Reminder, and forgive me for repeating myself - a horse is nothing more, and nothing less, than a hindgut grass-forage fibre-fermenting machine.

And the only place to get the appropriate fibre for the equine hindgut? Long grass stems - this is where the cellulose fibre sits, in the stems of long, grown grasses, not to short neon-green grass leaf that hasn't had a chance to grow a stem. Which means ...

In the perfect world, it should be hay only, 24/7, 365-days/year. Yikes! Trust me, I hear you - Hay Only?! But trust me again - there are some very good reasons why it should only ever be be hay.

Fifty-plus years ago, before intensive farming practices began, our UK soils were healthy and nutrient-rich, and our grasslands that grew in these soils were healthy and nutrient-rich as a result. A horse grazing in a typical UK paddock back then would have had the choice of approximately 30-40 different plants and lovely, long, fibre-filled stemmy grasses growing long and allowed to go to seed (no-one 'topped' back then). Each species brought its own specific nutrients and lots of lovely prebiotics to nourish the gut microbes, at the same time containing natural sources of digestive enzymes and naturally occurring, beneficial bacteria essential for a balanced diet.

These days, because of intensive farming, selective seeding, chemical fertiliser spraying etc etc., the grazing is limited to sometimes as few as four varieties of grasses if we're lucky, never mind our soils now so acidic and drained of any minerals that only buttercups thrive.

Also, by the very nature of today's livery yards, horses are rarely kept as a loose herd, more often individually isolated in designated, small paddocks, so what grass they have is usually over-grazed, and sick.

But - it's a much Bigger Picture than this. Yes a horse is meant to eat 'grass', but as mentioned above, we're talking long, stemmy, fibrous, woody roughage - not our short, vivid neon-green UK leaf grass which is eaten down before it gets a chance to grow its stem and produce the seed head. Our typical paddock grasses contain no fibre because that vital fibre is in the long stems, and our paddock grasses barely have the chance to grow longer than the first leaf.

Short grass is growing grass, a regular plant trying to grow its seed so it can regenerate; that growing leaf is sapping as much sunlight as it can to synthesize its growth chemicals - pectins, an essential part of the plant growth development (cell wall expansion), along with our old favourites sucrose and fructose, aka yummy sugars - so it can Grow! Except our horses eat what they can get before the grass blade has had a chance to fulfill its life cycle.

Thing is, one of the bad, and very pro-inflammatory microbes in the microbiome - lactic acid bacteria (LA) - just loves pectins, and if pectins come sailing on through into the GI tract, they chow down on them and create lactic acid, which lowers the pH value and makes the GI tract acidic. Cue very uncomfortable gas in the small intestine - a place where no gas should be - and hindgut acidosis, now so prevalent that it's being considered an epidemic. We cover more on LA bacteria in the Haylage - why we shouldn't feed it page.

Apart from the obvious, why else is fibre so important?

As well as providing food for the healthy hindgut bacteria to create the horse's energy, soluble fibre helps lower cholesterol, blood sugar and insulin, balances hormone levels, removes excess estrogen, makes vitamins and minerals, provides food for the colon cells, and more.

FIbre slows the rate at which food enters the bloodstream, and increases the speed at which food waste exits the body though the GI tract. This keeps blood sugar and cholesterol in an ideal balance, eliminates toxins from the gut, and slows down appetite.

A quick word on bran - bran (wheat fibre) is mostly insoluble and doesn’t get digested - think of it more as an intestina; scouring pad. Plus it comes from wheat, and that's a whole other story - see our separate chapter, 'Wheat, the beginning of today's disease culture'.

⁣Roughage

We also need to remember the roughage factor - that crucial fibre resides in the coarse, roughage stems of long grass, and in order to get at the fibre, it needs to be chewed properly to expose the inner fibre of the stems, along with bushes, twigs and branches which give them their lignan (woody) fibres. This keeps our horses occupied all day as they have to break down the fibres by grinding them left-to-right with their back molars. Chewing itself has many benefits apart from evening tooth wear - it releases endorphins (happy reward hormones), and produces saliva which contains the first digestive enzyme (amylase, the starch digester), as well as bicarb which buffers foregut acidity.

It's a no-brainer - long, coarse, stemmy grass, and preferably meadow grass for the grass diversity, then dried to hay, is the most species-appropriate forage fibre to feed a horse. With a horse being a hindgut fibre fermenter, we need to get those all-important fibres - cellulose and hemicellulose - into the hindgut to nourish the friendly biome microbes to do their job and give our horse its energy. The perfect cut is a late-only cut where the grass has flourished enough to seed, so there’s lots of woody stem.

The horse's own self-produced nutrient profile also depends on fibre as well, as many essential nutrients are produced by the biome, including the B-vits, vit.K, vit.C, and many amino acids.

Basically it all starts in the mouth and the chewing process, for a minimum of 18-plus hrs/day, where the forage is ground down into a ‘hay roll’ which exposes all the inner fibre. If you really want to get anal about it, in the perfect world the hay strand ideally needs to be 8cm or longer, or less than 5mm for our dentally-challenged horses for easy swallowing. If it's in between this the science says it won't be chewed/ground enough to expose the fibre and won’t create a hay roll, which means fibres will then sit in the hind gut for longer and ferment.

For the full story of how a horse eats, head to our Gut System page.

Energy levels in hay

Here's the good news - hay provides awesome energy levels! A horse needs around 2% of their bodyweight in total forage per day, so if a horse is kept off our UK grass and fed a hay-only diet (the perfect world), for the average 500-600kg horse we're talking 2-3kg hay/100kg bodyweight, so a total of around 10-12kg/day.

So to energy, and a 500-600kg horse needs around 80mj energy/day. Hay provides around 8mj/kg, so that 10-12kg hay/day will provide 96mj energy.

Now let's put that in real terms. Let's say a horse is ridden for 1-hour in what's termed 'light' work, i.e. 20-mins trot, 15-mins canter, the rest at walk. This work alone would utilise just 8-12mj of energy, so you can see there's plenty of energy in a hay forage diet 😉