The Fundamentals of Equine Nutrition

Horses are non-ruminant herbivores with a digestive system designed for continuous, low-volume grazing. Unlike cattle, they have a relatively small stomach but a large hindgut (caecum and large colon) where fermentation of fibre takes place. This means horses are built to eat small amounts frequently — not large meals twice a day as is often the case in domestic management.

Understanding this simple biological fact is the starting point for good feeding practice. Many common health problems in horses — including colic, gastric ulcers, and laminitis — are linked, directly or indirectly, to management practices that go against the horse's natural digestive design.

The Golden Rules of Horse Feeding

  1. Forage first – The majority of a horse's diet should be forage (grass, hay, or haylage). Aim for a minimum of 1.5–2% of body weight per day in forage dry matter.
  2. Feed little and often – Never allow a horse to go more than 4–6 hours without access to forage. A stomach that remains empty for extended periods is at high risk of developing gastric ulcers.
  3. Make changes gradually – Any change in diet — a new batch of hay, introducing hard feed, changing pasture — should be made over 7–14 days to allow the hindgut microbiome to adapt.
  4. Feed by weight, not volume – Scoops are not a reliable measure. Weigh your feeds until you know exactly what you're giving.
  5. Always provide fresh, clean water – A horse at rest may drink 20–30 litres per day; a horse in hard work in hot weather may need twice that.

The Components of a Horse's Diet

Forage

Grass, hay, and haylage are the cornerstone of the equine diet. Good-quality grass pasture can meet many of a horse's nutritional requirements in spring and summer. Hay provides fibre and keeps the gut moving during periods of reduced grazing. Haylage (fermented hay) has a higher moisture content and is often higher in energy and protein — useful for hard-working horses or those who struggle to hold weight.

Concentrates (Hard Feed)

Concentrates — including cereals, compound feeds, and mixes — add energy, protein, vitamins, and minerals above what forage provides. Not every horse needs hard feed: a good doer in light work on quality grazing may do perfectly well on forage alone, supplemented with a balancer to ensure micronutrient needs are met.

Horses in regular, harder work (competitions, eventing, endurance) will typically require some concentrate feed to meet their energy requirements. The type and quantity will depend on the individual horse's metabolism, workload, and condition score.

Balancers

A balancer is a concentrated pellet fed in small amounts (typically 100–500g per day) that provides vitamins, minerals, and amino acids without significant calories. They are ideal for good doers, horses on hay-based diets, and youngstock who need nutritional support without excess energy.

Supplements

The equine supplement market is vast, but most horses on a well-balanced diet do not need extensive supplementation. Common supplements include:

  • Salt/electrolytes – especially important for horses in hard work or hot conditions
  • Joint supplements – glucosamine, chondroitin, and MSM are widely used in older or performance horses
  • Digestive aids – pre- and probiotics, and gut-support products for horses prone to loose droppings or ulcers
  • Biotin – commonly fed to horses with poor hoof quality

Assessing Your Horse's Condition

Body condition scoring (BCS) is a systematic way of assessing your horse's weight and fat coverage. In the UK, the Henneke 9-point scale and the Carroll & Huntington 0–5 scale are commonly used. You should be able to feel your horse's ribs with light pressure but not see them clearly. A horse that is too fat carries health risks (laminitis, metabolic disease); one that is too thin is likely not receiving enough energy for its workload.

Condition-score your horse regularly — at least once a month — and adjust the diet accordingly. A weigh tape is a useful and inexpensive tool for monitoring weight over time.

When to Involve a Nutritionist

For horses with specific health conditions — equine metabolic syndrome, Cushing's disease, gastric ulcers, tying-up, or extreme weight issues — consulting a qualified equine nutritionist or your veterinarian is strongly recommended. Getting the diet right for a horse with a health condition can make a dramatic difference to their quality of life and performance.