Acid buffers – Do they really work? Could your horse’s health benefit?

When your horse suddenly starts acting girthy, pins their ears during grooming, becomes reluctant to work, or goes off their feed, you should take a look at their diet. The culprit may be ulcers caused by stomach acid "splashing" in the stomach. 

Below, we explore the digestive and environmental issues that lead to ulcers and reveal how a digestive supplement may help buffer the stomach acid that plays a role in ulcer formation.

How does the horse’s stomach actually work?

There is a key difference between the human stomach and your horse’s stomach: horses are grazing animals that evolved to graze constantly and digest food continuously. The horse’s stomach continuously secretes acid—even when they are not eating! This stomach acid helps to break down what the horse eats.

horse digestion natural grazing

However, in a domestic setting, we keep horses in different environments. We confine them to paddocks or keep them in stables. In these settings, the horse is often without access to quality grazing. This is problematic for the horse’s stomach, as it allows their stomach acid levels to rise.

Why roughage is essential for the horse’s stomach

Allowing your horse to eat roughage continuously is the number one thing you can do to help prevent stomach ulcers. Roughage is most effective in the form of pasture or hay. And although “super fibres” can be supplemented into your horse’s feed, they should not be your horse’s primary source of roughage. Horses need the bulk of their roughage to be long-stem, which stimulates the digestive system and takes time to eat. Without adequate roughage, the risk of horses developing ulcers increases significantly.

The minimum amount of roughage for horses is 1.5% of their body weight per day. Bodyweight (in kgs) x 0.015 = kgs of roughage per day.

How to feed roughage with pasture

If your horse has access to good quality pasture then it will be able to meet its roughage requirements by grazing. This is the ideal scenario that permits them to graze as needed, and keep their digestive “wheels turning.”

However, if the pasture is poor in quality or there are bare areas, multiple patches of weeds, or places where your horse is not grazing, then the question of whether your horse is meeting its roughage requirement is harder to answer and it’s likely you need to supplement pasture with hay.

Horse hay roughage

How to feed roughage without pasture (or with poor-quality pasture)

Limited pasture, or the complete absence of pasture, is a problem that many horse owners face. Thankfully, by supplying your horse with a minimum of 1.5% of its body weight in kg of good quality hay per day, you can keep their stomach acid within the healthy range.

You should weigh your hay in order to gain an understanding of what 1.5% of a horse’s bodyweight looks like. This easy exercise can be an eye-opening experience! It’s easy to underestimate your horse’s requirements and leave them short-changed on roughage.

Another good indicator is to look for leftover hay from the previous feed; if your horse has finished all of its hay, then there’s a good chance it is standing around with an empty stomach. Remember—we want horses to always have access to roughage to ensure they are utilizing their stomach acid!

If your horse is finishing all of their hay between feeds, you can help keep them occupied by,

  1. Feeding more hay;
  2. Utilizing a slow net feeder to slow down their eating and make the hay last longer. This is a good option for horses that consume their hay a little too quickly. It’s also handy for horses that may be overweight and shouldn’t have their hay increased.

What causes ulcers in horses?

Remember when we mentioned horse’s natural grazing behaviour? Millions of years of grazing evolved a stomach that is conditioned to always have something in it. As a result, the upper half of your horse’s stomach (called the non-glandular region) is unprotected from stomach acid, because for countless generations, there wasn’t risk of contact because the stomach always had something in it and acid production was not excessive.

Stomach acid builds up when your horse’s stomach is empty and the acid can actually splash up onto the top half of the stomach. When acid splashes onto that upper half it can burn the area and cause ulcers. As you can imagine this is quite painful and can affect your horse’s general well-being, performance, and behaviour. The upper half is shielded from acid when their stomach has something in it because, when they’re eating, the feed physically “mops up” some of the acid and prevents splashing by forming a physical barrier. 

Stress also plays a part in ulcer formation. The modern horse is exposed to an endless parade of stressful situations: competitions, floats, paddock changes, location changes, stabling, etc. It is difficult to avoid stress in the modern horse’s life!

Stressed horse

The role of acid buffers in helping to prevent ulcers

To combat rising stomach acid, we can look at adding something to your horse’s diet that acts as a buffer. An acid buffer is a product that is able to raise the pH of the stomach contents, i.e., make it less acidic/less damaging. One of the most common acid buffers in equine nutrition is calcium.

There are a few options at our fingertips that are high in calcium:

Lucerne hay/chaff is a popular option because it’s readily available. It can be used as a pre-ride or pre-float meal to add some calcium into the stomach to buffer acid and to act as a physical barrier to prevent that acid from splashing.

Lithothamnion calcareum (LC) or Red Seaweed is a more technical option. LC is an additive that can be found in selected equine feeds, like HYGAIN® VICTORY®, and supplements, such as HYGAIN® DIGEST & PROTECT®, to help buffer stomach acid. LC has a high mineral content that includes magnesium, as well as high levels of calcium.

The structure of LC is also notable because it resembles honeycomb, which provides a greater surface area to interact with stomach acid. This makes it a highly effective acid buffer in horses. LC has demonstrated a buffering effect in horses that lasts between 2-4 hours after consumption.

Which horses may benefit from an acid buffer in their diet?

The protective properties of an acid buffer make it relevant for a wide range of horses. To decide whether an acid buffer may benefit your horse, ask yourself the following questions:

  • Are they prone to ulcers?
  • Are they girthy?
  • Are they in a stressful environment – competing horses, travelling horses, etc.?
  • Are they able to graze on roughage all day?

How do I add an acid buffer into my horse’s diet?

Look for a supplement that supports your horse’s complete digestive well-being. Supplements like DIGEST & PROTECT® are formulated with lithothamnion calcareum (LC) which is an effective acid buffer. Coupled with pre- and probiotics for digestive support, and ingredients like slippery elm that help coat the stomach, the ingredients in DIGEST & PROTECT® create a holistic digestive supplement which targets digestive health from start to finish. DIGEST & PROTECT® is highly palatable and can be added directly into your horse’s current diet.

 Digestive support for horses

HYGAIN® DIGEST & PROTECT® provides complete digestive support in a palatable blend, formulated to stimulate digestion and promote the health of the digestive tract.

The formulation of DIGEST & PROTECT contains:

RED SEAWEED EXTRACT (Lithothamnion calcareum), is rich in a specific, highly effective source of calcium, known for its superior acid buffering properties.

DIGESTIVE ENZYMES support the breakdown of feed which improves digestion and the absorption of nutrients.

GLUTAMINE & THREONINE, amino acids assist with digestive health. Included to ensure adequate supply to support mucin synthesis and cell regeneration.

CONCENTRATED SLIPPERY ELM traditionally used for gastric challenges. Slippery Elm contains mucilage factors which act as a coating agent.

CURCUMIN, is the active compound in Turmeric known for its powerful antioxidant action.

PREBIOTICS have a defined mode of action, promoting a healthy gut and supporting natural defences essential for optimum health and performance.

PROBIOTICS enhance fibre fermentation and stablilise the microbiome, stimulating activity of beneficial bacteria in the digestive tract.

MYCOTOXIN BINDER traps and expels mycotoxins to protect and support healthy gut function.

ANISEED flavour is highly palatable for horses.

Equine digestive supplement


If you’re unsure if your horse is at-risk of gastric upset or if they’re already exhibiting symptoms of ulcers, our team can help. Our Nutrition Advisors at Nutrikey offer a free diet analysis that is simple, fast, and accessible to all levels and disciplines of horse owners. The team will review their current diet, considering all of their lifestyle and lifestage factors, and will provide a diet plan that will help them look and feel their best for years to come. Visit or reach out to


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Colyer, M, M, O’Gorman, D, M & Wakefield, K 2014, ‘An in vitro investigation into the effects of a marine-derives, multimineral supplement in simulated equine stomach and hindgut environments’, Journal of Equine Veterinary Science, vol. 34, no. 3, pp. 391-397.

Jacobs, R, D, Gordon, M, B, E, Vineyard, K, R, Keowen, M, L, Garza Junior, F & Andrews, F, M 2020, ‘The effect of a seaweed-derived calcium supplement on gastric juice pH in the horse’, Journal of Equine Veterinary Science, vol. 95, pp. 103265.

Liburt N, Mastellar, S, Cassill, B, Schmutz, A & Harris, P 2021, ’68 effect of a marine-sources calcium on fecal pH in horses’, Journal of Equine Veterinary Science, vol. 100, 103531.

Moir, T, O’Brien, J, Hill, S, R & Waldron, L, A 2016, ‘The influence of feeding a high calcium, algae supplement on gastric ulceration in adult horses’, Journal of Applied Animal Nutrition, vol. 4, e.8.

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