How to Feed a Horse to Reduce Colic and Gastric Ulcer Risk

By Dr Duncan Houston

A horse can eat the same amount of feed each day and still have a very different risk of digestive disease depending on how that feed is delivered.

Long periods without forage, oversized concentrate meals, abrupt hay changes, reduced water intake and sudden pasture access can all increase gastrointestinal risk. At the same time, no feeding routine can prevent every gastric ulcer or every case of colic.

The goal is not to recreate a perfectly wild lifestyle. It is to build a practical routine that respects how the equine stomach and hindgut function while still meeting the horse’s weight, workload and medical needs.

Quick Answer

Keep forage at the centre of the diet, avoid routinely leaving horses without forage for more than approximately six hours, and introduce all hay, pasture and concentrate changes gradually over 10 to 14 days.

Grain-based concentrate should remain below 0.5% of body weight per meal. For a 500-kilogram horse, that is an upper limit of approximately 2.5 kilograms per meal, not a target. Ulcer-prone horses may require substantially lower starch intakes.

Maintain continuous access to clean water, feed forage before starch-rich concentrate, and call a veterinarian promptly if the horse develops abdominal pain, marked appetite loss, reduced manure, choke signs, diarrhoea or foot soreness.

Can Good Feeding Prevent All Colic and Gastric Ulcers?

No.

Feeding management can reduce several important and modifiable risks, but colic is a broad clinical sign rather than one disease. It may be caused by impaction, gas, intestinal displacement, strangulation, enteroliths, parasites, colitis, sand, lipomas, hernias and many other problems.

Gastric ulcer disease is also not controlled by feeding alone. Exercise, travel, stress, pain, illness, medications and individual susceptibility may all contribute.

The realistic goal is therefore to reduce avoidable risk, recognise early abnormalities and stop a minor management problem from becoming a gastrointestinal emergency. Systematic reviews identify concentrate intake, recent feed changes, housing changes and reduced pasture exposure as meaningful colic risks, but they do not support the claim that nearly every case of colic is caused by feeding. (PMC)

Why Does Feeding Routine Matter So Much?

Horses evolved to consume fibrous feed in repeated small amounts while moving.

A 2025 meta-analysis found that free-ranging horses spent approximately 56% of their daily time feeding, compared with 38% in stabled horses. Concentrated meals can provide calories within minutes, but they do not reproduce the chewing time, saliva production, gut fill or movement associated with forage consumption. (PubMed)

The equine digestive system also has several practical limitations:

• The stomach is relatively small.

• Gastric acid is produced even between meals.

• Saliva is produced mainly while chewing.

• Starch is primarily digested in the small intestine.

• Fibre is fermented by microbes in the caecum and colon.

• Abrupt feed changes can alter hindgut fermentation.

When large quantities of starch escape digestion in the small intestine, they enter the hindgut and are rapidly fermented. This can lower pH, disrupt fibre-digesting microbes and contribute to digestive upset, colic and laminitis. (OUP Academic)

Gastric Ulcers and Colic Are Not the Same Problem

Owners commonly speak about “gut health” as though the stomach, small intestine and hindgut are one organ. They are not.

Equine Squamous Gastric Disease

Equine squamous gastric disease affects the upper, less protected part of the stomach.

Important management risks include:

• Long periods without forage

• High starch and sugar intake

• Large concentrate meals

• Intense exercise

• Restricted feeding routines

Forage stimulates saliva, provides physical stomach fill and helps reduce exposure of the squamous lining to acidic gastric contents. Exercise can push acidic fluid upwards towards this vulnerable region. (PMC)

Equine Glandular Gastric Disease

Equine glandular gastric disease affects the lower glandular region of the stomach.

It appears to involve impaired mucosal defence, stress, exercise and other factors that are not corrected simply by increasing hay or reducing grain. A horse can have squamous disease, glandular disease, both or neither. (PMC)

Colic

Colic means abdominal pain.

Feeding may contribute to some cases, but it cannot explain every obstruction, displacement, twist, inflammatory condition or age-related intestinal problem.

This is why a horse with recurrent pain should not simply be placed on another supplement or “ulcer diet” without veterinary investigation.

How Much Forage Does a Horse Need?

Most healthy adult horses should receive at least approximately 1.5% of body weight in forage dry matter each day. Many horses do better closer to 2%, depending on body condition, workload, forage quality and health.

For a 500-kilogram horse:

Daily forage target	Dry matter required	Approximate dry hay as fed
1.5% body weight	7.5 kg	About 8.3 kg
2% body weight	10 kg	About 11.1 kg

The final column assumes hay containing approximately 90% dry matter. Actual moisture and nutritional value vary, so hay should be weighed and analysed when precise management is required. (Merck Veterinary Manual)

Free-Choice Forage Is Not Right for Every Horse

Many healthy horses can have near-continuous access to appropriate forage.

That does not mean every horse should receive unlimited rich hay or pasture. Ponies, easy keepers, obese horses and horses with insulin dysregulation may become dangerously overweight or develop hyperinsulinaemic laminitis.

These horses may need:

• Measured low-energy forage

• Tested low-NSC hay

• Slow feeders

• Several divided forage meals

• Controlled pasture access

• A professionally calculated weight-loss plan

The goal is to reduce long fasting periods without accidentally supplying excessive calories.

How Long Can a Horse Go Without Forage?

A study of Danish horses found that forage intervals longer than six hours were associated with increased gastric ulcer risk. Current gastric-ulcer guidance therefore generally recommends avoiding routine forage-free periods exceeding approximately six hours. (PubMed)

This does not mean that a horse missing hay for six hours and one minute will suddenly develop an ulcer.

It means repeated overnight or daytime fasting is an avoidable risk, particularly in horses that:

• Exercise intensely

• Travel frequently

• Have previous squamous gastric ulcers

• Receive starch-rich meals

• Spend long periods stabled

• Become anxious when forage runs out

Check when the hay actually finishes rather than when it was placed in the stable. A net filled at 8 pm is not providing overnight forage if the horse empties it by midnight.

How Large Can a Concentrate Meal Be?

Grain-based concentrate should remain below 0.5% of body weight per meal.

Horse body weight	Maximum grain-based concentrate per meal
250 kg	1.25 kg
400 kg	2 kg
500 kg	2.5 kg
600 kg	3 kg

These are upper limits, not ideal serving sizes. Many horses should receive far less. (Merck Veterinary Manual)

A 500-kilogram horse does not automatically need 2.5 kilograms because that amount falls within the limit. The correct amount may be zero if forage already supplies enough energy.

Starch May Set a Lower Limit Than Meal Weight

The total feed weight does not reveal the meal’s starch load.

For horses at increased risk of squamous gastric disease, consensus recommendations commonly advise keeping starch below approximately:

• 1 gram per kilogram of body weight per meal

• 2 grams per kilogram of body weight per day

For a 500-kilogram horse, this is approximately 500 grams of starch per meal and 1 kilogram daily.

A feed containing 30% starch would deliver 500 grams of starch in approximately 1.7 kilograms of feed, well below the general 2.5-kilogram concentrate ceiling. (PMC)

This is why the relevant questions are:

• How much does the meal weigh?

• How much starch does it contain?

• How much starch and sugar are supplied by the entire ration?

• Does this horse need that amount of energy?

Ask the manufacturer for separate starch and sugar values when they are not printed on the label.

How Often Should Concentrate Be Fed?

A small ration-balancer serving may be divided according to its label.

A horse receiving several kilograms of performance concentrate needs more meals.

Grain-based meals should generally be spaced at least four hours apart. A large daily ration may need to be divided into three or four servings rather than two. (Merck Veterinary Manual)

For example, a 500-kilogram horse receiving 4.5 kilograms of concentrate daily may be better fed:

• 1.5 kilograms in the morning

• 1.5 kilograms during the afternoon

• 1.5 kilograms in the evening

That is usually safer than two meals of 2.25 kilograms, especially when the product is starch-rich.

Better still, review whether part of the concentrate can be replaced with:

• Higher-quality forage

• Beet pulp

• Soy hulls

• A higher-fat commercial feed

• Stabilised rice bran

• Another digestible fibre source

The safest solution may be reducing the total grain requirement rather than becoming extremely efficient at serving it more often.

Should You Feed Hay Before Grain?

Yes, when starch-rich concentrate is necessary, feeding forage first is a sensible strategy.

A 2025 crossover study found that hay before oats delayed gastric emptying of the oat meal and delayed the fall in caecal pH compared with feeding oats first. The study involved only four horses, so it should not be treated as proof that hay neutralises any grain ration, but it supports the practical recommendation to provide forage before concentrate. (PubMed)

A useful routine is:

1. Ensure the horse has not been fasting.

2. Offer forage first.

3. Allow the horse to begin chewing.

4. Feed the measured concentrate meal.

5. Keep forage available afterwards.

Forage first is helpful.

It does not make an oversized starch meal safe.

Should Horses Receive Grain Before Exercise or Transport?

Avoid large grain-based meals immediately before strenuous exercise, transport or another significant stress.

Current feeding guidance advises against meals exceeding 0.25% of body weight during the hour before strenuous exercise or transport. For a 500-kilogram horse, that is approximately 1.25 kilograms. Exhausted horses with reduced gut motility should not be given a large concentrate meal immediately after work either. (Merck Veterinary Manual)

A small forage meal before riding is generally appropriate. Horses are naturally adapted to move while consuming forage.

A large cereal meal is a different proposition.

Do Feed Changes Really Cause 90% of Colic Cases?

No credible evidence supports the claim that 90% of colic cases are linked to a feed change during the previous three days.

Research does show that recent feeding changes are important risk factors. A case-control study identified recent changes in hay batch, grain or concentrate type and pasture exposure as associated with colic. A broader systematic review reached a similar conclusion but also identified housing and other management factors. These studies commonly examined changes occurring during the previous two weeks, not only the previous three days. (PubMed)

The correct message is:

Feed changes matter, but they do not explain every colic.

How Slowly Should Feed Be Changed?

Allow approximately 10 to 14 days for meaningful changes in:

• Concentrate

• Hay type

• Hay batch

• Forage products

• Pasture access

• Major supplements

A practical transition is:

Days	Existing feed	New feed
1 to 3	75%	25%
4 to 6	50%	50%
7 to 9	25%	75%
10 to 14	0%	100%

Sensitive horses may need longer.

Pause the transition if the horse develops:

• Reduced appetite

• Soft or watery manure

• Abdominal bloating

• Intermittent flank watching

• Reduced manure production

• Foot soreness

Hay changes count. Pasture changes count. Moving from one cutting of the same named hay to another can still change fibre, energy, sugar, protein and mineral intake.

Why Is Water Access So Important?

Water supports normal intestinal contents, manure moisture and gastrointestinal motility.

Reduced water intake may occur because of:

• Frozen water

• Dirty buckets

• Malfunctioning automatic waterers

• Unfamiliar-tasting water

• Transport

• Illness

• Dental pain

• Competition within a group

• Electrical leakage from heated equipment

Studies and systematic reviews have associated restricted or reduced water access with increased colic risk. Water intake, manure output and intestinal motility also change with ration composition and feeding management. (PMC)

Do not assess water intake by looking at a large trough and deciding that it still contains plenty.

Measure bucket refills, inspect automatic waterers and confirm that every horse can reach the water without being driven away.

Do Turnout and Movement Matter?

Movement supports normal behaviour, forage intake and gastrointestinal motility.

Recent housing changes and reduced pasture exposure have been associated with colic risk. Horses kept in groups with access to grazing also spend more time feeding and moving than isolated, stabled horses. (PMC)

This does not mean every horse should be turned loose regardless of:

• Injury

• Dangerous footing

• Active laminitis

• Postoperative restrictions

• Pasture sugar

• Social aggression

For a medically confined horse, discuss controlled hand-walking or another appropriate movement plan with the treating veterinarian.

Are Oats and Barley Safer Than Corn?

Not automatically.

Corn, oats and barley are all cereal grains supplying starch. Their energy density, processing and pre-caecal starch digestibility differ, but none becomes risk-free when fed in excessive quantities.

The more useful considerations are:

• Total starch per meal

• Processing

• Meal size

• Frequency

• The horse’s metabolic status

• The balance of the entire ration

A professionally formulated horse feed containing corn may be more appropriate than an improvised ration based on large amounts of oats.

Never Feed Cattle Feed to Horses

The important concern with cattle feed is not simply that it may contain corn.

Some feeds intended for cattle and other livestock contain ionophores such as monensin. Horses are extremely sensitive to these medications, and contamination can cause heart and muscle damage, weakness, colic, sweating, collapse and sudden death. There is no specific antidote. (Merck Veterinary Manual)

Feed only products clearly manufactured and labelled for horses.

Do Probiotics Prevent Colic?

Do not rely on a probiotic to compensate for an unsafe feeding routine.

A systematic review found no clear evidence that probiotic bacteria improve starch or fibre digestion, treat colic or prevent salmonellosis in horses. Results for foal diarrhoea were conflicting, and adverse effects were reported with some high-dose novel bacterial products. (PubMed)

That does not mean every probiotic product is useless.

It means evidence is product-specific and limited. A supplement cannot neutralise:

• A large starch meal

• Dehydration

• Abrupt hay changes

• Long forage gaps

• Dental disease

• Intestinal obstruction

• Active colitis

Fix the feeding routine before attempting to decorate it with tubs.

How Worried Should You Be About Your Horse’s Current Routine?

Lower Risk

The horse:

• Receives adequate measured forage

• Rarely spends more than six hours without forage

• Maintains a healthy body condition

• Has continuous water access

• Receives little or no concentrate

• Has feed changes introduced gradually

• Shows normal appetite and manure

What to do: continue monitoring weight, forage intake, water and manure.

Moderate Risk

The horse:

• Regularly finishes hay several hours before the next feed

• Receives two moderately large concentrate meals

• Is fed by scoop rather than weight

• Has limited turnout

• Has occasional soft manure

• Travels or competes regularly

What to do: weigh the ration, shorten forage gaps and divide the concentrate further.

High Risk

The horse:

• Receives more than 0.5% of body weight in concentrate per meal

• Receives high-starch meals on an empty stomach

• Has previous ulcers, colic or laminitis

• Has abrupt hay or pasture changes

• Drinks poorly

• Is obese or insulin dysregulated

• Shows recurrent appetite or manure changes

What to do: arrange a veterinary and nutritional review before continuing the same routine.

Critical

The horse:

• Has unrestricted access to a grain bin

• Shows repeated abdominal pain

• Has severe diarrhoea

• Produces little or no manure

• Has feed or saliva from the nostrils

• Develops hot feet or a stiff, pottery gait

• Becomes weak or collapses

What to do: seek emergency veterinary care.

When Is This an Emergency?

Call a veterinarian immediately if your horse develops:

• Repeated pawing, flank watching or rolling

• Persistent or worsening abdominal pain

• Marked sweating without exercise

• A rapidly enlarging abdomen

• Refusal of all feed

• Little or no manure

• Pale, dark red, purple or tacky gums

• Weakness or collapse

• Profuse watery diarrhoea

• Feed or saliva coming from the nostrils

• Repeated coughing or difficulty swallowing

• Hot painful feet

• Bounding digital pulses

• A short, stiff or reluctant gait

Colic signs always deserve prompt veterinary advice because owners cannot reliably distinguish a mild gas episode from an intestinal twist or obstruction. (Merck Veterinary Manual)

Grain Overload

Treat accidental access to a grain bin or feed room as an emergency, even if the horse currently looks normal.

Do not:

• Exercise the horse

• Give mineral oil by mouth

• Administer medication unless directed

• Wait for laminitis to appear

• Offer another concentrate meal

Estimate the amount eaten, save the feed label and contact your veterinarian.

Choke

Remove food and water if the horse has feed-stained nasal discharge, excessive salivation, coughing or repeated attempts to swallow.

Do not pour oil or water into the mouth. Material may be inhaled into the lungs.

Laminitis

Acute laminitis is a medical emergency because displacement of the coffin bone can begin quickly.

Hot feet, increased digital pulses, reluctance to turn, short steps or weight shifting require immediate veterinary assessment. (Merck Veterinary Manual)

What Else Can Look Like a Feed-Related Problem?

Not every digestive sign is caused by the current ration.

Important alternatives include:

• Dental disease

• Gastric ulcers

• Parasites

• Sand accumulation

• Intestinal displacement

• Pedunculated lipoma

• Enteroliths

• Colitis

• Salmonellosis

• Equine coronavirus

• Liver or kidney disease

• Gastric impaction

• Oesophageal obstruction

• Toxic feed contamination

• Musculoskeletal pain resembling colic

• Reproductive or urinary disease

A horse may also have two problems simultaneously. A feed change may coincide with an unrelated surgical colic, or dental pain may cause reduced chewing and predispose the horse to choke.

Timing is useful evidence.

It is not a diagnosis.

How Are Gastric Ulcers Diagnosed?

Gastroscopy is required to diagnose gastric ulceration reliably and determine:

• Whether lesions are present

• Whether disease is squamous or glandular

• Severity and location

• Whether another gastric abnormality is present

• Whether treatment has worked

Signs such as girthiness, poor performance, intermittent colic and reduced appetite are not specific enough to diagnose ulcers by themselves. (PMC)

Do not repeatedly treat presumed ulcers while overlooking:

• Saddle fit

• Back pain

• Hindlimb lameness

• Dental disease

• Respiratory disease

• Training problems

• Another gastrointestinal disorder

Girthiness is a useful clue.

It is not a gastroscope.

What Should You Do Next?

1. Weigh the Horse

Use a scale where available or a consistent weight-estimation method.

Meal limits and forage targets cannot be calculated properly from “average-sized horse.”

2. Record Everything Fed for Seven Days

Include:

• Hay

• Pasture

• Concentrate

• Ration balancer

• Supplements

• Treats

• Oil

• Alfalfa

• Beet pulp

• Medication hidden in feed

The unrecorded handfuls still reach the digestive tract.

3. Weigh the Hay and Concentrate

Do not rely on flakes or scoops.

Write the actual weight held by each scoop on the feed bin.

4. Identify the Longest Forage Gap

Check early morning, overnight and between daytime meals.

Shorten routine gaps longer than six hours where practical.

5. Check the Product’s Starch and Sugar

This is especially important for horses with:

• Gastric ulcers

• Insulin dysregulation

• Previous laminitis

• PSSM

• Recurrent digestive upset

6. Calculate Each Concentrate Meal

Keep grain-based meals below 0.5% of body weight and reduce them further where the starch target requires it.

7. Feed Forage First

Provide forage before starch-rich concentrate.

8. Divide Large Daily Rations

Use three or four smaller meals rather than two oversized ones.

9. Confirm Water Intake

Check buckets, troughs and automatic systems directly.

10. Introduce Changes Gradually

Take 10 to 14 days and alter one major feed component at a time.

11. Review Body Condition

The diet should maintain the horse, not merely satisfy a generic feeding chart.

12. Investigate Recurrent Signs

Arrange veterinary examination for:

• Recurrent colic

• Repeated loose manure

• Weight loss

• Poor appetite

• Girthiness

• Choke

• Performance decline

• Foot soreness

Common Feeding Mistakes

Feeding by Scoop

A scoop of oats, corn and a light high-fibre pellet can contain very different weights and calories.

Treating the Maximum Meal Size as a Target

The 0.5% limit is a ceiling. Smaller is usually better.

Allowing Hay to Run Out Overnight

Putting hay in the stable does not guarantee continuous access.

Changing the Hay Overnight

A new batch of the same named hay is still a dietary change.

Giving Large Grain Meals Twice Daily

Convenient for people does not mean ideal for the horse.

Relying on Supplements

Probiotics, buffers and “gut powders” cannot correct fasting, excess starch or dehydration.

Feeding Livestock Products

Horse feed should be clearly labelled for horses. Ionophore contamination from feed intended for other species can be fatal.

Assuming Every Colic Is Nutritional

Diet matters, but delayed investigation of an obstruction or displacement can be catastrophic.

A Practical Gut-Friendly Daily Routine

This is an example for a healthy adult horse that genuinely requires concentrate. It is not a universal prescription.

Morning

• Check appetite, manure and water.

• Provide forage first.

• Feed a small measured concentrate meal.

• Refill water and inspect the automatic system.

• Turn out or provide appropriate movement.

Midday

• Check that forage remains available.

• Provide another small concentrate meal if the daily ration requires it.

• Monitor manure and drinking during hot weather or travel.

Evening

• Provide a measured forage ration sufficient to reduce overnight fasting.

• Feed the final small concentrate meal if needed.

• Check digital pulses in metabolically at-risk horses.

• Confirm the horse is bright and eating before leaving.

Overnight

• Use a safe slow feeder or divided hay stations where necessary.

• Ensure water cannot freeze or run dry.

• Avoid leaving group-housed horses with only one feeding location.

How Can Colic and Ulcer Risk Be Reduced?

• Keep forage at the centre of the ration.

• Avoid routine forage gaps longer than approximately six hours.

• Use measured low-energy forage for easy keepers.

• Feed concentrate only when there is an identified need.

• Keep grain-based meals below 0.5% of body weight.

• Control starch per meal.

• Divide large daily rations.

• Feed forage before concentrate.

• Maintain continuous clean water.

• Introduce changes over 10 to 14 days.

• Maintain safe turnout and movement.

• Keep dental care current.

• Store feed correctly.

• Remove mouldy or spoiled feed.

• Lock the feed room.

• Investigate recurrent signs rather than continually changing supplements.

The strongest digestive-health programme is usually not the one with the most products.

It is the one with the fewest unnecessary disruptions.

Will My Horse Be Okay?

Most horses tolerate sensible feeding routines very well.

The outlook is best when:

• Changes are gradual

• Forage intake is adequate

• Water remains available

• Concentrate meals are small

• Body condition is appropriate

• Early warning signs are recognised

A horse with mild manure softening after a change may return to normal when the transition is paused.

A horse with persistent pain, major appetite loss, absent manure, profuse diarrhoea, choke signs or foot soreness needs veterinary assessment rather than another ration adjustment.

The real danger is not one imperfect feeding day.

It is repeatedly ignoring the pattern that says the horse is no longer coping.

FAQs About Horse Feeding Routines

How often should a horse be fed?

Forage should be available frequently enough to avoid long fasting periods. Concentrate frequency depends on the daily amount, but larger rations should generally be divided into at least three or four meals spaced several hours apart.

Is two grain meals per day safe?

It may be safe when the total amount is small and each meal remains comfortably below the horse’s starch and weight limits. Two large meals are much more concerning.

Should hay always be fed before grain?

Feeding forage before starch-rich concentrate is a sensible strategy and may delay gastric emptying and the resulting caecal pH change. It does not neutralise an excessive grain meal. (OUP Academic)

Can a horse still develop ulcers with constant hay?

Yes. Consistent forage reduces important squamous-ulcer risks, but exercise, stress, disease, medications and glandular mucosal problems can still cause gastric disease.

Do probiotics prevent colic during a feed change?

Evidence does not show a clear preventive effect. A probiotic should never be used as permission to change feeds rapidly. (PubMed)

Final Thoughts

A gut-friendly feeding routine is not complicated, but it does require consistency.

The main rules are:

• Feed enough appropriate forage.

• Avoid prolonged fasting.

• Use concentrate only when needed.

• Keep meals small.

• Control starch.

• Feed forage first.

• Change hay, pasture and concentrate gradually.

• Keep water available.

• Monitor the horse rather than merely following the bucket schedule.

Good feeding can reduce important risks.

It cannot prevent every ulcer, obstruction, displacement or colic. That is why recurring symptoms still need diagnosis rather than another supplement and a hopeful pat on the neck.

The best ration is not the one that looks most impressive in the feed room.

It is the one that quietly keeps the horse eating, drinking, passing normal manure, maintaining healthy condition and getting on with being a horse.

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If your horse has recurrent colic, appetite changes, loose manure or suspected gastric ulcers, ASK A VET™ can help you organise the feeding history and warning signs while your local veterinarian provides gastroscopy, examination or emergency treatment when hands-on care is needed.