The Microbiome - what is it and why is it important for horses?
What is the Microbiome?
At birth, the gastrointestinal tract of mammals is sterile, with no micro-organisms present. In the months following birth it rapidly becomes colonised by a variety of protozoa, bacteria, viruses and fungi. These organisms vary according to the environment and the diet of the young animal, but during the first year of life become established in a pattern that in health, may vary very little until old age.
This collection of microorganisms is known as the microbiome. It is very complex, with for example, over 500 species and strains of bacteria alone, and a total of over a trillion organisms. There are more bacterial cells in the human microbiome than there are human cells in the whole body.
Where does the microbiome live?
These organisms, of course, are not pathogenic and come to survive happily without any attack from the host’s immune system. They live on food residues passing down the gut, and also other substances found in the intestinal stream such as mucus and dying cells shed from the bowel lining. The large intestine (colon) contains very little oxygen and so the great majority of bacteria found there are anaerobes, which do not thrive in the presence of oxygen..
The Microbiome plays an important part in the wellbeing of animals
It was thought for many years that the microbiome was merely a collection of microorganisms which were ‘passengers’ in the colon with little physiological importance. This view is now known to be mistaken. In health they may digest fibrous food residues to release energy, produce vitamins, break down toxins and carcinogens and help defend the host from infection. More recently it has become apparent that they may also be a factor leading to chronic disease.
Our knowledge of the Microbiome is increasing.
The study of the microbiome has not been easy because of the difficulties in identifying the organisms present. The classical technique is to culture bacteria isolated from the stools in the laboratory, but they are often very fastidious and it may be very difficult to reproduce the correct conditions in the laboratory for them to be grown successfully. Dead organisms cannot be cultured. A more reliable method is by the identification of microbial nucleic acids but this can only demonstrate those whose structure is already understood and it is likely that such techniques miss many microorganisms which are still unknown.
A more sensitive method of assessing bacterial activity is the study of chemicals produced by the microbiome. These are detectable in both stool and after absorption into the bloodstream and excretion through the kidneys, in the urine. There are many hundreds of such metabolites but these can be separated and identified by mass spectrometry and their relative significance determined using complex computer programs. This technique is known as metabolomics and in this way we have demonstrated that the microbiome is abnormal in diseases which are not obviously related to bacterial activity such as food intolerance, bowel cancer and autoimmune conditions such as immune thrombocytopaenic purpura.(ITP).
Understanding the Microbiome is key to better understanding health in animals...
It seems likely therefore that the microbiome will be shown to be important in our understanding of a range of equine diseases which are poorly understood, such as laminitis and colic. There is now great interest in manipulating the organisms it contains, in the hope of promoting health and treating disease. This is not easy as the microbiome is generally very stable, because of a phenomenon called ‘colonisation resistance’. Put simply this reduces the chance of infection. Organisms entering the colon must compete for nutrients with those already present, which also produce chemicals called bacteriocins to kill off invaders. On top of this the animal’s immune system recognises extraneous bacteria and attacks them vigorously.
...as well as in Humans
Diet has been demonstrated to be effective in changing the metabolome in human disorders such as Crohn’s disease, by changing the nutrients available for bacterial growth, but must be continued long term for success. Diets are both inconvenient and unpopular. . Attempts have therefore been made to improve the microbiome directly. Transplants of healthy faeces from other individuals are rarely successful. Apart from their inherent distastefulness they also carry the risk of cross-infection. Administration of harmless bacteria (probiotics) or nutrients which will promote their growth such as oligofructose (prebiotics) have been widely tried with again disappointing results. Probiotic bacteria appearing in the colon are attacked in exactly the same way as pathogens and disappear rapidly from the faeces, and prebiotics are just as likely to promote the growth of harmful bacteria as of those which are believed to be desirable.
EquiNectar represents a completely new approach to managing gut health in horses.
Enzyme rich malt extract (EquiNectar) represents a completely new practicable way of manipulating the microbiome successfully. Equines, which rely for their energy mainly on bacterial breakdown of fibrous foods such as grass and hay in the colon eat little starch in the wild and have evolved possessing low levels of the enzymes necessary for its digestion. Excess starch in the diet may result in undigested starch reaching the colon, producing toxins, metabolic syndrome, laminitis and colic. The high levels of starch digesting enzymes produced by germinating barley may be extracted, and when fed to horses or man, will increase intestinal digestion and so reduce the quantity of starch reaching the colon. This change in the supply of such an important nutrient has been demonstrated significantly to improve the microbiome in horses, with corresponding benefits in health, condition and performance.
EquiNectar is the first practical and harmless product to offer reliable control of the microbiome and will have a vital role to play in both equine and human health.