Prebiotics vs Probiotics vs Postbiotics - Which are best for horses?

We Look at What Horses Really Need for a Healthy Gut

If you are interested in equine gut health, you’ve likely seen the terms prebiotics, probiotics, and postbiotics on labels and adverts. They sound similar, but each plays a very different role in your horse’s digestive system. Understanding how they work (and when to use them) helps you choose the right equine digestive supplement, horse gut balancer, or hindgut supplement with confidence.

Quick definitions 

• Prebiotics for horses
  Non-digestible fibres and plant compounds that feed beneficial microbes in the hindgut. Think MOS (mannan-oligosaccharides), FOS / inulin (from chicory), and certain soluble fibres like pectin and psyllium. Horses can’t digest them - but microbes can, turning them into health-supporting short-chain fatty acids (SCFAs).
• Probiotics for horses
  Live, beneficial microorganisms—most commonly yeast (e.g., Saccharomyces cerevisiae) given to support a balanced microbial community and steady fermentation.
• Postbiotics for horses
  These are beneficial compounds that are produced by gut microbes (think fermentation metabolites, cell wall fragments, peptides, and SCFAs) that can support the gut lining, immune signalling, and barrier function - without needing live bacteria. Some modern formulations deliver yeast-derived postbiotic fractions directly.

Each of the tribiotics targets a different step in the gut ecosystem: fuel the good guys (pre) → add good guys (pro) → benefit from what the good guys make (post). But as we will explain further below, it is the availability and variety of prebiotics that matters most.

Why the hindgut matters

Horses are hindgut fermenters. The cecum and colon house a vast community of microbes that turn fibre into energy (volatile fatty acids like acetate, propionate, butyrate) and synthesise vitamins. When the hindgut is stable, you can see better fibre digestion, calmer behaviour, stronger immunity and more consistent performance. If the hindgut is upset by things like sudden diet changes, high-starch meals, stress, travel or injury - you may see loose droppings, gas, bloating, girthiness, dull coat, or decreased rideability. That’s where targeted horse gut health support can help.

Prebiotics: the daily “feed” for beneficial microbes

How they work

Prebiotics pass undigested to the hindgut, where beneficial bacteria ferment them. This produces SCFAs—especially butyrate, which is a preferred fuel for colon cells and helps maintain mucosal barrier integrity. Prebiotics can also inhibit pathogen attachment to the gut wall (MOS binds certain undesirable bacteria) and stabilise pH by favouring fibre-friendly microbes.

What to look for

• Named ingredients and stated levels: MOS, FOS / inulin, chicory root, psyllium husk, pectin. Ask the manufacturer if you are not sure.
• Blends: A wide variety of plant fibres can broaden microbial diversity in the hindgut - useful when undergoing pasture changes or when hay supply is inconsistent. Horses evolved to eat 40 different plant fibres a day and modern management’s restriction on fibre diversity intake impacts hugely on gut health and overall wellbeing.
• Low sugar & starch: Important for good-doers and ulcer-prone horses.

When prebiotics help most

• Transitioning hay/grass, moving yards, traveling/competing and when staying away at shows
• Horses on restricted grazing where plant diversity is limited
• Good-doers: a hindgut supplement centred on a variety of prebiotic fibres supports microbiome health without adding unnecessary calories

Owners often search for a horse gut balancer when they notice inconsistent droppings, gas, or mild behavioural tension. A prebiotic-rich equine digestive supplement like Gut Food can be a smart first step.

Probiotics: live microbes for fermentation stability

How they work

Probiotics introduce beneficial yeast or bacterial strains to help stabilise hindgut fermentation, especially after periods of illness, surgery, worming or after anti-biotic treatment – all of which can negatively affect hindgut microbiome colonies. Well-researched yeast strains can enhance fibre breakdown and buffer hindgut pH.

What to look for

• Strain specificity and CFU count at end of shelf life (not just at manufacture date)
• Evidence-led strains for horses, Saccharomyces cerevisiae yeast (more commonly known as brewers yeast) is most widely used
• NOPS-accredited manufacturing for competition horses

When probiotics help most

• Concentrate-fed horses or those in hard work with limited access to pasture/diverse plant fibres
• During/after antibiotic therapy (in consultation with your vet)
• After stressors that can disrupt appetite or routine (transport, multi-day shows)

A word of caution. Adding more bacteria to a compromised gut has been shown in human studies to have negative effects so you may find that your horse’s symptoms worsen when fed probiotics. It is important to remember that all gut bacteria requires an adequate food source. If your horse’s gut is struggling to sustain the existing good bacteria population, adding more bacteria will at best produce a short-term benefit and at worst may exacerbate their symptoms, as shown in human studies. Prebiotics are the food for bacteria to survive and thrive on. Focus on providing a diverse range of quality prebiotics to support a healthy gut environment before adding more bacteria. 

Postbiotics: benefits without live bacteria

How they work

Postbiotics deliver bioactive components from fermentation—like peptides, beta-glucans, mannans, organic acids, and SCFAs—that support immune signalling, barrier function, and balance in the gut. Because they aren’t live organisms, postbiotics are stable, safe, and consistent.

What to look for

• Clearly named postbiotic sources (e.g., yeast culture, fermentation extract, beta-glucan rich yeast fractions)
• Complementary formula that includes prebiotic fibres to feed your horse’s existing microbes

When postbiotics help most

• Performance horses managing travel, stabling, and training stress with limited access to diverse pasture/forage
• Horses that don’t tolerate certain live bacteria well—or when you want shelf-stable gut support year-round

Postbiotics are the product of hindgut fermentation when the good bacteria digest the prebiotic fibres. Don’t fall for clever marketing or quick fixes – cut out the middle man and provide high levels of diverse, prebiotic fibres in your horse’s daily feed – then their gut will produce the postbiotics and beneficial compounds/SCFA’s directly!

How to choose: prebiotic vs probiotic vs postbiotic

Use this cheat sheet to match goals to tools:

Goal / Scenario	Best first choice	Why
Day-to-day gut resilience & diversity	Prebiotics (+ postbiotics as a result)	Feed and stabilise beneficial microbes; diversify fermentation
After stress, illness, surgery, worming and/or antibiotic treatment	Probiotics + prebiotics	Add helpful microbes and give them fuel
Good-doer on restricted diet	Prebiotic-rich hindgut supplement	Supports microbiome without extra calories
On high levels of concentrates / in hard work with limited access to pasture	Probiotic yeast + prebiotic fibres	Helps fibre digestion and pH balance

 

Notice that prebiotics appear in every scenario? In reality, the best horse gut supplement will focus on providing a wide range of prebiotics as the most important part of long term gut health and resilience.

What good results look like

With the right equine gut health plan, owners often notice:

• More consistent droppings, less wateriness or acrid smell
• Calmer, more forward rideability - the gut–brain axis is real!
• Improved coat and condition from better nutrient utilisation
• Steadier appetite and recovery during show season.

Track changes for 2–4 weeks after introducing a new equine digestive supplement and keep other variables (forage, workload) as steady as possible.

Label checklist (so you can compare with confidence)

• Clear ingredient names and amounts e.g., MOS mg/serve, inulin grams, yeast strain + CFU. Ask the manufacturer if you are unsure and if the amounts are not stated, question whether they are there in effective, useful amounts.
• Low sugar & starch; fibre-first carriers. Avoid ingredients like dextrose where possible.
• Evidence-informed strain or fibre choices; wide variety for hindgut diversity
• NOPS/UFAS assurance for competition use
• Palatability and sensible daily serving size (consistency wins)

FAQs

Are probiotics or prebiotics better for horses with gastric ulcers?
Ulcers are a medical condition - speak to your vet. Generally, a forage-first, low-starch diet alongside prebiotic fibres and soothing compounds (e.g., pectin, lecithin and specific plant extracts) is best for horses with ulcers. Probiotics can be useful, especially yeast, to keep hindgut fermentation steady but human studies have shown that adding bacteria (probiotics) to compromised gut systems can exacerbate the issues rather than helping. Consult your vet if you have concerns.

What is the best supplement for horses with ulcers?

Gastric ulcers require veterinary diagnosis and treatment. Once clear, a quality gut supplement can be a useful tool for maintaining a healthy gastric environment long term. Look for meaningful levels of lecithin and pectin in the daily serve. These two ingredients have been shown in clinical studies to create a hydrophobic barrier in the stomach, building on the horse’s natural defence mechanisms against acid splash on the delicate stomach mucosa. Antioxidant support (eg. natural vitamin E, grapeseed, rosemary extract) help with maintaining healthy cells and tissues whilst natural anti-acid ingredients can support a stable PH within the stomach. Soluble fibres and prebiotics will provide food for the hindgut “good guys”.

Can I feed prebiotics and probiotics together?
Yes—this is often called a synbiotic approach. Prebiotics provide the fuel; probiotics provide the strains. A healthy gut does not need additional bacteria and a gut that does have not sufficient feed (prebiotics) for the existing colony of microbes will not be able to sustain additional bacteria numbers, so quality prebiotics are essential for optimal gut health. Adding bacteria (eg. Saccharomyces cerevisiae – also known as brewers yeast) alone will not solve the problem.

Do postbiotics replace probiotics?
Not necessarily. Postbiotics shine for stability and immune/lining support. Many owners layer them with pre/probiotics for a rounded plan. The more prebiotics you have available, the better the fuel source for the bacteria within the gut and those bacteria will naturally produce postbiotics themselves, as well as multiplying in number. So the quality of prebiotic gut food provided is extremely important to support microbiome diversity and encourage good bacteria proliferation. The more prebiotics available, the more postbiotics and beneficial compounds/SCFA’s the bacteria will be able to produce after fermenting the food!

Putting it into practice

1. Start with forage: good-quality, consistent hay; avoid big starch spikes.
2. Add a balanced gut formula that fits your horse’s situation, focusing on providing a wide variety of prebiotic fibres as the most important part of that formula. Remember wild horses eat 40 different plant fibres a day. Check the labels, how many different plant fibres is your horse eating each day?
3. Introduce gradually over 5–7 days.
4. Monitor droppings, appetite, rideability, and coat; adjust one thing at a time.
5. Careful management is key: slow-feeding and minimal time without forage, stress reduction, adequate turnout, clean water, rest days and sensible use of medications.

The bottom line

Prebiotics, probiotics, and postbiotics are different tools used to achieve the same goal: a stable, diverse hindgut that powers health, behaviour and performance. The most effective horse gut balancer or best equine digestive supplement typically blends these approaches to feed the right microbes, seed when needed and deliver the beneficial compounds those microbes produce. Choose a product with clear ingredients, meaningful levels, and NOPS accreditation, then pair it with consistent, forage-first management and a low stress environment. That’s how you build equine gut health that lasts - season after season.

The Equell Team, 12.9.25