Okay, so to the perfect world, and it's 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 be hay only.
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 grass. For starters, 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. Which means it's too green - short grass is growing grass, a normal plant trying to grow to seed so it can regenerate, so that growing leaf is sapping as much sunlight as it can to synthesize nutrients - yummy sugars - so it can Grow! Except our horses eat what they can get before the grass blade has a chance to fulfill its life cycle. Which means that grass blade is full of pectins (aka sugars!), which are an essential part of the plant growth development (cell wall expansion).
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.
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 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 nutrient profile depends on this type of hay as well, as many essential nutrients are produced by the biome, including the B-vits 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. 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 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 😉