Hesteklinikken og hestetannklinikken på Forus travbane
Hesteklinikken og hestetannklinikken på Forus travbane


PREBIOTICS – The new digestive aid

Prebiotics are the latest addition to the range of supplements available that are designed to enhance gut function and help promote good health. If you’ve been wondering how they work or when you might need to use one then read on, this article should answer all your questions.

The Microbial Population

The horse has a resident population of micro-organisms in the digestive tract including bacteria, fungi and protozoa. The exact number of different types of bacteria present in the horse’s digestive system has not been established but it is known that beneficial species are responsible for breaking down fibre, producing B vitamins and are an integral part of the immune system. Pathogenic or “bad” bacteria such as E. Coli and Cl. Perfringens, can result in diarrhoea, colic and other digestive upsets.

Beneficial bacteria have a pretty tough time maintaining their population in the hind gut. The continuous movement of food through the digestive system carries bacteria out and they are also in competition with other species for food and places to live. If the rate of passage of food increases significantly or the environment in the hind gut changes to become more hospitable to pathogenic bacteria, the numbers of beneficial bacteria can decline resulting in compromised digestion and poor health and condition.

What are Prebiotics?

Prebiotics differ from probiotics in that they do not contain live bacteria but instead “act” on bacteria. There are two main products used in horse feeds and supplements that are classified as prebiotics. Fructo-oligosaccharides or FOS provide a food source that only beneficial species of bacteria, such as bifidobacteria, can utilise. FOS are naturally occurring in foods including onions, garlic and artichokes but are mainly derived from chicory or sugar beet when used for horses.

The other type of prebiotic is mannan-oligosaccharides, which is usually referred to as Bio-MOS and is derived from the outer wall of yeast. It agglutinates or binds to pathogenic bacteria so that they cannot become attached and established in the host animal. Bio-MOS is different to yeast culture which has a stimulatory effect on cellulose or fibre digesting bacteria.

So when should you use a prebiotic?

There are a number of different situations and circumstances where using a prebiotic can be beneficial. Giving foals a head start

Research into human nutrition has found that breast fed babies have greater numbers of bifidobacteria in their digestive tracts. Researchers suggest that as bifidobacteria have an important role in immune function, this could be the reason breast fed babies tend do better than those fed milk replacers and artificial foods, as they are equipped to resist infection and disease which allows normal growth and development to occur.

Foals quite commonly suffer with diarrhoea and so as a preventative measure, prebiotics can be given to the mare and/or the foal to try and reduce the incidence of digestive upsets. However, as foals can become seriously ill very quickly, it is vital to call a Vet if there are any signs of ill health.

The effects of old age

Just as for humans, advances in medicine and healthcare mean that horses are living longer. Older horses often suffer with loose droppings and are more prone to colic. They are also often given antibiotics to fight infections, all of which can disrupt the bacterial population in the digestive system. It has also been found that changes in the composition of secretions in the digestive system can result in a reduction in numbers of bifidobacteria. Using a prebiotic will help to increase the numbers of beneficial bacteria thereby helping to counteract some of the effects of old age.


The digestive system can be stressed for a variety of reasons, many of which are obvious such as travelling and competing. Simply stabling a horse for long periods, such as for box rest after an injury, can also be detrimental. Stress generally leads to an increase in the rate of passage of food which is frequently evident in competition horses when their droppings become very loose. In these situations feeding a prebiotic should help to restore a healthy population of bacteria.


Diet has a huge influence on the bacterial population present in the digestive system. As certain species are required to digest specific foods a sudden change of diet should be avoided which is most important when changing from a very high fibre diet to a very high concentrate diet or vice versa, as opposed to just changing from one type of concentrate to another. Adding a prebiotic to the feed when changing the diet will ease the transition and help to avoid digestive upsets.

Although prebiotics are not a replacement for medicines, they offer a means of trying to promote good health and avoiding disease. It is likely that they will receive even greater recognition in the future as research continues to find benefits to both human and animal health.

Baileys produce a prebiotic powder supplement called Digest Plus. For more information, click on * Digest Plus * on the top right drop down bar.

By Katie Lugsden BSc (Hons) Equine Nutritionist