencing the insulin response.
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With pasture sometimes forming the majority, if not all, of our horse’s diets, it’s important to enter pasture quality as accurately as you can in FeedXL.
Pasture quality corresponds with the amount of digestible energy, crude protein, macro minerals and vitamins your pasture is providing. Therefore, pasture quality determines what else you may (or may not) need to supply in your horse’s diet to meet their nutritional requirements.
We like to keep it simple when it comes to deciding pasture quality – by looking at colour and presence or absence of seed heads (basically stage of maturity). When pasture is overgrazed (less than 1 inch in height), it’s unlikely you’ll see any seed heads, therefore colour is your major guide.
So, next time you’re entering your pasture use the definitions and images below to help you determine quality.
Pasture Quality
Overgrazed
Excellent
Green
Actively growing
Very leafy
Virtually no flowers or seed heads visible
Good
Green
May or may not be actively growing
Flowers and/or seed heads are present
Plants are beginning to mature and become stemmy
Average
Green to yellow or brown
Most plants are stemmy and/or have visible flowers and/or seed heads present
Poor
Completely brown
Plants are stemmy and/or have visible seed heads present
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Forage is theSingle. Most. Important component of your horse’s diet… for a whole bunch of reasons!
It is your horse’s biggest source of calories, protein and some vitamins and minerals.
It keeps your horse’s gut full and less prone to colic.
It encourages saliva production during chewing and keeps the stomach full to dramatically reduce the risk of gastric ulcers.
It feeds your horse’s good bacteria which then produce vitamins and hormones that keep your horse calm, healthy and happy plus they keep the immune system functioning properly!
It holds onto water in the gut and provides a rich source of electrolytes to keep your horse properly hydrated.
AND – perhaps one of the most important functions of forage – it keeps your horse chewing, head down and content!
So it’s REALLY important to have ENOUGH forage in your horse’s diet and it’s also a wonderful idea to have a VARIETY of forage in the diet.
In FeedXL, you will be warned if your horse’s diet does not contain enough forage!
Here’s what that will look like:
So be sure to meet the minimum daily forage requirement!
Then my very best advice is, don’t stop there!
Don’t JUST meet the minimum forage requirement!
The more forage you can get into your horse’s diet, the better!
So here is a tip… in FeedXL, enter all of your horse’s forages, pasture, hay, chaff, forage cubes or pellets, haylage… anything that is considered forage!
Then go to the results and look at your horse’s ‘Total Daily Feed Intake’ amounts. Is it at 100%? Or is it less than 100%?
If it is at 100% or above (extra stars for above!), look at your horse’s nutrient graph, looking specifically at the Digestible energy level. Is it between 90 and 100%?
If it is, and ALL you have in the diet is FORAGE this means forage can be used to meet 100% of your horse’s daily Digestible Energy (calorie) requirements and you are unlikely to need a feed!
(You will however still need to add a supplement to top up mineral and some vitamin levels and may need to add some high quality protein – more on this here.)
A High forage diet is best for gut and overall health
This high forage diet, especially if it contains a variety of forage, is the closest diet you can get to a horse’s natural diet and will be the best in terms of gut and overall health for them!
If your horse’s energy is too low (less than 90% OR your horse is currently losing weight on an all forage diet) then you will need to add some higher energy ingredients to the diet. But keep in mind that you still want to keep as much forage in the diet as you possibly can!
Some suggestions for higher energy ingredients include sugarbeet pulp, copra meal, lupins, lupin hulls, higher energy forages like alfalfa/lucerne, oils and if they are safe for your horse, oats or other cereals (like corn/maize or barley) AS LONG AS THE GRAINS ARE COOKED!
The trick is to add as little of these ingredients as possible in FeedXL to meet that digestible energy requirement so you keep as much of your forage in the diet as possible!
So keep adding small amounts of your chosen high energy ingredients and keep checking your results to see when you have added enough energy.
And here is a little heads up to save you getting confused…
If your horse is on free choice pasture or hay you will notice that as you add a new ingredient your horse’s pasture or free choice hay intake will go down as you ad other ingredients.
For example if your horse’s free choice forage intake is 10 kg/day…
And then you add 0.5 kg/day of oats, free choice forage will go down to 9.5 kg/day…
Why?
Because your horse only has so much room in its gut for feed each day. So as you increase in this example, oats in the diet, your free choice forage intake is reduced proportionally.
Really hope that all helps! If you remember lots of forage PLUS a variety of forage your horse is going to be so far ahead in term of health and nutrition!
If you have read this far, kudos to you!
Big thanks for being here and remember if you have questions, just ask!
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Oaten hay is commonly fed to horses. Recent research by Jackson et al (2018)1 suggests however that we should be cautious with oaten hay as it may be negatively affecting our horses’ dental health!
The Study
Dr Kirsten Jackson (https://dentalvet.com.au) and her co-researchers found in a study of 500 Western Australian horses, that oaten hay was significantly associated with an increased incidence of dental caries (tooth decay).
Image credit: Dr Kirsten Jackson (https://dentalvet.com.au)
How does Oaten Hay do this?
Dental caries form when bacteria in your horse’s mouth metabolise sugars in the hay/ feed and produce the by-product of acid. This acid demineralises the teeth causing decay which in horses generally means the outer layer (cementum) is stripped from the teeth.
Because oaten hay can be so high in water soluble carbohydrates (WSC; also loosely called ‘sugars’) the oaten hay feeds the oral bacteria, a lot… and then they produce a lot of acid… and the acid demineralizes (eats away) the hard part of the teeth.
It is thought that the near constant supply of sugars to the bacteria in the mouth when a horse has constant access to oaten hay, and therefore the prolonged periods of exposure of the teeth to the acids produced by the bacteria is what puts horses on oaten hay at higher risk of disease.
What about other types of hay or pasture?
Dr Jackson reports that in the same study it was found that a meadow hay based diet was protective. And horses with access to good quality grazing all year round were less likely to have peripheral caries than horses that had no access to grazing.
Other similarly high WSC hays like ryegrass hay and other cereal hays like barley and wheaten hay will potentially put horses at the same risk as oaten hay.
What can be done if my horse has dental caries?
The good news is that because a horse’s teeth are constantly erupting, and the acid produced when high WSC hay is fed only affects the part of the tooth that is physically exposed to it (so the tooth below the gumline remains unaffected), dental caries can be treated.
Jackson et al 2021 showed that when oaten hay was swapped for a lower WSC meadow hay, it allowed teeth to start to recover.
The authors note that full recovery generally takes around 2 years.
Image credit: Dr Kirsten Jackson (https://dentalvet.com.au)
Should oaten and other high WSC hays be completely avoided?
Not necessarily. It seems in this study that it was horses with free access to oaten hay that were most affected.
If you are in an area where other type of hay is difficult to source and using SOME oaten hay helps to get you through, then using some, mixed with a variety of other hays and/or access to pasture is potentially OK.
Also not all horses on oaten hay were affected so there is some individual variability in susceptibility to the caries so some horses can be ok on oaten but if your horse has caries it is best to avoid it. If your horse is on oaten hay and this can’t be avoided it is probably a good idea you have regular veterinary dental examinations conducted every 6 months.
If you are spoilt for choice with hay and can avoid oaten hay, you are probably best to avoid it completely… especially if you have a thoroughbred as they were also shown to be at higher risk!
References
1. Jackson, K., E. Kelty, and M. Tennant, Equine peripheral dental caries: An epidemiological survey assessing prevalence and possible risk factors in Western Australian horses. Equine Vet J 2018. 50(1):79-84.
2. Jackson, K., E. Kelty, and M. Tennant, Retrospective case review investigating the effect of replacing oaten hay with a non-cereal hay on equine peripheral caries in 42 cases. Equine Vet J 2021. 53(6):1105-1111.
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Straw is gaining favouritism among nutritionists and horse owners as part of diets for easy keepers. It allows energy intake of the diet to be reduced without drastic restriction in a horse’s daily feed intake.
This strategy is thought to improve the welfare of easy keepers and reduce the risk of colic and gastric ulceration, all common issues seen with feed restriction.
A recent study that substituted 50% of the grass haylage component of the diet with straw, further supports the use of straw in easy keeper diets.
The main findings in the study (Jansson et al 2021) were that the 50% straw diet had:
No effect on squamous or glandular gastric ulcers scores
Longer feed intake times and lower energy intakes
Lower Insulin concentrations (a positive for those prone to laminitis)
A trend for higher serotonin levels (a key hormone that stabilises mood; inhibits aggression, fear and stress; supports intestinal motility; plays a role in fat tissue metabolism)
Gut sounds that reflected normal motility patterns and no changes in manure moisture content– indicating no major adverse effects on gut function.
Why Should You Consider Including Straw?
It is now widely accepted that horses should be eating a minimum of 1.5% of their bodyweight in forage per day (dry matter basis). This supports natural behaviour and minimises the risk of health complications such as gastric ulcers and colic.
However, for some easy keepers, this amount of forage alone can exceed energy requirements. Therefore, replacing some higher energy forage in the diet with low energy straw can allow owners of easy keepers to reduce the energy content of the diet without restricting intake below 1.5% of bodyweight.
More bulk. Less energy! Happier horses!!
Isn’t There a Risk of Gastric Ulcers on Straw Diets?
A previous study published in 2009 reported the incidence of gastric ulcers (both glandular and squamous) was increased in horses fed straw as their only roughage source. The authors (many of which are the same authors on the above-mentioned paper) suggested that mechanical damage, changes in the gastric contents, specifically the fibre ‘mat’ that forms in the stomach, and reduced buffering capacity due to low calcium and protein content of straw could have been the cause.
However, in the present study the severity and incidence of gastric ulcers decreased over the study period (2 x 21 days). This suggests that including up to 50% of the forage in diets as straw does not increase the risk of gastric ulceration.
And in fact the slower intake of straw is likely to be a good strategy for ensuring horses don’t go longer than 4 hours without feed. Which should then act to reduce the risk of ulcers.
Decreased Feed Intake, No Time Without Forage
The 50% straw diet offered in 2021 study contained the same amount of energy as the haylage only diet. This meant that horses on the straw diet were receiving more forage (based on dry matter) than the haylage diet.
However, the researchers found that the horses on the straw diet actually had leftovers which resulted in them consuming less energy each day (10.7MJ per 100kg bodyweight) compared with the haylage group (12.4MJ per 100kg bodyweight).
This suggests that because horses are ‘fuller’ or more satisfied on the straw diet, they are likely to eat less forage which may decrease energy intake without the need for intake restriction.
Longer Periods Spent Eating
Another benefit of the 50% straw diet was that horses spent more time eating each day compared with the haylage only diet. The authors calculated that the horses on the straw diet spent 11.2 hours per 24 hours eating whereas the control diet horses spent 6.2 hour per 24 hours eating – an 80% difference!
The most likely explanation is differences in palatability or some physiological response as the NDF (measure of the cell wall components such as hemicellulose, cellulose and lignin) content of the two diets was very similar – NDF content is correlated to intake.
The authors noted that interestingly, the horses on the straw diet spent more time pausing their feed intake whereas the haylage diet was consumed almost at all at once.
Lower Insulin Response
Many easy keepers are at increased risk of laminitis. It is therefore in our best interest to feed a low sugar and starch diet which limits glucose and insulin responses.
In the present study, the insulin response was lower on the 50% straw diet than the haylage only diet. The total water-soluble carbohydrate (WSC) intake was significantly lower for the straw diet (60g vs. 75g per 100kg bodyweight) so this was not unexpected but does highlight another possible advantage of including straw in diets.
Be mindful that this cannot necessarily be generalised for all straw and analysis is recommended to determine the actual starch and WSC content of any straw you might consider using.
Also interesting to note that the grass forages used in this study were by no means high in WSC, being 7.7% and 4.9%, as compared with the straw being 0.8%.
Higher Serotonin Levels in Horses on the 50% Straw Diet
This is super interesting and the authors offered the explanation that chewing more and being more satisfied from a hunger perspective is potentially increasing serotonin levels and may be the reason why horses are eating less and taking more pauses between eating when offered the 50% straw diet.
It is well known in humans that spending longer chewing meals reduces hunger levels, with chewing stimulating serotonin.
Does Feeding Straw Increase the Risk of Impaction Colic?
The present study showed no difference in gut sounds between the haylage only diet and the diet with 50% inclusion of straw over the 21-day study periods. Nor did the moisture content of the manure vary between the two groups.
A lack of faecal moisture (or in other words, the presence of dry manure) may indicate increased risk of impaction colic. The authors noted that certain individuals and even some breeds are more prone to impactions and owners should be cautious.
All changes in forages should be made gradually over several weeks to minimise the risk of colic providing a chance for fibre digesting bacteria to adapt.
No More HANGRY Horses?!
Using straw in diets can add another string to our bow for managing the weight and seemingly insatiable appetite of easy keepers.
The results of this study suggest that inclusion of up to 50% of the forage ration as straw does not cause gastric ulcers and may in fact improve the welfare of easy keepers by reducing energy intake on ad lib hay and prolonging the time they spend eating.
Straw in effect lets us feed more bulk, while providing less energy. And keeps our horses fuller, happier, chewing for longer and less stressed!
Jansson, A., Harris, P., Davey, S.L., Luthersson, N., Ragnarsson, S.and Ringmark, S. Straw as an Alternative to Grass Forage in Horses—Effects on Post-Prandial Metabolic Profile, Energy Intake, Behaviour and Gastric Ulceration. Animals, 2021, Issue 11, Volume 8, Pages 2197-2211.
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I was honoured to have been part of the team who put together the Veterinary Clinics | Equine Practice book of clinical review articles on Equine Nutrition.
Together with Dr Brian Nielsen (Professor, Michigan State University) and Dr Carrie Finno (Associate Professor, UC Davis) we wrote the chapter ‘Nutritional and Non-nutritional Aspects of Forage’.
Hopefully it will make a great resource for equine veterinarians around the world!
The biggest take-home message…
Forage alone is unlikely to meet all nutrient requirements and some form of supplementation, be it in the form of supplements, balancers or feeds, will almost always be necessary to create a balanced diet!
If anyone would like a copy we would be happy to email it to you.
Richards N, Nielsen BD, Finno CJ. Nutritional and Non-nutritional Aspects of Forage. Vet Clin North Am Equine Pract. 2021 Apr;37(1):43-61. doi: 10.1016/j.cveq.2020.12.002. PMID: 33820609.
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Weight loss in easy keepers can seem like an impossible task and is often the cause of frustration for owners. Despite a strict hay only diet, many easy keepers can still maintain their body condition. Owners are also faced with the dilemma of not restricting intake too much (to avoid colic) while trying not to add too much energy to the diet. A study published recently investigated the effectiveness of adding straw to ponies diets to assist with weight loss. The outcomes provide some hope of weight loss for those with easy keepers.
Does feeding horses straw help with weight loss?
This study looked at 40 native-type ponies at pasture in the UK over winter. The ponies were split into two groups; supplementary fed hay alone or a 50:50 ratio of hay and barley straw. The ponies were weighed regularly over a 4 month period. Over this period, all ponies in the straw fed group lost an average of 27kg. Only 3 of 15 ponies in the hay group lost weight, and overall the group gained weight (average +6kg).
Why add straw to your horse’s ration?
Straw is lower in energy as compared with most grass hays, therefore substituting up to 50% of grass hay in the ration with straw, creates a less energy dense ration whilst maintaining adequate forage intake. This means that intake does not need to be severely restricted to achieve weight loss. In addition, the time horses spend eating per day is extended, which keeps them satisfied and at less risk of gastric ulcers due to prolonged periods without food.
Considering the risk of colic when feeding straw
The addition of straw into diet can be problematic due to the risk of colic. However, in this study there were no reports of colic. Care needs to be taken when choosing the right type of straw, and introduction to the diet should be done gradually over 14-21 days until a 50:50 ratio is achieved with hay to straw.
What type of straw is best for horse feed?
Oaten or barley straw is generally softer (less indigestible fibre) than wheaten straw and is therefore more commonly used for feed. If you have a feed analysis performed, look for an NDF of less than 65. You can also scrunch the straw in your hand to check the coarseness (technical I know!) – you’re feeling that the straw scrunches easily (stems are soft) and the sharp ends don’t prick your palm ie. we want to avoid bedding type straw.
While most straw is low in sugar and starch, a feed analysis to confirm this is a good idea. If a feed analysis is not practical for you, visually inspect the straw to ensure it doesn’t contain intact heads of cereal grains which may make the straw high in starch. Straw will be lower in protein than grass or cereal hays. Therefore, attention should be paid to supplying a good quality protein source within the diet as well as meeting mineral and vitamin requirements.
The difference between straw and hay
Straw vs. hay – for cereal crops, hay is the name given to a crop that is cut for hay when the grain is still maturing. Straw is a by-product which is cut after the plant has matured and the grain has been harvested from the plant.
Reference
Dosi, MCM., Kirton, R., Hallsworth, S., Keen, JA., Morgan, RA. (2020) Inducing weight loss in native ponies: is straw a viable alternative to hay? Veterinary Record Published Online First: 03 May 2020. doi: 10.1136/vr.105793
Meet The Author: Samantha Potter, MSc
In 2009, Sam completed a Bachelor of Equine Studies and it was during this time she developed an interest in equine nutrition. Pursuing this passion, Sam went on to complete her Honours followed by her Masters degree in equine nutrition at The University of Melbourne. Since 2015, Sam has worked as an independent nutritionist and enjoys supporting horse owners manage their horse’s nutrition in her role with FeedXL. To learn more about Sam and to ‘meet’ the rest of the FeedXL team, check out our About Us page here.
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Question: Can you touch base about grass and legume type hays, what each grass/legume benefits the horse’s overall health. Is a certain mixture better (or preferred) for certain horses; pasture pet, light work, moderate-heavy work, hard keeper, easy keeper, etc.
Example: benefits of having mixtures – pros to having certain types within the mix such as Birdsfoot Tree foil, orchard grass, climax timothy, Kentucky blue grass, spring green felstulolium, brome.
Watch the video below with FeedXL founder Dr Nerida Richards and SmartPak’s Dr Lydia Gray for the answer!
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
Question: When feeding a lot of alfalfa, what is the best way to keep a horse’s Calcium to Phosphorus ratio where it should be?
Watch the video below with FeedXL founder Dr Nerida Richards and SmartPak’s Dr Lydia Gray for the answer!
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
