What Happens When Your Horse Eats

What Happens When Your Horse Eats | Equine Digestion

Your horses’ digestive system is a complex and unique system that requires careful management to keep it healthy and to function correctly. How, when and what he or she eats all play major factors in healthy gut function. In this feature What Happens When Your Horse Eats | Equine Digestion, our Han Van De Braak BSc LicAc MCSP MBAcC (Retd.) explains what happens from your horses first chew and beyond.
Your horse’s digestive system is a fantastic creation: If you could lay it out in its entirety it would measure around 100 feet in length and on average take between 36 – 72 hours for the entire digestive process to complete! Let’s take a look at the process…


Your horse can only chew on one side of his mouth at anyone one time. Horses chew from outside to inside, rather than up and down as humans eat. Your horse has three glands in his mouth which can produce up to ten gallons of saliva a day. Saliva contains salivary amylase, an enzyme that breaks down starches and in this way protects the horse from tooth decay. Optimal saliva pH is 6.7 – 7.0 (neutral) which may help to ‘buffer’ the acidity in their stomach. As horses (and humans) age, their saliva becomes less alkaline (the breakdown of carbohydrates into lactic acid, butyric acid and aspartic acid) this can contribute to the risk of getting gastric ulcers. Saliva has a protective function for your horse’s mouth as it breaks down what oral pathogens need to feed (and breed).


Once your horse has chewed his feed and swallowed it heads down into the horse’s oesophagus. The oesophagus can be around sixty inches in length and only allows food to lead one way – directly to the stomach, so, indeed, horses cannot vomit.


Your horse’s stomach is relatively small in comparison to the other parts of his digestive system. Food retention in the stomach is only around 15 minutes (which would explain the size of your muck heap!) before it heads into the small intestine. When the stomach is empty, acid attacks the squamous cells (this is also where good saliva production is also essential in neutralising the acid that ends up in his tummy).


The small intestine is where most of the digestion occurs. Proteins are broken down into amino acids, fat-soluble vitamins A/D/E/K, inorganic minerals, starches, solid carbohydrates and saccharides are absorbed. Because the horse is a trickle feeder, it does not need a gall bladder; bile flows directly into the small intestine to aid in the digestion of fats. Because horses do not have gallbladders and the sphincter of the common bile duct is weak, continuous secretion of bile into the intestine has been documented, and enterohepatic circulation occurs 38 times per day. There is no statistical difference between bile acid concentrations in ponies and horses. The reason why horses do not need a gallbladder is because they are constant grazers, so no need for a reservoir that delivers as and when it is eating. From there, the food enters and exits the cecum.


The Caecum can hold up to 10 gallons of food and water and a population of bacteria and microbes, which further break down food (fibre) for digestion and absorption. These microbes are accustomed to digesting a horse’s ‘normal’ diet, so any adjustments in feed or forage should be made slowly, allowing the microbes to adjust. If a horse consumes too much starch in one meal, it is unlikely to be digested fully in the small intestine. It would pass through the small intestine into the cecum where the microbial organisms rapidly ferment the starch, producing excessive gas and lactic acid that could ultimately cause digestive upset or colic.


The next stage for the food to pass through the large intestine for fermentation (thanks to bacteria and protozoa that produce enzymes to help further digest the plant fibre) and to release absorbable and usable forms of energy (the volatile fatty acids). Then it’s final part of the journey is colon to rectum and muck heap!


Your horses’ digestive tract is a delicate mix of bacterial and microbes which help ferment food. However, when sudden changes are made to routine or diet, they may result in colic, so it’s always crucial that changes should be done very gradually.


You may have heard your horses’ stomach being rather noisy, and this is generally good sign that the food is moving through the digestive system. However, being familiar with what sounds normal in your horse’s gut and spotting changes alongside other external physical changes should always form part of your routine stable management and care.


Maintaining horses on forage-based diets with minimal amounts of concentrates and avoiding abrupt changes in diet are critical factors involved in gastrointestinal health. When horses consume high levels of concentrates, some of the starch and sugar is fermented in the large intestine rather than digested in the stomach and small intestine. Unlike fibre that is fermented to produce Short Chain Fatty Acids (SCFAs) which the horse uses for energy, fermented starch and sugar from concentrates produce lactic acid. Remember that abnormal lactic acid production causes a shift in the population of microbes that make up the microbiome.


  • Make all feed changes slow. Seven days for hay/haylage and ten days for concentrate feed, this allows gut microbes to adjust.
  • Integrate new hay/haylage (even if it is the same type of hay) it probably has a different nutrient makeup which can throw your horse’s microbes out of kilt. When hay is changed abruptly, horses may get an increase in colic for about two weeks following the change.
  • Feed at consistent times of the day. If your feeding routine has to change, make the change slowly over several days.
  • Trickle feed roughage. Your horses’ gut evolution is made for eating this way.
  • Feed Aloeride aloe vera for horses Aloe vera is a fantastic anti-inflammatory and is excellent for supporting a healthy gut and digestion and is a natural, organic solution to holistic equine feeding.

For more in-depth revealing reading, an angle that you won’t readily read in horse magazines, go and enjoy Try Reverse To Make Your Horse Go Forward!

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