11/07/2026
The basis to my mares feed. EMS safe ✅ soaked lupins, lupin fibre cubes plus & speedibeet all soaked & weighed with wet Rhodes chaff. Rhodes hay at liberty in hay bags hanging in different locations. Lives on a track system with 24hr access to her stable. She sleeps in her stable every night by choice. It's been a big learning curve about EMS, but I've learnt it's a condition not an unsoundness. All maintainable when managed correctly!
Lupins, Lupin Hulls and Beet Pulp:
GMO Claims, VFAs and the Evidence on Gastric Ulcers
I have written this article in response to the messages and texts I have received from horse owners who are worried that feeding beet pulp, lupins, or lupin hulls may cause ulcers in their horses.
You had better grab a drink and sit down, as this article is a long read! I don't think the Facebook algorithm will like it. Please, if you can, share and make a comment or whatever the cool social media savvy folk say. But it's something I felt strongly that I needed to comment on.
Horse owners' concern is understandable. Many owners are already doing their best to manage horses with gastric ulcers, EMS, PPID, insulin dysregulation, laminitis risk, poor condition, hindgut sensitivity or other digestive concerns.
When an online post claims that commonly used fibre feeds “cause ulcers” or are “all GMO”, unnecessary fear can spread very quickly.
However, the available evidence does not establish that beet pulp, Australian sweet lupins, or lupin hulls directly cause gastric ulcers.
The aim of this article is not to attack anyone personally. It is to explain what may have been misunderstood, what the research actually investigated and why these feeds should not be blamed for gastric ulcers without appropriate evidence.
1. Are Australian Lupins GMO?
The claim that Australian lupins used in horse feeds are GMOs is not supported by Australia’s current regulatory position.
The Office of the Gene Technology Regulator lists five genetically modified crops approved for cultivation in Australia: cotton, canola, Indian mustard, banana and safflower. Lupins are not included on that list (Office of the Gene Technology Regulator [OGTR], 2025).
Australian sweet lupins were developed through conventional plant breeding and selection. Breeding programs selected plants with lower seed alkaloid concentrations, improved yield and better adaptation to Australian growing conditions.
Australian lupin breeding has produced adapted, low-alkaloid varieties commonly known as “sweet lupins”. This is conventional plant breeding, not the commercial release of a genetically modified lupin crop (Grains Research and Development Corporation [GRDC], 2025).
Selective breeding and genetic modification are not the same process.
The accurate statement is:
Australian-grown commercial sweet lupins should not be described as GMOs. Lupins are not currently listed among the GM crops approved for commercial cultivation in Australia.
Product sourcing and traceability should still be checked when the country of origin or ingredients are uncertain.
2. Are Lupin Hulls GMO?
Lupin hulls are the fibrous outer seed coat separated from the lupin kernel during processing.
If the original lupin seed is not genetically modified, removing, grinding, micronising or pelleting its outer hull does not make it genetically modified.
Processing changes the physical form of an ingredient. Genetic modification involves altering the genetic material of an organism using biotechnology. These are not the same process.
Therefore:
Lupin hulls obtained from Australian sweet lupins should not be called GMO simply because they have been separated from the seed or processed into a horse feed.
3. Are All Beet-Pulp Products GMO?
No. It is not accurate to claim that all beet pulp is GMO.
Beet pulp is the fibrous material remaining after most of the sugar has been extracted from sugar beet. Its GMO status depends on the crop from which it originated, its source country and the manufacturer’s product declaration.
For example, British Horse Feeds currently describes Speedi-Beet™ as a non-GM product made from British beet pulp, with no added molasses, additives or preservatives.
The manufacturer has also stated that although Roundup Ready sugar beet has been licensed for sale in the European Union, it is not grown in the United Kingdom or processed at British Sugar plants (British Horse Feeds, 2018, n.d.).
These are product-specific manufacturer declarations. They should not automatically be applied to every beet-pulp product sold worldwide.
The accurate message is:
Some beet pulp may originate from GM sugar beet, depending on its source. However, it is incorrect to claim that all beet pulp is GMO. Horse owners should check the product specification, country of origin and manufacturer’s declaration.
4. Processed Does Not Mean Genetically Modified
Another source of confusion is the word “processed”.
A processed feed is not automatically genetically modified or unsafe.
Common feed-processing and preparation methods include:
soaking;
cracking;
rolling;
grinding;
micronising;
pelleting;
flaking;
extruding.
These methods alter the physical form of an ingredient and may improve chewing, hydration, nutrient availability and digestibility.
A processed or soaked lupin is still a lupin. It does not become a cereal grain, and it does not become genetically modified because it has been soaked, cracked, rolled, pelleted, micronised or extruded.
Why Whole Lupins Should Be Soaked
Whole lupins have a tough outer seed coat. The horse’s stomach acid should not be relied upon to mechanically break open an intact seed after it has been swallowed.
Whole lupins should therefore be soaked before feeding to soften the seed coat, improve chewing and allow better access to the protein, oil and fermentable carbohydrate within the kernel.
Alternatively, lupins may be fed in a suitable processed form, such as cracked, rolled, micronised, pelleted or extruded.
Only clean, sweet, low-alkaloid, stockfeed-grade lupins should be used. Soaking does not make bitter, mouldy, contaminated or otherwise unsuitable lupins safe to feed.
5. What Are These Feeds Nutritionally?
Lupins, lupin hulls and beet pulp should not automatically be grouped with high-starch cereal grains. However, they are also not nutritionally identical to one another.
Lupins are legume seeds rather than cereal grains.
Their carbohydrate composition is characterised by negligible or very low starch and higher concentrations of soluble and insoluble non-starch polysaccharides. They also provide protein, oil and fermentable carbohydrate (van Barneveld, 1999).
This makes lupins nutritionally different from cereal grains, e.g., barley, oats, wheat and maize.
Lupins are not simply a fibre supplement. However, their protein, energy, amino-acid profile, fat content and total inclusion rate must be considered within the complete diet.
Lupin hulls: Are the fibrous outer coat of the seed.
They contain considerably more structural fibre and less protein and energy than the lupin kernel. They may be used as part of a high-fibre feed, but their nutritional value depends on processing, quality, particle size and the formulation of the final product.
Beet pulp: Unmolassed beet pulp is a high-fibre, low-starch ingredient remaining after sugar extraction.
Although it comes from sugar beets, beet pulp is not the same as feeding sugar. Products containing added molasses will differ from unmolassed beet pulp and should be assessed using their individual sugar and starch analysis.
Ford and colleagues examined the effect of partially replacing hay with sugar beet pulp in healthy adult horses.
The study found changes in several bacterial groups and predicted microbial pathways, including pathways associated with butyrate production (Ford et al., 2023).
However, this was a small, short-term study of the faecal microbiome. It did not investigate gastric ulcers and should not be interpreted as proving that beet pulp prevents ulcers or other gastrointestinal diseases.
The authors concluded that larger studies were required to assess whether beet pulp has a protective effect against gastrointestinal conditions.
The nutritional value and suitability of beet pulp, lupins and lupin hulls should therefore be assessed according to:
The individual product analysis;
whether molasses or other ingredients have been added;
the horse’s body weight and workload;
metabolic and health status;
dental function;
total protein and energy requirements;
the remainder of the forage and feed ration;
The amount fed per meal and per day.
6. What Are VFAs?
When microbes, aka bugs & bacteria in the hindgut, ferment fibre, they produce short-chain fatty acids, which are also commonly called volatile fatty acids or VFAs.
The principal VFAs include:
acetate;
propionate;
butyrate.
Horses are hindgut fermenters. Microorganisms in the caecum and large colon ferment fibre that cannot be digested by the horse’s own enzymes.
The VFAs produced are absorbed through the hindgut wall and contribute energy to the horse.
Acetate is commonly the major VFA produced during fibre fermentation and can be used by muscles and other tissues for energy.
Propionate can be transported to the liver and used as a substrate for glucose production.
Butyrate is an important energy source for the cells lining the colon and contributes to normal intestinal barrier function.
The production of VFAs during hindgut fibre fermentation is therefore a normal and essential part of equine digestion.
A feed does not produce only one individual acid. Different fibre sources produce mixtures of VFAs, with the proportions influenced by:
fibre type;
particle size;
processing;
total diet composition;
microbial population;
rate of passage;
amount consumed;
The horse’s adaptation to the feed.
7. Why Have VFAs Been Linked With Gastric Ulcers?
This is where the scientific information may have been misunderstood.
VFAs are normal products of hindgut fibre fermentation. However, organic acids may also damage the less-protected squamous lining of the stomach under sufficiently acidic gastric conditions.
The location, concentration, pH and physiological circumstances are critical.
Nadeau and colleagues investigated the effects of hydrochloric acid and the VFAs acetic, butyric and propionic acid on the non-glandular or squamous portion of the equine stomach.
The study found VFAs could impair the barrier function of the squamous gastric mucosa when the gastric pH was 4 or below. Hydrochloric acid alone, and hydrochloric acid combined with VFAs under acidic conditions, may therefore contribute to squamous gastric injury (Nadeau et al., 2003).
That is genuine and important ulcer research.
However, the study:
Exposed equine gastric tissue to prepared acid solutions;
Examined the effect of acid and pH on the squamous mucosa;
Did not feed horses beet pulp;
Did not feed horses lupins;
Did not feed horses lupin hulls;
Did not demonstrate that any of these ingredients caused gastric ulcers.
The study identified a potential mechanism through which organic acids may damage the squamous stomach lining under acidic gastric conditions.
It did not show that the normal production of VFAs through fibre fermentation in the hindgut causes gastric ulcers.
It is therefore incorrect to take the finding that:
“VFAs may contribute to squamous gastric injury at a low stomach pH”
and change it into their claim:
“Beet pulp, lupins or lupin hulls cause ulcers.”
Those are not equivalent conclusions.
8. What Actually Contributes to Gastric Ulcers?
Equine gastric ulcer syndrome is multifactorial and includes two separate disease categories.
Equine squamous gastric disease
Equine squamous gastric disease, or ESGD, affects the upper squamous or non-glandular region of the stomach.
It is associated with exposure of the less-protected squamous lining to acidic gastric contents.
Recognised risk factors and management concerns include some of the following:
inadequate forage intake;
long periods without eating;
intermittent feed deprivation;
high-starch concentrate meals;
low meal frequency;
intense or frequent exercise;
acidic gastric contents splashing onto the squamous mucosa during exercise;
prolonged stabling;
travel;
racing and intensive training;
management stress;
Reduced appetite or illness.
Equine glandular gastric disease
Equine glandular gastric disease, or EGGD, affects the lower glandular region of the stomach.
The glandular mucosa has protective mechanisms that the squamous mucosa does not have. EGGD is therefore considered a different disease process from ESGD, and its causes are less completely understood.
Exercise frequency, management, stress and impairment of normal mucosal defence may be involved.
Excessive or inappropriate NSAID use can also cause gastric mucosal injury, although not every case of EGGD is caused by NSAIDs.
The European College of Equine Internal Medicine consensus statement clearly separates ESGD and EGGD because they do not have identical causes, risk factors or treatment considerations (Sykes et al., 2015).
The later review by Vokes, Lovett and Sykes also emphasises that EGUS is an umbrella term covering separate gastric diseases rather than one condition with one single dietary cause (Vokes et al., 2023).
Murray and Eichorn demonstrated that severe squamous gastric ulceration can develop rapidly when horses undergo repeated periods of feed deprivation. This supports the importance of avoiding prolonged periods without forage in ulcer-prone horses (Murray & Eichorn, 1996).
Australian work by Lester, Robertson and Secombe also described gastric ulceration in Thoroughbred racehorses as a multifactorial disease involving physiological, psychological and management-related factors (Lester et al., 2007).
None of this research supports blaming one low-starch fibre ingredient as the single cause of gastric ulcers.
9. Why Forage and Saliva Matter
Horses secrete gastric acid continuously, but they produce significant quantities of saliva mainly while chewing.
Saliva contains bicarbonate and helps buffer gastric acid.
Long-stem forage encourages more chewing than a small concentrate meal and is therefore an important part of nutritional management for ulcer-prone horses.
The 2015 ECEIM consensus statement recommended unlimited or frequent forage access and at least 1.5 kg of forage dry matter per 100 kg of body weight each day.
For a 500 kg horse, this minimum would provide:
7.5 kg of forage dry matter per day.
If the hay contains approximately 90% dry matter, this is equivalent to roughly:
8.3 kg of hay as fed per day.
Many horses will require closer to 2% of body weight in forage dry matter to support body condition, digestive health and normal feeding behaviour.
For a 500 kg horse, 2% of body weight would provide:
10 kg of forage dry matter; or
Approximately 11.1 kg of hay as fed when the hay is 90% dry matter.
The correct amount must still be adjusted for:
body condition;
workload;
metabolic status;
forage energy and NSC;
dental function;
pasture intake;
wastage;
age and health;
Whether weight gain, maintenance or weight loss is required.
Ulcer-prone horses should ideally not be left for long periods (under 4 hrs) without suitable forage.
Smaller, more frequent feeds and consistent access to appropriate forage may help maintain chewing, saliva production and a more stable gastric environment.
Grass hay, meadow hay, Rhodes hay, pasture and controlled amounts of lucerne may all have a place depending on the individual horse and the forage analysis.
The correct forage choice depends on more than ulcers alone. Sugar and starch, protein, calcium, phosphorus, magnesium, oxalates, hygienic quality and the horse’s ability to chew must also be considered.
10. Does Beet Pulp, Lupins or Lupin Hulls Cause Gastric Ulcers?
Based on the currently available evidence, it is not justified to claim that beet pulp, Australian sweet lupins or lupin hulls directly cause gastric ulcers.
The available research does not demonstrate that feeding these ingredients causes either ESGD or EGGD.
The confusion appears to arise from taking research about the effects of organic acids on the squamous stomach lining at a low gastric pH and applying it directly to named fibre ingredients that were not tested in that research.
These are different questions.
Beet-pulp and lupin-hull fibre are fermented predominantly by microorganisms in the hindgut. The resulting VFAs contribute to the horse’s normal energy supply.
That normal hindgut fermentation process should not be confused with exposing the squamous stomach lining to organic acids in an acidic gastric environment.
This does not mean that every product containing beet pulp, lupins or lupin hulls is automatically suitable for every horse.
Nor does it mean that they should be fed without limits or without balancing the complete diet.
It means these ingredients should be judged accurately rather than blamed for gastric ulcers without direct evidence.
Correct Use Still Matters
Saying that beet pulp, lupins and lupin hulls do not directly cause gastric ulcers does not mean they should be fed carelessly, in unlimited amounts or without considering the individual horse.
Like any feed ingredients, they need to be used correctly.
Beet pulp, lupins and lupin hulls should be:
introduced gradually over 14–21 days;
fed at suitable rates for the horse’s body weight, workload and health status;
matched to the individual horse’s needs;
included within a balanced, forage-first diet;
checked for quality, freshness and suitability;
prepared correctly according to the ingredient or manufactured product;
Balanced with the required minerals, trace elements, amino acids, salt and vitamins.
Poor-quality, mouldy, dusty, contaminated, weather-damaged or incorrectly prepared feeds are never appropriate for horses.
Sweet lupins used for stockfeed are selected for low alkaloid concentrations, but only clean, sweet, low-alkaloid, stockfeed-grade lupins should be fed.
Bitter, mouldy, contaminated, weather-damaged or discoloured lupins are not suitable for horses.
Whole lupins should be soaked before feeding, or supplied in a suitable processed form, so the horse can chew and digest them more effectively.
Manufactured lupin and beet-pulp products should always be prepared according to their individual label directions.
The correct message is not:
“Feed as much as you like.”
The correct message is:
Use the right feed, in the right form, at the right amount, introduced gradually, with enough forage and the correct mineral and nutritional balance.
Broad claims that beet pulp, lupins and lupin hulls are “all GMO” or directly “cause ulcers” are not supported by the available evidence.
Australian commercial lupins are not listed as a GMO crop approved for commercial cultivation in Australia.
Lupin hulls do not become genetically modified when they are separated or processed.
The GMO status of beet pulp depends on its original source, and products such as Speedi-Beet™ are specifically declared non-GM by their manufacturer.
Most importantly, research showing that organic acids can damage squamous gastric tissue at a low pH does not prove that feeding beet pulp, lupins, or lupin hulls causes gastric ulcers.
Suspected gastric ulcers should be discussed with a veterinarian. Gastroscopy is required to confirm gastric disease and determine whether the horse has ESGD, EGGD or both.
Image created using AI for illustration. Equine Nutrition information written, researched and reviewed by Feed Your Steed.
References
British Horse Feeds. (2018, June 20). Speedi-Beet: Does it matter where the beet comes from?
British Horse Feeds. (n.d.). Speedi-Beet.
Ford, T., McAdams, Z. L., Townsend, K. S., Martin, L. M., Johnson, P. J., & Ericsson, A. C. (2023). Effect of sugar beet pulp on the composition and predicted function of equine faecal microbiota. Biology, 12(9), 1254. doi: 10.3390/biology12091254
Grains Research and Development Corporation. (2025). Lupin crop improvement plan.
Lester, G. D., Robertson, I. D., & Secombe, C. (2007). Risk factors for gastric ulceration in Thoroughbred racehorses. In Proceedings of the 53rd Annual Convention of the American Association of Equine Practitioners (Vol. 53, p. 529).
Murray, M. J., & Eichorn, E. S. (1996). Effects of intermittent feed deprivation, intermittent feed deprivation with ranitidine administration, and stall confinement with ad libitum access to hay on gastric ulceration in horses. American Journal of Veterinary Research, 57(11), 1599–1603.
Nadeau, J. A., Andrews, F. M., Patton, C. S., Argenzio, R. A., Mathew, A. G., & Saxton, A. M. (2003). Effects of hydrochloric, acetic, butyric, and propionic acids on the pathogenesis of ulcers in the nonglandular portion of the stomach of horses. American Journal of Veterinary Research, 64(4), 404–412. doi: 10.2460/ajvr.2003.64.404
Office of the Gene Technology Regulator. (2025, December). Snapshot of genetically modified crops in Australia. Australian Government.
Sykes, B. W., Hewetson, M., Hepburn, R. J., Luthersson, N., & Tamzali, Y. (2015). European College of Equine Internal Medicine consensus statement—Equine gastric ulcer syndrome in adult horses. Journal of Veterinary Internal Medicine, 29(5), 1288–1299. doi: 10.1111/jvim.13578
van Barneveld, R. J. (1999). Understanding the nutritional chemistry of lupin (Lupinus spp.) seed to improve livestock production efficiency. Nutrition Research Reviews, 12(2), 203–230. doi: 10.1079/095442299108728938
Vokes, J., Lovett, A., & Sykes, B. W. (2023). Equine gastric ulcer syndrome: An update on current knowledge. Animals, 13(7), 1261. doi: 10.3390/ani13071261
