No Guts No Glory – How horses turn food into fuel

No Guts No Glory – How horses turn food into fuel

No Guts No Glory – How horses turn food into fuel

Sam Potter - Bachelor of Equine Studies (Hons), Master of Philosophy in Veterinary Science (Equine Nutrition)


Understanding the process of your horse’s digestion, will help you understand how lifestyle and diet may impact them. The horse is designed to thrive on a diet of mainly forage, the same way a petrol-powered car is designed to run on petrol. Likewise, without the right fuel, your horse won’t run efficiently and performance will be affected.

However, unlike a car which you fill up when the fuel tank is empty, your horse is is designed to graze most of the day to maintain their fuel tank level. This is because horses turn the fibrous component of forage (the fuel) into energy through the slow process of fermentation. Fermentation occurs in a horse’s hindgut and involves fibre-digesting bacteria turning the fuel into energy - just like the engine of a car converting petrol into energy.  And just as crude oil undergoes a process called refining to make petrol, forage also undergoes various processes to make the fuel suitable for our horse when it reaches the hindgut.

This process starts with chewing. Chewing mechanically grinds the feed into smaller particles and promotes saliva production.  Saliva coats the feed, lubricating it to help it travel down the esophagus into the stomach and also contains bicarbonate which aids to buffer acid in the stomach.

Quick facts:

  • A horse takes approximately 4000 chews to consume one biscuit of hay
  • A horse can secrete about 10 litres of saliva a day

Once the feed enters the stomach it is mixed with gastric acid which is secreted from the lower glandular portion. Gastric or stomach acid is continually produced (up to 60 litres per day) and contains enzymes which start the digestion process as well as kill pathogens. The lower portion of the stomach is protected with mucus, yet the upper non-glandular section isn’t.

Due to the size and constant secretion of gastric acid, your horse’s stomach is designed to have feed, particularly forage, continually entering it. If the stomach becomes relatively emptied and a horse is exercised, the accumulation of gastric acid can freely splash onto the upper unprotected area, damaging the mucosa and resulting in gastric ulcers. One way to avoid this is to have some hay hanging whilst you are saddling up, so they can have a forage buffer in their stomach.

Quick facts:

  • Your horse’s stomach is about the size of a rugby ball and holds about 2-3 kilograms of food.
  • When it is about two thirds full it starts to push food through to the small intestine.

The next step of digestion involves the small intestine and digestive enzymes. They breakdown starch, fat and protein in the small intestine and allow nutrients to be absorbed. They pass through an intact gut wall (which is joined by tight junctions to avoid other unwanted molecules getting in) and into the horse’s system. The small intestine is about 21 m long and is only called the small intestine due to the diameter of it.  It is nearly the length of half an Olympic swimming pool, so it’s anything but small.

Food can generally take 3-4 hours to pass through the small intestine, but it can be known to move through here in as quickly as 30 minutes which is not ideal. When food moves through too quickly, there is less time for the digestive enzymes to work which results in undigested starch, fat and proteins landing in the hindgut, a place pretty much reserved or fibre.

When a horse has restricted grazing or access to food and the small intestine is empty for long periods of time, the horse is more susceptible to problems such as colic.

The leftover fibre then moves into the incredible hindgut, where the magic happens. The hindgut is simply part of the horse’s digestive system. The first part of the hindgut is called the caecum, and is the place where both good and bad bacteria live. It is almost incredible to think that this number is over 100 trillion bacteria. The caecum sits on the right-hand side of the horse and can increase up five times in size. Many riders report having more difficulty flexing and canter transitions to the right, which may be due to an inflamed and irritated caecum.

The “good bacteria” perform the role of fermenting the fibre (examples include grass, hay, beet fibre, fibrefresh etc) into energy for your horse, as well as amino acids, B vitamins and Vitamin K. In fact, up to 70% of your horse’s total energy requirements come from good bacteria eating fibre, not from grain.

The “bad bacteria” on the other hand love to ferment starch and sugars(from grain) which in turn create lactic acid – too much lactic acid can lead to an acidic hindgut.

The process continues with movement of food into the large colon where fermentation continues and the small colon where water is reabsorbed and then into the rectum and is eventually passed as manure.

During periods of man-made stress, such as stabling horses, feeding them twice daily, consuming a high grain diet, providing limited time or availability of pasture and limiting food choices, will affect the type, the motility and the volumes of food moving through the intestines. This will affect the digestive process, the processing and absorption of nutrients, and most importantly the movement of starches into the caecum and colon of the hindgut.

Excess starch from the diet may lead to increased lactic acid production and an unfavourable shift in the gut microbiota – i.e. the bad bugs proliferate and out compete the good bugs. This shift in the microbiome can lead to toxins being produced in the gut of the horse and further compromise the health, performance and recovery.  These stress events may lead to an acidic hindgut, where damage and irritation to the gut wall can occur allowing toxins to move from the gut and into the blood system, resulting in systemic inflammation.  This could result in laminitis, colic, behavioural issues, hind gut inflammation, reduced performance, appearance, hoof growth and other problems.

Additionally, stress events and a high grain diet can negatively impact on the stomach. Stress and the ingestion of grain can stimulate the release of a hormone called gastrin which stimulates gastric acid production. This excess gastric acid and periods of no food in the stomach can irritate the gut lining leading to gastric ulcers.

Check out Stress Paste.

The reality is that domesticated horses and racehorses will continue to be under stress which will result in a compromised digestive process and nutritional and energy benefit.

Digestive RP is specifically suitable for horses on a higher grain diet has been designed to provide extra support for the digestive processes so as to increase the horse’s resilience and ability to cope with stress by stabilising the pH of the Digestive system.