• Quality Assured
  • Quality Assured

The Foal's Microbiome

Setting up a foal for life


There’s an often completely ignored, yet very important consideration when it comes to raising a foal in its first few months, and that’s about creating its microbiome. How a foal’s microbiome is established will basically determine its health – or unhealth – for the rest of its life.

That first year of the foal is crucial, and very much depends on how the mother was fed, because a foal eats its mother’s faeces to build its own microbiome – a process known as coprophagia.

We now know that if the dam has a disturbed microbiome, the foal will end up with the same poor-quality microbiome. New breeding practices are now putting mares with disturbed hindgut function in with other mares known to have a healthy microbiome, so the foal will eat mixed faeces to give its own hindgut a better chance for good microbe colonisation.

Otherwise, if the foal is unable to establish a healthy microbiome, you have a metabolic-risk patient for life, because if a healthy microbiome isn’t there to start with, it’s very difficult to restore and recreate.

It all starts with the hindgut

Doesn’t everything! In a grown horse, the hindgut – the large intestine, and specifically the cecum, is a huge fermentation vat full of micro-organisms - bacteria/fungi/protozoa et al - which digest (ferment) plant fibres.

Once the eaten grasses/barks/leaves/berries and woody forage/roughage has been ground down by the teeth, then made its way through the stomach, the small intestine and finally to the large intestine, these microbes now mix with the digesta and start degrading/fermenting the plant fibres into their nutrient components – firstly, the horse’s main energy source is produced via three volatile fatty acids – butyrate, proprionate and acetate, plus several amino acids, vit.K, and two B-vitamins, B12 and B6 in a specific ‘activated’ form – this activated B6 is critical for healthy liver and kidney function - https://equinatural.co.uk/i/kpu-cryptopyrrolura

Of course the microbes need to get there first – when a foal is born the gut is still sterile, so now microbes need to get to the hindgut – hence coprophagia. As the foal develops they start to eat mum’s faeces and forage, in around a 50/50 split of each - 50% plant fibres, 50% mum’s microbes from her faeces, and so the foal builds the same microbiome as its mum.

This is how the gut microbiome is formed. A foal’s foregut isn’t too acidic yet, so the microbes can safely get to the hindgut without being disinfected away by the acid. Along the way through the small intestine they’re recognised by the new immune cells that acknowledge these are foal’s individually personalised microbiome microbes, and that’s basically it. They then stay for the foal’s entire life with the immune cells thereafter recognising - and swiftly dealing with - a microbe ‘invader’. It’s exactly the same as us humans where we’re nurtured from birth via our mother’s breast milk – our own microbiome is created identically from our own mother.

This process takes the foal around 4-5 months of regularly eating mum’s poo to create a stable microbiome in their gut system, and what builds their ability to finally wean off their mother’s milk to grass forage and roughage.

In nature this is really smart system because only a mare with a healthy microbiome is able to get enough energy from her feed to produce a foal – a mare with a poor microbiome mare will not create enough energy to produce a foal. Thus, a disturbed microbiome will die off with those mares, so evolution continues to create only strong foals which create a strong herd, which has a direct healthy relationship with the soil and landscape. Nature gets it right, but it can all go wrong when us humans get involved.

Where it all goes wrong

This coprophagia process during the first 4-5 months is crucial for the foal – disturb it, and we’re looking at lifelong digestive and metabolic problems. If a foal is given antibiotics, this disturbs the process of the microbes learning to live in the gut, exactly the same with us humans – it’s said that a gut microbiome never recovers after just one course of antibiotics. This also explains why foals that are weaned too early end up with multi-metabolic disorders in later life.

We get the same problems if we feed both mother and foal inappropriately – haylage is a huge culprit here because haylage is full of lactic-acid bacteria, which is one almighty pro-inflammatory, gut-damaging, pathogen microbe that we never want in the gut system. Why? Because it produces lactic-acid gas in the hindgut, which not only blows up and expands the intestines and tears the fragile membrane wall (leading to leaky gut), but it also lowers the pH value to sour, when the intestinal environment should always remain at neutral. Feed haylage, and you’ll instantly cue immediate hindgut microbiome dysbiosis/acidosis. All covered in our Gut System chapter.

If we feed haylage to a foal, the immune system then mistakenly accepts lactic-acid bacteria as normal, so it’s acknowledged as a resident for life. This will forever and thereafter affect the fibre digestion due to permanent dysbiosis in the hindgut, eternally disrupted with an overpopulation of pathogen microbes over the beneficial fibre-fermenting microbes. Why we should never feed haylage to horses is all covered on our website here: https://equinatural.co.uk/i/haylage-why-we-shouldn-t-feed-it – it’s fine for ruminants – cows, sheep, goats, who have a completely different four-chambered stomach and ferment fibre in their rumen, but absolutely not for the equine gut system which ferments fibre only in the large intestine.

We need to change our feeding practice to create a more hostile environment for the pathogen microbes, so the beneficial microbes can recolonise and outgrow the bad, to restore the microbiome - we do this by feeding hay, hay, and more hay. However, feed haylage to a foal and you’ll create the wrong microbes which will always outgrow the good guys. Sadly, this is now so widespread that we’re already seeing foals with metabolic problems, i.e. sweet itch being seen at age of 2, never mind so many young horses allergic to just about everything - all due to a damaged microbiome, thanks to a completely human-made problem.

The research

So, get the feed wrong and it creates unwelcome microbes in the gut microbiome which are passed on through the generations. For the last 20-30 years, most research has been focused on feeding the small intestine, because for scientists this is where the most interesting, complex digestion takes place – sugars, fats, proteins and carbs. Yet it's the hindgut which is where all the important action takes place, and research is only now, over the last 5-years or so, coming to realise that studies into the hindgut have been badly neglected. Healthy hindgut = healthy metabolism.

With all the human microbiome research intensifying over the last decade, i.e. on IBS, Crones, Celiac etc., it’s now known that the microbiome manipulates everything, literally every function in the body. Hence interest has thankfully now grown for the equine gut with early developments in research out there now and with the first publications coming out.

The realisation is that horses with significant metabolic disturbances have a disrupted microbiome, i.e. of course the EMS/IR/lami-prone horse, but also chronic colicing, diarrhea/faecal water, bloating/gas, multiple allergies triggering an autoimmune overreaction in the immune cells, even headshaking's been mentioned – all signs of dysbiosis in the hindgut. This can all be prevented by giving a foal the chance to colonise its cecum microbes from its gut-healthy mother, or a gut-healthy mare.

Prolonged diarrhea

🤓 Science-Alert! This may sound a little science-y but bear with me, because prolonged diarrhea in a foal can be seriously dangerous. This is all cellular-related, and where the salt:water connection is so important.

The body’s cells need a distinct pressure to function, reason being that unlike plant cells which have a solid wall, mammalian cells don’t – our cells have a permeable membrane wall around them, and in order to work, cells need the right water pressure inside each and every one of them, in their intracellular environment.

This is called osmotic pressure, and it’s regulated by salts and water. Thing is, water in the body doesn’t have a pump to move it around, so this is where salt comes in. Salt attracts - draws - water, so where salt goes, water follows, and this is all controlled by the kidneys doing clever stuff by naturally holding back or excreting salt and/or water where needed. (I'm getting too nerdy for my own good - I love this stuff 😉)

So, if a cell’s intelligence knows that it’s drying out and shrinking, it absorbs - takes up - salts from the extracellular environment (the fluid area outside the cell) and water follows. Equally, it can excrete salt for the water pressure to follow if it’s too full of water. The cell’s natural intelligence regulates its own osmotic balance, but there has to be enough salt and water available in the whole body, which is all regulated by those clever kidneys.

This balance breaks down if there’s prolonged diarrhea – same with dogs if they vomit for days on end, a typical sign of kidney issues. As the body dehydrates, urgent attention is needed with the salt:water regulation, which will now be significantly out of balance and causes the body to dehydrate further. Hence why diarrhea in young foals is so serious because their body is so small, so they dehydrate very quickly, thus it’s vital to add salt/electrolytes to the feed, and obviously monitor hydration.

To conclude

In that strange, perfect, parallel world that none of us live in, wouldn't life be so much easier if we could simply feed healthy, equine microbiome-appropriate, cellulose-digesting microbes to our horse when there’s a biome disturbance, to regenerate the microbiome and outgrow the bad guys – this way we’d be able to restore the natural microbiome that the equine gut system is evolved for.

But sadly, such a thing doesn’t exist. We now know the health risks of lactic-acid bacteria residing in the large intestine, and a recent publication courtesy of Dr Christina Fritz is now showing that yeasts may also negatively disturb the equine hindgut biome.

All equine probiotics out there either include lactic-acid bacteria or yeast, the science now up to date enough (2021) to show that neither of which are a recognised colony member of the equine microbiome. Ruminants, yes - yeast, which has been used for years as an equine probiotic, was originally designed for the ruminant's gut system; same for us humans too - our gut microbiomes positively thrive on lactic-acid bacteria - you can't buy a human probiotic without seeing lacto-somethingorother in the composition. But not for horses - it appears not for the equine microbiome.

Long and short, for those of us with horses experiencing never-ending multi-metabolic disorders (see our KPU page), if there’s any possible way to check the history of our horse back to birth, we’d have more of a clue as to how they were initially fed/raised/weaned, and that hopefully no antibiotics or haylage were fed in the first 6-months of their life, or that the mother unknowingly already had hindgut dysbiosis.

PS – food for thought. This is also all connected to why there are so many issues with importing horses from one continent to another, i.e. bring a horse from Iceland to Spain and their digestion falls apart because they’re now on completely different forage/roughage. Bring a horse from Spain to the UK and watch major metabolic disturbances occur as they chow down on our neon-green grass-blade-and-no-fibre forage instead of their dry, stemmy grasslands and hay diets. All because their microbiome is only matched to their native forage on which their microbiome was made.

The good news for these horses is that with each generation they gradually better adapt. But not such good news for the original horses.