Horse feeding is one of the most important aspects of horse ownership — and one of the easiest to get wrong. Horses have a unique digestive system evolved for near-constant grazing on fibrous forage, and getting the balance right between forage, hard feed, and supplements is essential for maintaining health, condition, and performance.
Whether you’re a first-time horse owner or an experienced equestrian looking to refine your feeding approach, this guide covers the fundamentals of horse nutrition, common mistakes to avoid, and how to tailor your horse’s diet to its individual needs.
Table of Contents
How the Horse’s Digestive System Works
Understanding the equine digestive system is the key to feeding horses correctly. The horse is a hindgut fermenter — meaning the bulk of its fibre digestion takes place in the caecum and large colon, rather than in the stomach.
The Foregut
The horse’s stomach is remarkably small relative to its body size, holding only around 8–15 litres (roughly the size of a rugby ball). It is designed for a continuous trickle of food, not large meals. The stomach produces acid constantly — unlike humans, whose acid production is triggered by eating — which means an empty stomach is vulnerable to gastric ulcers.
From the stomach, food passes into the small intestine, where simple sugars, starches, proteins, fats, and some minerals and vitamins are absorbed. Feed that is high in starch (such as cereal grains) is primarily digested here.
The Hindgut
The hindgut — comprising the caecum, large colon, and small colon — is where fibre fermentation occurs. Billions of beneficial microorganisms break down structural carbohydrates (cellulose and hemicellulose) from forage, producing volatile fatty acids (VFAs) that serve as the horse’s primary energy source.
This microbial population is finely balanced and sensitive to sudden dietary changes. Rapid shifts in feed type — particularly increases in starch or sugar — can cause the wrong bacteria to proliferate, leading to hindgut acidosis, colic, or laminitis.
Forage First: The Foundation of Every Horse’s Diet
The single most important principle in horse feeding is that forage should form the basis of every horse’s diet. As a general rule, a horse needs a minimum of 1.5% of its bodyweight in forage (dry matter) per day — ideally 2% or more.
For a 500 kg horse, that means at least 7.5 kg of hay or equivalent forage daily, with 10 kg being closer to ideal for most horses in light to moderate work.
Why Forage Matters
- Gut health: Forage keeps the hindgut microbiome stable and functioning correctly
- Ulcer prevention: Chewing produces saliva, which buffers stomach acid. A horse chewing hay produces roughly twice as much saliva as one eating concentrates.
- Behavioural health: Horses are designed to spend 16–18 hours a day eating. Restricting forage leads to boredom, stress, and stereotypic behaviours such as crib-biting and weaving.
- Thermoregulation: Fibre fermentation in the hindgut generates heat, helping horses maintain body temperature in cold weather — far more effectively than a grain feed.
Types of Forage
Hay
Hay is the most common conserved forage in the UK. Quality varies enormously depending on grass species, stage of cut, and how it was made and stored. Good hay should smell sweet, feel dry and slightly dusty (but not excessively so), and be free of mould, weeds, and foreign objects.
- Meadow hay: Cut from permanent pasture containing a mix of grasses and herbs. Generally lower in sugar and energy than seed hay, making it suitable for most horses.
- Seed hay (ryegrass): Cut from sown grass leys, typically higher in energy and sugar. Better suited to horses in harder work.
- Timothy hay: A popular option for horses prone to weight gain or laminitis, as it tends to be lower in sugar than ryegrass hay.
Haylage
Haylage is grass that has been wilted to a higher moisture content than hay (typically 30–50% moisture) and sealed in plastic wrap to ferment. It is more digestible than hay, higher in energy, and largely dust-free (see our full guide to haylage for horses) — making it an excellent choice for horses with respiratory conditions such as RAO (heaves).
However, haylage must be fed within 3–5 days of opening a bale, as it spoils rapidly once exposed to air. It is also calorie-dense, so horses prone to weight gain may need restricted quantities.
Pasture
Fresh grass is the horse’s natural diet and provides excellent nutrition when managed well. Key considerations:
- Grass sugar content (water-soluble carbohydrates) peaks on sunny days following cold nights — a high-risk time for laminitis-prone horses
- Spring and autumn flushes produce rapid grass growth with high sugar content
- Strip grazing or using a grazing muzzle helps control intake for good doers
- Overgrazed pasture provides poor nutrition — horses may need supplementary hay even when turned out
Chaff and Short-Chop Forage
Chaff (chopped hay or straw, sometimes with added oil or herbs) is a useful addition to hard feeds. It slows the rate of eating, encourages chewing, and adds fibre to each meal. Most feed manufacturers produce bagged chaff products designed to complement their concentrate ranges.
Hard Feed and Concentrates
Not every horse needs hard feed. Many horses in light work or good condition on quality forage need nothing more than a feed balancer to top up vitamins and minerals. Hard feed should only be introduced when forage alone cannot meet the horse’s energy or nutritional requirements.
Straights
Traditional “straights” are individual feed ingredients:
- Oats: The traditional British horse feed. High in fibre relative to other cereals, easily digested, and palatable. Can make some horses excitable.
- Barley: Higher in energy than oats but harder to digest. Usually fed micronised, flaked, or boiled — never whole and raw.
- Sugar beet: An excellent source of digestible fibre and energy. Must be soaked thoroughly before feeding (unmixed sugar beet expands dramatically and can cause choke or colic).
- Linseed: Rich in omega-3 fatty acids. Traditionally boiled before feeding; now available as micronised meal or oil.
Compound Feeds
Commercial compound feeds (cubes, nuts, mixes, and coarse mixes) are formulated to provide a balanced diet when fed at the manufacturer’s recommended rate alongside forage. They are convenient and take the guesswork out of balancing nutrients. Types include:
- Cool mixes: High-fibre, low-starch feeds for horses in light work or good doers
- Conditioning feeds: Higher in calories, designed to help underweight horses gain condition
- Performance feeds: Higher in energy (often from oil and digestible fibre) for horses in moderate to hard work
- Veteran feeds: Formulated for older horses, often with added joint support and easily digestible ingredients
Feed Balancers
A feed balancer is a concentrated pellet that provides essential vitamins, minerals, and quality protein in a small daily amount (typically 500 g per day). It is the ideal supplement for horses that maintain condition on forage alone but need micronutrient top-up. Many horse owners overfeed concentrates when a balancer would do the job more efficiently.
Vitamins, Minerals, and Supplements
Salt
Every horse needs access to salt (sodium chloride). Forage and most compound feeds are low in sodium, so a salt lick or loose salt in the feed is essential. A 500 kg horse in light work needs approximately 25–50 g of salt per day, with higher requirements in hot weather or during hard work.
Key Minerals
- Calcium and phosphorus: Critical for bone health. The diet should contain a calcium-to-phosphorus ratio between 1.5:1 and 2:1. Cereal grains are high in phosphorus and low in calcium, so grain-heavy diets may need calcium supplementation.
- Magnesium: Important for muscle and nerve function. Deficiency can contribute to excitability and muscle tension.
- Selenium: An essential trace element, but toxic in excess. UK soils are generally low in selenium, so most horses benefit from supplementation via a feed balancer or compound feed.
Vitamins
Horses synthesise vitamin C and B vitamins in the hindgut, so supplementation is rarely needed in healthy horses on a forage-based diet. Vitamins A, D, and E must come from the diet:
- Vitamin A: Abundant in fresh grass; levels decline in conserved forage over time
- Vitamin D: Synthesised through sun exposure; stabled horses in winter may benefit from supplementation
- Vitamin E: An important antioxidant, particularly for horses in hard work. Levels are high in fresh grass but drop significantly in hay
Water Requirements
A horse in light work typically drinks 25–55 litres of water per day, depending on the weather, workload, and diet (horses on dry hay drink more than those on haylage or grass). Clean, fresh water should be available at all times — both in the stable and in the field.
In cold weather, horses may drink less if the water is very cold. Adding a small amount of warm water or using a frost-free trough can help maintain intake. Dehydration increases the risk of impaction colic, particularly in winter when horses eat more dry hay.
Feeding Different Types of Horse
Good Doers and Native Breeds
Breeds such as Welsh Cobs, Connemaras, and most mountain and moorland ponies are naturally efficient metabolisers. The same applies to most native British breeds, from the Highland to the Welsh Mountain Pony. They typically need forage only, with a feed balancer for vitamins and minerals. Restrict grazing in spring and autumn, and use a grazing muzzle if needed. Monitor body condition regularly.
Poor Doers and Thoroughbred Types
Thoroughbreds and fine-coated breeds often need additional calories to maintain condition. Increase forage quantity and quality first (ad-lib haylage is often effective), then add oil (vegetable oil or a high-fat supplement) for slow-release energy. Avoid relying on large grain feeds, which can cause digestive issues.
Horses in Hard Work
Performance horses, eventers, and racehorses have higher energy demands. Increase calories through oil, digestible fibre sources (sugar beet, alfalfa), and appropriate compound feeds rather than simply adding more cereal grain. Electrolytes should be replaced after strenuous exercise, particularly in hot weather.
Veterans
Older horses (typically 15+) may have reduced dental function, making long-stem forage difficult to chew. Soaked hay cubes, short-chop forage, or high-fibre mashes can replace hay partially or fully. Senior horses often benefit from higher-quality protein to maintain muscle mass and topline.
Laminitis-Prone Horses
Horses with a history of laminitis or EMS need a low-sugar, low-starch diet (our laminitis management guide covers this in detail). Soaking hay lowers water-soluble carbohydrates, but it does not reliably make hay safe, and the widely repeated “soak for 6 to 12 hours” rule overstates what it achieves: Longland, Barfoot & Harris (Vet Rec 2011) measured a mean 27% WSC loss (range 6-54%) after up to 16 hours, with seven of the hays tested still above the 100 g/kg DM ceiling suggested for laminitic animals. Warm water leaches more, not less – Longland et al. (Vet Rec 2014) recorded 28% at 8°C against 46% at 16°C over the same 16 hours – so a short warm soak is not the equivalent of a long cold one. Have the forage analysed, restrict or eliminate grazing, and avoid cereal-based feeds entirely. A low-calorie feed balancer provides essential nutrients without excess energy.
The Golden Rules of Horse Feeding
- Feed little and often. The horse’s small stomach and constant acid production mean frequent, small meals are far safer than two large ones. Aim for at least 2–3 forage feeds per day if the horse is stabled.
- Feed plenty of forage. A minimum of 1.5% bodyweight in forage daily. Never restrict forage below this level without veterinary guidance.
- Make changes gradually. Introduce any new feed over 7–14 days, gradually increasing the new feed while decreasing the old. This applies to changes in forage as well as concentrates.
- Feed by weight, not volume. A scoop of oats weighs differently from a scoop of mix. Weigh feeds to ensure accuracy.
- Feed according to workload. Increase feed when work increases; reduce feed on rest days. Overfeeding an under-worked horse causes azoturia (tying up) and weight gain.
- Ensure clean, fresh water is always available. Dehydration impairs digestion and increases colic risk.
- Do not exercise immediately after feeding. Allow at least one hour after a concentrate meal before work, to allow the stomach to begin emptying.
- Feed something succulent daily. Carrots, apples, or soaked sugar beet add moisture and variety to the diet.
Seasonal Feeding Considerations
Winter
Energy requirements increase in cold weather as the horse burns calories to maintain body temperature. Increase hay rations rather than hard feed — fibre fermentation generates more internal heat than grain digestion. Ensure water doesn’t freeze, and monitor condition under winter rugs, as weight loss can be hidden.
Spring
The spring grass flush brings a surge of sugar-rich growth. This is the highest-risk period for laminitis in susceptible horses. Limit turnout time, use strip grazing, or apply a grazing muzzle. Reduce hard feed as grass quality improves.
Summer
Ensure adequate hydration and provide salt or electrolytes, particularly for horses in regular work. Grass quality may decline in dry spells — supplementary hay may be needed even in summer if pasture is poor.
Autumn
A second grass flush occurs in many areas as rain returns after summer. Similar laminitis precautions apply as in spring. Begin increasing hay rations as grass growth slows and prepare for the transition to winter feeding.
Common Feeding Mistakes
- Overfeeding concentrates, underfeeding forage. The single most common error. Many horses receive far more hard feed than they need and not enough hay.
- Sudden diet changes. Switching feed overnight disrupts the hindgut microbiome and can trigger colic or laminitis.
- Feeding mouldy hay or feed. Mould produces mycotoxins that can cause respiratory disease, colic, and liver damage. Always inspect hay before feeding.
- Ignoring body condition. Regularly score your horse’s condition and adjust the diet accordingly. A rug can hide significant weight gain or loss.
- Feeding by eye rather than weight. Invest in a feed scoop scale or kitchen scales. Accuracy matters.
- Not providing salt. Most UK forage and compound feeds are low in sodium. A salt lick or 25 g of table salt in the feed daily is a simple, cheap fix.
