Let’s talk Gut Health

‘Gut Health’ has become an increasingly discussed topic in Equine Nutrition, and with good reason. The horse’s gastro-intestinal tract is designed to be metabolising fibre for 16 – 18 hours per day, relying on a complex population of micro-organisms that play an essential role in fermenting fibre, whilst maintaining and regulating normal digestive function.

Why is Gut Health so important?

The equine gastro-intestinal tract is particularly well adapted to metabolising fibre. Digestion takes place in the hindgut, which is resident to billions of microorganisms, whose role it is to ferment fibre and in turn, to extract nutrients from that fibre (to produce energy), to synthesise vitamins and finally, to interact with the immune system.

Maintaining a healthy and stable microbial population is therefore an important part of supporting normal digestive function.

Sudden changes to diet, be that fibre or concentrate rations, periods without access to forage, stress, traveling, illness and some medications, can all affect the gastrointestinal tract.

Good ‘gut management’ starts with the basics:-

• Plenty of appropriate forage,
• Regular access to fibre and water,
• Gradual dietary changes.

Why is Gut Health important right now?

At this present time of year, the Autumn brings with it several seasonal changes. Firstly, the change in temperature and the abundance of rain and sun, mean that there is plenty of fresh, lush Autumn grass. Secondly, the change has occurred reasonably quickly.

Looking at the list above, this, in effect, means that the present Autumn-flush grass now, might not be appropriate for many horses (particularly those at maintenance or in light work) and equally important, the changes in the grass have not occurred gradually.

Typical ‘Autumn’ grass digestive upset symptoms include loose droppings, referred to as hindgut ‘dysbiosis’. Essentially, this is an imbalance in the microbial population of the caecum and colon (i.e., the hindgut), where the beneficial fibre-digesting microbes decline and harmful or acid-producing bacteria take over. As well as loose droppings, other symptoms may include a variable appetite, poor weight maintenance, alternating or chronic diarrhoea / free faecal water syndrome, bloating, recurrent mild colic, behavioural changes or poor athletic performance.

How best to support Gut Health

There are three main supplementation routes to provide maximum hindgut health support for your horse. These are via probiotics, prebiotics and post-biotics.

1. Probiotics

The relationship between the horse’s hindgut and the microbial population that exist there is complicated. Research has found that interactions between the horse’s immune system and the bacteria colonising it, can have a profound effect on the overall health of the equine.

Put more simply, probiotics are live organisms that are intended to provide beneficial effect when provided in the ration in appropriate amounts. Typically, they consist of specific strains of bacteria (namely, the Saccharomyces cerevisiae strain or yeast), and are designed to support equine digestive health, specifically, by improving fibre digestibility and also, buffering acid pH levels.

2. Prebiotics

Prebiotics are complex carbohydrates or soluble fibres, which cannot be digested in the small intestine. They are instead, fermented in the hindgut, specifically in the cecum and colon.

All prebiotics work by supporting the proliferation of probiotic strains of bacteria. However, some also seem to have a direct effect on the immune system.

Beta-1,3/1,6- glucans are complex carbohydrates from the cell wall of yeasts such as Saccharomyces. A 1999 study in broodmares concluded that there was a positive immunostimulatory effect in the broodmares injected with these glucans. They documented higher antibody levels in their colostrum. Studies on effects, when given orally, are not available for horses but this substance reliably stimulates the immune system in other species when supplemented orally. (L Krakowski, et al., 1999)

Any high soluble fibre food ingredients can serve as a ‘prebiotic’ by “feeding” the hindgut microbial population. Examples include beet pulp, psyllium and micronised linseed meal.

3. Postbiotics

The equine hindgut microbiome population produces over 1,300 metabolite (defined as, ‘any small molecule produced, consumed, or left over during metabolism’) chemicals during the fermentation stage of the digestive process – The chemicals formed during this fermentation process are postbiotics.

Postbiotics, similar to prebiotics, are non-living microorganisms that have several health benefits to a horse’s gastrointestinal tract. However, postbiotics can also be derived from living organisms, such as probiotics, but always contain a mixture of unpurified inanimate organisms that include their metabolites.

To put it more simply; postbiotics are what’s left behind after a horse is finished digesting prebiotics and probiotics. In fact, they are produced by a combination of prebiotics and probiotics in the hindgut. Examples of ‘postbiotic’ nutrients are amino acids, B-vitamins and Vitamin K.

The production of postbiotics depends on the quality and variety of the horse’s diet, as well as the unique microbial strain makeup in their hindgut. The quality of the ration that the horse is consuming has a direct connection to the quality of what’s left over after the digestion and fermentation process is complete.

An unhealthy gut biome leads to issues with the production of postbiotics, which can lead to other issues, like disease and deficiency.

4. Synbiotics

Synbiotics are supplements that contain combinations of prebiotics and probiotic bacteria and/or yeasts. They are marketed and promoted for use in supporting and enhancing equine digestion, which in turn can, enhance athletic performance, as well as reducing stress and other factors. (C. Cooke, et al., 2023)

The Bottom Line

Probiotics, prebiotics and postbiotics can all have a place within equine nutrition, but they aren’t automatically necessary for every horse.

As previously outlined, equines having difficulty holding weight, in poor condition, or having a gastrointestinal issue such as gas, diarrhoea or fluid (with / without normal faeces) could all be suitable candidates for supplementation. However, it must also be highlighted that there are other possible causes for those issues.

The most important part of any equine’s ration is forage and maintaining a consistent supply of appropriate fibre is fundamental to digestive health. Therefore, it’s important to remember the ‘basics’:-

• Is your horse receiving enough appropriate forage?
• Are forage and concentrate feeds changes being made gradually?
• Is your horse’s ration appropriate for their workload and body condition?

A healthy gastrointestinal tract starts with appropriate forage, good feeding practices and consistent management. Supplementation should be considered on an individual basis.

When it comes to gut health, supporting your horse’s gastrointestinal tract naturally through balanced nutrition and management should always come first.

References

• Anim Sci., ‘The influence of a probiotic/prebiotic supplement on microbial and metabolic parameters of equine cecal fluid or fecal slurry in vitro’. MacNicol et al., 2023
• Am Vet Med Assoc., ‘Efficacy of Saccharomyces boulardii for treatment of horses with acute enterocolitis’. Desrochers et al., 2005.
• ForagePlus Talk, Probiotics and Prebiotics for Horses, E.M. Kellon, 2023
• Int Journ of Equine Sci., ‘Prebiotics and Synbiotics in Equine Health and Disease: Probiotics and Synbiotics for Horses’. C Cooke, et al., 2023
• Vet Immunol Immunopathol, ‘The effect of nonspecific immunostimulation of pregnant mares with 1,3/1,6 glucan and levamisole on the immunoglobulins levels in colostrum, selected indices of nonspecific cellular and humoral immunity in foals in neonatal and postnatal period’. Krakowski et al., 1999.