Dr Pat Harris, Director of Science here at SPILLERS, gave a lecture on digestive health at the Horses Inside Out Conference in Leicestershire. Pat’s talk focused on how a better understanding of the horse digestive system can help to maintain health and performance, as well as reduce the risk of conditions such as colic and gastric ulcers. With this being such an important topic, we wanted to share some of the key takeaway messages with you.

To benefit the horse digestive system - Feed as much forage as possible

One thing to understand about the horse digestive system is that it is built for forage. Horses evolved to spend 16-18 hours per day grazing so it’s no surprise that feeding sufficient forage has a number of health and behavioral benefits.

  • Ideally, forage should be provided ad lib wherever possible although this may not be practical if you’re watching your horse’s waistline.
  • In most cases total intake should not be restricted to less than 15g per kilogram of bodyweight per day (dry matter). On average this equates to approximately 9kg of hay or 10-12kg of haylage for a 500kg horse without grazing

Look after your horse’s teeth

Effective chewing helps to achieve optimal digestion, in addition to producing up to 35-40 litres of saliva a day which acts as a lubricant and an important buffer for stomach acid.

  • Horses that are unable to chew properly or bolt their feed are at greater risk of conditions such as colic and choke. They are also less likely to utilise their feed efficiently.
  • Horses produce saliva in response to chewing – another reason to feed as much forage as possible and add chopped fibre to meals!

Did you know?

The average 500 kg horse will chew around 3,500 times per kilogram of hay consumed taking about 40 minutes, compared to just 850 times per kilogram of oats (approximately) taking around 10 minutes!

Feed small meals

Another key factor to consider with the horse digestive system is feeding small meals. Large meals increase the rate of stomach emptying and in turn, the speed at which food passes through the small intestine, limiting digestive capacity. Feed no more than:

  • 2kg per meal (dry weight) in total for horses 500kg and over
  • 400g per 100kg of bodyweight per meal for ponies i.e. 800g per meal for a 200kg pony


Make all changes in diet slowly!

Any changes in diet can affect the microbial population of the gut.

  • Changes in forage can be a greater risk factor for diarrhoea and colic than changes in ‘hard feed’
  • Small changes can be made gradually over 3-5 days
  • More significant changes should be made over minimum period of 2-3 weeks

SPILLERS’ Tip: replace no more than 500g of existing feed for 500g of new feed every other day (for horses, less for ponies)


Gastric Ulcers

  • The horse digestive system produces acid continuously (at varying rates) throughout the day increasing the risk of gastric ulcers, particularly in horses on low forage diets.
  • Acid suppressants such as Omeprazole have no long term effect and if other changes are not implemented, ulcers can return to their pre-treatment state within 30 days after treatment.
  • Research has confirmed that changes in feed can reduce the occurrence of gastric ulcers following Omeprazole treatment, even if other changes in management are not possible.

For more advice on supporting digestive health contact the SPILLERS Care-Line