Before diving into feeding strategies, it helps to understand why your horse lost condition in the first place. A horse doesn't suddenly become thin without reason. Identifying the root cause is the first and most important step when feeding horses for weight gain.
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Health Issues Come First
If your horse has dropped weight without any obvious change in management, call your vet. Conditions like gastric ulcers, parasites, chronic pain, liver or kidney problems, and infectious disease can all cause weight loss — sometimes without any obvious signs other than a shrinking topline or visible ribs. A heavy worm burden, for example, not only steals calories but can damage the gut lining over time, reducing your horse's ability to absorb nutrients at all.
Dental Problems Are a Common Culprit
A horse with sore or uneven teeth simply cannot chew properly. You might notice partially chewed food dropping from the mouth (known as quidding), unchewed grain in the manure, or a reluctance to accept the bit. Adult horses should have their teeth checked at least once a year, and senior horses twice a year. By the time a horse reaches its late twenties, its teeth may be worn down to the point where long-stemmed hay is no longer manageable, and the diet needs to change accordingly.
Social and Environmental Factors
A horse at the bottom of the herd pecking order may be chased away from the feeder repeatedly throughout the day. Even if you're putting out enough feed, that horse simply isn't getting its share. Separating lower-ranking horses at mealtimes — or spreading hay across multiple feeding points — can make a real difference.
Extreme temperatures also play a role. In winter, horses burn significantly more energy keeping warm. For every 1°C drop below a horse's lower critical temperature threshold, energy requirements increase. Horses without adequate shelter or blankets in cold conditions will struggle to hold weight no matter how much you feed them. On the opposite end, very hot weather reduces appetite, meaning horses eat less at the exact time they need hydration and feed most.
How to Assess Your Horse's Condition Before You Feed
You cannot develop an effective feeding plan without knowing where your horse currently sits. Two tools help here: body condition scoring and body weight estimation.
Body Condition Scoring
The Henneke Body Condition Score (BCS) runs from 1 (extremely thin) to 9 (extremely obese). Most horses should sit between 5 and 6. A score of 5 means you cannot see the ribs but can feel them easily when you run a hand along the barrel. Scores of 3 or below indicate a horse that is genuinely underweight and needs attention. A score of 1 or 2 requires a re-feeding plan developed with a vet or equine nutritionist — bringing these horses back too fast can cause serious digestive complications.
Estimating Body Weight
A weight tape gives a reasonable estimate and is worth using regularly so you can track changes over time. Some breed-specific equations also exist — for example, Thoroughbreds, Warmbloods, and Arabians each have different ideal weight formulas based on their height and body length measurements. Knowing your horse's weight helps you calculate feed quantities accurately rather than guessing.
Track Your Baseline
Weigh your feeds before you change anything. Even hay flakes vary in weight, and many owners are surprised to find they've been feeding considerably less than the manufacturer's recommended serving. Take photographs in good light on flat ground — they give you an objective record that your eye alone won't provide.
Feeding Horses for Weight Gain: Where to Start
Once you've addressed any health issues and established a baseline, you can build a feeding plan. The golden rule is to go slowly. All diet changes should be introduced gradually over at least two weeks to allow the gut to adjust. Rushing the process risks colic, laminitis, and digestive upset.
Set a Realistic Goal
A safe rate of weight gain is around 0.25 to 0.5 kg per day. To put that into context, if a 500 kg horse needs to go from a BCS of 4 to a 5, it needs to gain roughly 20 to 25 kg. At half a kilogram per day, that's a 40 to 50-day process — not a weekend fix.
Step One: Get the Forage Right
Forage is the foundation of every horse's diet, and it's the first thing to evaluate when feeding horses for weight gain. A horse needs a minimum of 1.5 to 2% of its body weight in forage daily just for maintenance. To encourage weight gain, that needs to increase to around 2.5 to 3%.
For a 500 kg horse, 2.5% works out to 12.5 kg of forage per day. If your horse has been getting less than this, simply increasing the hay ration may be enough to get the scales moving in the right direction.
Choose High-Quality Hay
Not all hay is equal. Good-quality hay is leafy, green, and soft to the touch. If a handful of hay feels stiff and pokes your palm, it's too mature and won't offer the calorie density you need. If you're not sure about your hay's nutritional value, you can send a sample to a laboratory for analysis.
Add Lucerne (Alfalfa)
Lucerne hay is higher in both calories and protein than most grass hays, making it an excellent addition when feeding for condition. A flake or two of lucerne mixed into a grass hay ration can boost the overall energy content significantly. Lucerne cubes and pellets are a good option for horses that tend to waste loose hay.
Consider Super Fibres Like Beet Pulp
Sugarbeet pulp is a highly digestible fibre source with a similar calorie level to some cereal grains, but without the starch load. It's palatable, easy to add to a ration, and excellent for horses that need more calories without more heating feeds. Introduce it slowly — start with around 500 g dry weight per day and build from there. Beet pulp is not a complete feed on its own, so it works best alongside a balanced concentrate or hay ration.
Step Two: Add Fat for Safe Calorie Density
If your horse is consuming all the forage it wants and still not gaining weight after a few weeks, it's time to add more calories. Fat is the safest and most energy-dense way to do this. While carbohydrates provide roughly 4 calories per gram, fat provides around 9 — more than double.
Vegetable Oil
Adding vegetable oil to a feed bucket is one of the simplest and most affordable options. Corn, canola, or sunflower oil all work well. Start with a quarter cup per day and increase by a quarter cup every few days, up to a maximum of about 500 ml daily for a full-sized horse. If you introduce oil too fast, you'll see greasy, loose manure — a sign to slow down. Store oil in a cool place and sniff it before each use, as rancid oil is harmful.
Rice Bran
Rice bran is another fat-rich option that most horses enjoy. It's also a source of vitamin E and fibre. One important note: rice bran is high in phosphorus, which can interfere with calcium absorption. If you're feeding natural rice bran, balance it with a calcium source like lucerne, or choose a commercially prepared rice bran product that has been formulated with added calcium.
High-Fat Commercial Feeds
Equine nutrition has come a long way, and many quality feeds are now formulated with elevated fat levels specifically for hard-keeping horses. A performance or conditioning feed with 10 to 12% fat can make a meaningful difference without the risks that come with piling on large quantities of grain. Choosing the right commercial feed for your horse's life stage and workload is important — a feed designed for working performance horses will have a different profile to one formulated for a mature leisure horse.
Step Three: Use Concentrates Wisely
Grains and sweet feeds have long been the go-to solution for thin horses, but they come with risks. When a horse consumes more starch in one meal than its small intestine can process, the excess ferments in the hindgut. This disrupts the microbial balance and can lead to colic and acute laminitis. No horse is immune to this risk if the starch load is large enough and introduced too quickly.
Keep Meal Sizes Sensible
Never feed more than 0.5% of your horse's body weight in concentrate per meal. For a 500 kg horse, that's 2.5 kg per feeding. If your horse needs more than this to gain weight, split the daily ration into three or four smaller meals rather than increasing individual serving sizes.
Choose the Right Product for Your Horse
Select a concentrate formulated for your horse's specific situation. A young horse in heavy work needs a different feed profile to a senior horse with worn teeth or a broodmare in late pregnancy. Read the label and feed at recommended quantities — many owners underfeed concentrates and then supplement haphazardly, ending up with an unbalanced diet.
Feeding Senior Horses for Weight Gain
Older horses present a unique challenge. As horses age, their teeth wear down and their digestive systems become less efficient at extracting nutrients from feed. A senior horse may be eating what looks like a reasonable ration but absorbing far less of it than a younger horse would.
If your senior horse can no longer chew long hay effectively, a complete feed — one designed to replace forage entirely — is the right move. These feeds are formulated with enough fibre to meet daily requirements and can be fed in larger quantities to compensate for the reduced hay intake. If the horse struggles with even soft pellets, the feed can be soaked into a mash with warm water.
Senior horses also benefit from being separated at feeding time to ensure they aren't being pushed off their feed by younger, more dominant horses.
Hard Keepers: Horses That Always Need More
Some horses are simply wired to need more calories than average. Thoroughbreds and Standardbreds are classic examples — breeds with fast metabolisms that burn through feed quickly. Horses that are naturally high-strung, stallions during the breeding season, performance horses in heavy work, and pregnant or lactating mares all fall into this category too.
For these horses, the approach to feeding for weight gain is the same as for any underweight horse, but it's an ongoing commitment rather than a short-term fix. A consistent regime of high-quality forage, added fat, and appropriate concentrates — adjusted for workload and season — is what keeps these horses in condition year-round.
Practical Tips for Getting Results
Start by weighing your feeds so you have an accurate picture of what your horse is actually eating. Increase forage first, then add fat, then adjust concentrates if needed. Make every change gradually. Separate horses that are being bullied away from feed. Provide constant access to fresh, clean water — dehydration suppresses appetite. In winter, bring underweight horses in at night and use a blanket to reduce the calories burned on warmth. In summer, bring horses in during the hottest part of the day to prevent heat-related appetite loss.
Check your horse's body condition once a week. Take photos. Weigh when you can. Keep notes. It takes time to turn a thin horse around, but with the right approach, the results are absolutely achievable.
If after several weeks of consistent effort your horse is still not gaining, consult an equine nutritionist. Sometimes the solution lies in a combination of factors that takes an expert eye to untangle.
Frequently Asked Questions
How long does it take for a horse to gain weight?
It depends on how much condition the horse needs to regain, but a safe and realistic target is 0.25 to 0.5 kg of gain per day. A horse that needs to move up one full body condition score will typically need 40 to 60 days of consistent, correct feeding to get there. Rushing the process by overfeeding — especially with grain — risks colic and laminitis, so patience is essential.
What is the best feed to put weight on a horse?
There is no single best feed — it depends on why the horse is underweight and what it is already eating. The most effective approach starts with high-quality forage like good grass hay or lucerne, then adds a fat source such as vegetable oil or rice bran, and finally adjusts concentrates if needed. A high-fat commercial feed formulated for hard keepers or performance horses is often the most convenient and balanced option.
How much should I feed an underweight horse per day?
ody weight in total feed daily. For a 500 kg horse, that is between 12.5 and 15 kg of feed per day, with forage making up the bulk of it. Concentrates should not exceed 0.5% of body weight per meal — for a 500 kg horse, that is no more than 2.5 kg of grain or pellets at a time.
Can I just give my horse more grain to help it gain weight?
Feeding large amounts of grain is not the safest route to weight gain. When a horse eats more starch than its small intestine can handle in one sitting, the excess ferments in the hindgut and disrupts the gut's microbial balance — which can lead to colic or laminitis. Rather increase forage and add fat first. If concentrates are needed, choose a high-fat, lower-starch feed and divide it across multiple small meals throughout the day.
Should I call a vet before changing my horse's diet for weight gain?
Yes, especially if the weight loss has been unexplained or sudden. A vet check rules out underlying causes like parasites, ulcers, dental problems, or organ disease — all of which can prevent weight gain no matter how well you feed. Treating the root cause is always the first step. Once your horse has a clean bill of health, you can confidently build a feeding plan knowing the feed will actually be utilised.
