All About Digestive Enhancers

What Are They and Does My Horse Need One?

Horses are reliant on a large population of bacteria and other microorganisms, in the hindgut, which ferment the fibre in their diet to release energy and other nutrients that the horse can use. Collectively known as the ‘microbiome’, the health and balance of these microorganisms is key not only to the host horse’s digestive efficiency, but its overall health too, since some species produce valuable B vitamins and others are involved in the immune response.

Ensuring the horse’s diet is fibre-based is therefore important for a healthy microbiome but, if things get out of balance, additional help may be needed and that’s when gut supplements or ‘digestive enhancers’ can be useful.

What are Digestive Enhancers?

Digestive enhancers include prebiotics, probiotics and postbiotics, which all have slightly different functions.

Probiotics

Probiotics for humans contain live bacteria and aim to flood the gut with beneficial species, which can then stop the harmful species from becoming established – a process termed “competitive exclusion”. However there are no bacterial species authorised for use in feeds or supplements for horses so the term "probiotic" is used to refer to live yeast cultures. Because they require oxygen in order to live and, as the horse’s hind gut is largely anaerobic (free from oxygen), they need to be supplied in the diet on a continuous basis for the benefits to be effective.

Lots of research has been devoted to investigating the benefits of yeast and studies suggest that the addition of yeast to the diet results in increased numbers of beneficial bacteria and more efficient fibre digestion. Yeast may also provide the fibre-digesting bacteria with important nutrients, or co-factors, that stimulate their activity and may even bring the bacteria and the food particle together to make the digestion process more efficient.

The length of time probiotics are used for depends on the reason for their use. They can be used as a shorter term strategy in response to a more acute disruption to the microbial population, such as after a course of antibiotics. Alternatively, if the microbial population is likely to be compromised indefinitely, such as with old age, they may need to be used long term for ongoing digestive support.

Prebiotics

The definition of a prebiotic is “a non-digestible food ingredient that beneficially affects the host by stimulating the growth and/or activity of one or a limited number of bacteria in the colon”. In simple terms, this means that the horse or other host animal cannot utilise the prebiotic but it does have an effect on the bacteria in the gut. Prebiotics tend to be sugars called oligosaccharides, the most commonly used in horse feeds being fructo- and mannan- oligosaccharides, which have different modes of action.

To appreciate how prebiotics work we need to understand how bacteria maintain their populations in the gut. Bacteria have hair-like appendages that are able to recognise and attach to special binding sites in the gut wall where they reproduce; a process which requires a readily available source of food. If the gut lining is damaged then the opportunities for the bacteria to attach and reproduce are reduced so the overall population is compromised.

Mannan-oligosaccharides (MOS) are derived from the surface of yeast cells and provide a binding site for certain harmful bacteria. The presence of MOS in the gut therefore stops harmful bacteria attaching to the oligosaccharides in the gut wall thus preventing them from becoming established in the gut. Because attachment is species-specific, not all harmful species are trapped by MOS; Clostridia for example, which are known to be a cause of diarrhoea in horses, are not bound by MOS.

Fructo-oligosaccharides (FOS) are found and derived from various different sources including artichokes, chicory, onions and sugar beet and are the active ingredient in Digest Plus prebiotic. They are, quite simply, a food source for certain beneficial bacteria which they need in order to reproduce. Research has shown that harmful bacteria such as E. coli and Clostridium perfringens, cannot utilise FOS which means that beneficial species are able to competitively exclude them. FOS seems to be particularly useful when horses are suffering with diarrhoea, presumably because numbers of C. perfringens are reduced.

Postbiotics

These are a relatively new addition to the digestive support armoury. They are defined as inanimate microorganisms and/or the end products of microbial fermentation, like metabolites, that confer a health benefit on the host. The natural microbial population of the horse’s gut are continually producing these metabolites, which include the volatile fatty acids from fibre, that the horse uses as an energy source. They also include B vitamins and other compounds, which are beneficial to health and well-being, and which the horse’s microbiome should be producing at appropriate levels consistently.

When a horse is stressed or ill, the efficiency with which the microbes can produce the metabolites is reduced so, for example, feeding prebiotics will help improve the situation by providing fuel for the good microbes to produce metabolites. This means the ability of the microbes to produce metabolites is less impacted by stress, but it will still be impacted, particularly if it is large or sustained stress. The same situation applies if you feed live probiotic yeast; it will improve the gut microbiome’s resistance to the impact of stress, but it will still be impacted.

Postbiotics are produced by fermenting live yeast on a consistent medium in a very controlled environment. The yeast produces hundreds of metabolites, is then inactivated and the resultant product is a blend of the metabolites, cell wall fragments and other beneficial components. Feeding postbiotics daily, provides a constant level of metabolites directly to the horse, which is not affected by any stress the horse is subject to at the time. This helps support health, well-being, and any necessary recovery from stress or illness, effectively “taking the pressure” off the horse’s microbiome and allowing it to become reestablished at healthier levels.

When Might My Horse Need Digestive Enhancers?

There are times when it is obvious that the gut is not healthy and this is when digestive enhancers have the greatest potential to be of benefit. Diarrhoea, colic or really watery or foul smelling droppings are good indications that all is not well in the horse’s digestive tract, although some symptoms are not necessarily as obvious. Many people, for example, would not make the association that an underweight horse may have a compromised bacterial population. A digestive enhancer is therefore usually a good idea for all underweight horses, whether they’re the sort that stress and get a bit loose when they go to a show, or even severely undernourished individuals.

An increased rate of passage of food through the digestive tract means that bacteria are carried out quicker than they can maintain their numbers. Horses that get stressed or excited when they compete or travel often go to the loo much more frequently and may get very loose droppings as well. These individuals are also usually the ones that come back from a show all tucked-up. Digestive enhancers are often able to help stop this happening.

Bacteria are alive and, just like any other living organism, they need a food supply. If the horse has been starved then it is likely that the friendly bacteria will have been too, which allows harmful species to take advantage. This can lead to an unhealthy gut which can often mean that a horse won’t put on weight whatever he is fed.

Benefits to the Young and the Old

Diarrhoea is a serious problem for any horse but it is even more of a threat to foals who can become dehydrated and die within hours. Anecdotal reports suggest that FOS prebiotics are especially beneficial for clearing up diarrhoea and have worked particularly well in foals. It is important to stress that if a foal has diarrhoea, veterinary advice should always be sought immediately and prebiotics should not be considered as alternatives to veterinary medicines but rather as complementary to them.

The importance of certain species of bacteria is becomingly increasingly understood as links between health and nutrition are investigated in various species including humans and farm animals. Research has shown that numbers of Bifidobacteria decrease in old age as a result of diminishing secretion of gastro-intestinal fluids. This decrease has been implicated in reductions in immunity and the onset of age-related diseases which include cancers and arthritis in humans. Obviously it is too early to say whether these associations apply to the horse but indications are that helping to maintain levels of important beneficial bacteria such as Bifidobacteria, helps to maintain the overall health of the host animal.

In Sickness…

If a horse is injured or suddenly becomes ill they are frequently confined to the stable on box rest. This often necessitates a change of diet and they may also require antibiotics, all of which makes them vulnerable to digestive upsets. Using a digestive enhancer is one way of trying to combat the stress that this scenario loads on both the horse and the microbial population in the digestive tract.

Nutrition-related laminitis is another situation that results in a disruption of the bacterial population and so it makes sense that after an episode of laminitis, attempts should be made to restore the bacterial population. Digestive enhancers are not going to treat the disease but they might just help reduce the risk of further problems, such as colic.

...and in Health!

Your horse doesn’t have to be sick to use a digestive enhancer and many manufacturers include them, at maintenance levels, in a wide range of feeds, as a means of supporting a healthy gut microbiome and therefore a healthy horse, however, if a horse has any of the issues outlined above, the addition of a specialist supplement is likely to be beneficial.

New Better Biome contains pre-, pro- and postbiotics to provide a unique triple support package for the hindgut microbiome. It combines Digest Plus prebiotic with live probiotic yeast to support and stimulate the beneficial gut microbes, while postbiotics act as a back up to those produced by the microbiome.