Forage is the foundation of every horse's diet. It keeps the hindgut working, satisfies the strong need to chew and, for many horses, supplies most of the energy they need. Yet "ad lib hay" and "a couple of slices" are still common ways to describe a ration, which makes it hard to know whether a horse is getting too much, too little or about right. The figures used by vets and welfare charities are straightforward once you understand dry matter and get into the habit of weighing.
The headline figures
Forage requirements are usually expressed as a percentage of bodyweight per day. The European College of Equine Internal Medicine's 2015 consensus statement on gastric ulcers recommends that hay-fed horses receive a minimum of 1.5kg of forage dry matter per 100kg of bodyweight per day, which is 1.5% of bodyweight. UK feed nutritionists widely use the same 1.5% figure as the minimum for long-term health and welfare.
For a maintenance ration, Redwings Horse Sanctuary's weight management guidance links the percentage to body condition score. On its 0 to 5 scale, a horse at score 3 (ideal) is fed around 2% of bodyweight, a horse at 3.5 or above around 1.5% to lose weight, and a horse at 2.5 or below around 2.5%. World Horse Welfare suggests working on about 2 to 2.5% of ideal bodyweight for the total daily ration.
| Bodyweight | 1.5% per day | 2% per day | 2.5% per day |
|---|---|---|---|
| 300kg | 4.5kg | 6kg | 7.5kg |
| 400kg | 6kg | 8kg | 10kg |
| 500kg | 7.5kg | 10kg | 12.5kg |
| 600kg | 9kg | 12kg | 15kg |
Grazing counts towards the total, which is why horses on good grass often need little or no extra forage in spring and summer.
Dry matter versus as-fed weight
Dry matter is what is left once the water is removed. Hay is made by drying grass until its water content falls below about 20%, while haylage typically contains 40 to 50% water. That means a kilogram of haylage provides much less dry matter than a kilogram of hay.
To convert a dry matter target into an as-fed weight, divide by the dry matter content. A 500kg horse needing 1.5% of bodyweight as dry matter needs 7.5kg of dry matter a day. If your hay is 85% dry matter, that is about 8.8kg of hay as fed. If your haylage is 55% dry matter, it is about 13.6kg as fed. A forage analysis tells you the actual dry matter of your batch and is worth doing if you are managing weight closely.
Some practical guides, including the Redwings calculator, are written in terms of hay weighed dry before soaking rather than strict dry matter. For dry hay the difference is modest, but for haylage it is large, so check which basis any figure uses.
Weigh your horse and your forage
Percentages are only as good as the weights behind them. Use a weighbridge if you can, or a weigh tape, and use the same tape each time so you can track changes. World Horse Welfare recommends fat scoring at the same time as weighing, and your vet can help you estimate the ideal weight of an overweight horse.
Forage needs weighing too. Redwings notes that bales can vary considerably, citing one study that found a range of 13 to 27kg. A set of hanging scales lets you weigh each haynet, and Redwings advises weighing hay dry, before soaking or dampening, so you are not weighing water. Once you know what a typical net or section weighs, you can adjust it accurately.
Good-doers and weight loss
Good-doers, including many native ponies and cobs, are where forage rationing matters most. Even so, the floor of 1.5% of bodyweight still applies. Redwings advises only going below 1.5% if your vet recommends it, and World Horse Welfare says that dropping to 1.5% for greater weight loss should only happen under veterinary supervision. Crash dieting is dangerous and counterproductive.
- Aim for steady loss. Redwings gives around 1% of body mass per week as a safe rate.
- Reduce concentrates before forage, and look at exercise too.
- Feed a balancer or broad-spectrum supplement so the restricted ration still supplies vitamins and minerals. Our comparison of feed balancers and vitamin and mineral supplements explains the options.
- Introduce grazing muzzles gradually; World Horse Welfare suggests a maximum of 10 to 12 hours a day.
The ECEIM statement also advises that straw should not be the only forage, so take advice before using straw to stretch a ration.
Soaking hay
Soaking is widely used to reduce the water-soluble carbohydrate (sugar) content of hay for good-doers and horses prone to laminitis. Research by Longland and colleagues, published in the Veterinary Record in 2011, found that soaking UK hays for up to 16 hours in water at about 8°C removed an average of 27% of their water-soluble carbohydrate. Results varied between hays, and seven hays still exceeded the suggested limit for laminitic animals after soaking. Crude protein did not change significantly.
Redwings suggests soaking for 12 to 16 hours in tepid water to reduce calorie content, and World Horse Welfare refers to a 12-hour soak. Longer soaking also washes out dry matter and can increase bacterial contamination, so feed soaked hay promptly and dispose of the water carefully. Always weigh the hay before soaking. Because results are so variable, a hay analysis is the most reliable way to choose low-sugar forage in the first place.
Slow feeders and small-holed nets
Horses are trickle feeders, and World Horse Welfare advises that they should not go without forage for more than 4 to 6 hours. When the ration is restricted, making it last is as important as getting the amount right. Small-holed or double haynets create a trickle-feeding effect, and Redwings suggests splitting the daily ration across three haynets.
Research supports the approach. A 2024 study in Icelandic horses found that haylage in a haynet or hayball took longer to eat than haylage fed from a manger or the floor, extending daily intake time by around 13%. A 2024 study in ponies found a partially filled haynet was the most effective way to lengthen feeding time, while a slow-feeder hay box reduced intake rate with a more natural head position. Spreading forage through the day also supports the stomach; our comparison of gut balancers and gastric supplements explains why, and our page on hindgut health covers the other end of the gut.
Changing forage safely
Whenever you change the type, batch or amount of forage, do it gradually. The British Horse Society advises making diet changes over at least 10 to 14 days so gut bacteria can adapt. Our guides to diet changes and turnout and winter gut health cover seasonal transitions in more detail.