Pegasus News & Nutrition

Equine Gut Health - The Microbiome

The complexities of the equine microbiome, in relation to disease risk, inflammatory response and general health, is a growing area of research. As we discover more about the function of the equine digestive tract, it is becoming more and more apparent that looking after the equine microbiome, and encouraging diverse microbiota, is something not to be overlooked. Supporting a stable environment for gastrointestinal microbes is an important part of horse management, feeding management, and successful health and performance management.

It is important to remember that the entire equine gastro-intestinal tract (GIT) is colonised by a diverse community of micro-organisms, from the oral cavity through to the intestines. The different micro-organisms populating each area are known, collectively, as the microbiota, whilst the overall genetic material is known as the microbiome. The micro-organisms of the GIT play a role in natural health defence, feed digestion, absorption and synthesisation of nutrients for the horse. Alteration in the normal intestinal microbiome, known as dysbiosis, in association with impaired intestinal barrier function, is linked to several issues, including weight loss, behavioural changes, poor performance and chronic inflammatory responses.

Microbes in the GIT, most importantly the organisms populating the hindgut, are designed to function harmoniously, in an optimum environment, to facilitate effective digestion and feed passage. These micro-organisms, however, are sensitive to change. They can be affected not only by different feeds, but also by factors that we may not be as acutely aware of, such as stress, weather, temperature, disease, transport, time without feed, housing and, of course, dietary changes. In relation to dietary changes, when a horse’s feed is changed, the micro-flora also alters. This can take 4-7 days to occur, however a full digestive functional change may take weeks. Sudden or dramatic changes in diet can cause abrupt and significant alterations to the microbiome and result in digestive upsets.

In terms of GIT health, as horses are hindgut fermenters, roughage is digested by fibre fermenting bacteria (fibrolytic). Therefore, horses on a high fibre diet have plenty of this type of microbe in their large intestine. Starch and sugar, on the other hand, are digested in the small intestine using digestive enzymes. When starch and sugar spill over into the hindgut, a change in microbiota takes place. The starch and sugar are broken down in the hindgut by lactate-producing bacteria. The increase in lactate-producing bacteria, and increase in acidity of the environment, cause a change in the microbiota balance in the hindgut. The fibre fermenting bacteria find the environment unfavourable and begin to die off, resulting in an over population of lactate-producing bacteria, which further exacerbates the issue and reduces gut flora diversity. In severe cases, the intestinal lining is damaged, and the normal intestinal barrier becomes more permeable, allowing larger molecules and toxins to be released into the blood circulation. This is known as ‘leaky gut syndrome’ and can result in conditions such as laminitis.

To help manage and maintain healthy gut flora there are some risk factors to consider, such as diet, housing, exercise, travel and medications, for example, antibiotics. Ensuring your horse has access to adequate amounts of roughage, making dietary changes gradually, feeding small, regular meals are all tools to help avoid imbalances and alterations in the microbiome. Considering management tools for stress, travel, exercise and medications will also assist in ensuring your horse’s microbiome remains in a happy balance.

One of the best ways to ensure a balanced diet is by completing a diet analysis with a qualified nutrition advisor.

Sources:
Stewart AS, Pratt-Phillips S, Gonzalez LM. Alterations in Intestinal Permeability: The Role of the “Leaky Gut” in Health and Disease. J Equine Vet Sci. 2017 May;52:10-22. doi: 10.1016/j.jevs.2017.02.009. Epub 2017 Mar 7. PMID: 31000910; PMCID: PMC6467570.
Kauter, A., Epping, L., Semmler, T. et al. The gut microbiome of horses: current research on equine enteral microbiota and future perspectives. anim microbiome 1, 14 (2019). https://doi.org/10.1186/s42523-019-0013-3

Article by Pegasus Feeds, 27.05.2023

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