Prebiotics and Probiotics

Horses and ponies have evolved to eat a high fibre diet but they do not have the enzymes needed to break down fibre into nutrients that they can use. Instead, horses rely on a population of micro-organisms in their hind-gut, which includes bacteria as well as fungi (e.g. yeasts) to break down the fibrous plants that they eat.

As well as helping horses to gain energy from their fibre-rich diet, the micro-organisms produce vitamins (such as biotin), help to maintain gut movement and act as a barrier against harmful bacteria. The micro-organisms found in the horse’s hindgut play an important part in the overall well-being of the horse. They live in a delicate balance and can be disrupted by a number of factors which include; stress (for example, when a horse is travelling or at weaning), medication (such as worming treatments and antibiotics) and when there are sudden changes in the diet.

Ensuring that your horse is provided with a high fibre diet will help to support the microbial population of the gut. Reducing stress and making any changes to the diet slowly (ideally allowing 7 to 10 days) will also help to keep the gut flora in balance.

The use of prebiotics and probiotics has become popular in recent years so what are they and how can they benefit your horse?

Prebiotics and probiotics – What is the difference?

Both prebiotics and probiotics help to keep the gut healthy but work in different ways;


A prebiotic is a non-digestible feed ingredient that limits the number of harmful microbes or improves the digestive environment for beneficial microbes. In horse feed there a two types, which are commonly used – Mannan-oligosaccharides (MOS) and fructo-oligosaccharides (FOS).

MOS are non-digestible sugars that originate from yeasts. They are beneficial for the horse because they reduce the risk of harmful bacteria (such as Salmonella and E. coli) causing disease. Rather than allowing the bad bacteria to attach to the gut wall, the MOS acts as a sticky sponge, clearing up the harmful bacteria and removing them from the digestive system.

FOS works by providing the beneficial microbes in the horse’s gut with a source of energy, allowing them to reproduce and increase their population, which results in less opportunity for bad bacteria to thrive.

There are also a number of fibrous ingredients such as unmolassed sugar beet and chicory, which are used in horse feeds that can have a prebiotic effect in the gut.


A probiotic is a live bacteria or yeast that ‘tops up’ the population of beneficial microbes in your horse’s gut. The use of probiotics often causes debate because there are a limited number of studies that have been conducted into their effectiveness.

In horse feeds and supplements, live yeast is commonly used as a probiotic because it is still viable after processing and on reaching the hindgut. There are a number of potential benefits from adding a probiotic to a horse’s feed. Increasing the number of beneficial microbes mean there is less scope for harmful bacteria numbers to increase. Live yeast can also help maintain the hindgut’s optimum conditions for the existing microbial population which increases their efficiency for fibre digestion.

Our Barley & Molasses Free Range has been carefully formulated to ensure the feeds have low starch and sugar levels and contain high quality fibre ingredients. The feeds also contain prebiotics or a combination of prebiotics and probiotics to keep the digestive system healthy.