A guide to managing a horse’s weight on grass

When you are designing the ideal diet for your horse, there are many things to consider. A healthy horse should eat 1.5%–3.1% of their body weight each day[i], in either forage or cereals. Forage are bulky, high fibre and low starch options like hay, haylage, and grass. Cereals include oats barely, and maize, and are high in starch and more energy-dense. When your horse is grazing, it can be difficult to monitor their diet and keep tabs on their weight. For detailed information on what a horse’s diet should contain, head over to our guide on what horses eat.

Maintaining your horse’s ideal weight is essential for their wellbeing, and will help to prevent health problems such as laminitis, a painful condition that affects horses’ hooves and is more likely to occur in overweight animals. It’s important to include pasture management in your horse care plan, so you can maintain your equine friend’s health while giving them all the nutrients they need.

So, in this guide we’ll be covering:

• How much should your horse eat?
  • How much of your horse’s diet should be grass?
  • Does your horse need to graze?
  • How long should a horse graze?
• Can a horse eat too much grass?
  • Laminitis
    • Signs of laminitis in horses
    • How to prevent laminitis in horses
  • Colic
    • Signs of colic in horses
    • How to prevent colic in horses
  • How to restrict grazing in horses
    • Turn your horse out for less time
    • Restrict the grazing area
    • Use a grazing muzzle when turning out
    • Stop the horse grazing while riding
  • Other ways to monitor your horse’s diet
    • Use small holed haynets
    • Choose your hay carefully
    • Change your horse’s bedding
    • Increase the horse’s physical activity

How much should your horse eat?

While your horse should eat 1.5%–3.1% of their body weight every day, the exact amount depends on their lifestyle and build. For example, lactating mares typically need more food, eating around 2.8% of their body weight each day.

Other horses might eat closer to 2%, and this will depend on how much physical activity your animal has each day, and one their current body condition score. A horse that mainly goes on relaxed hacks will need less calories than one competing in eventing or showjumping competitions.

It’s a good idea to calculate a healthy weight for your horse based on their size and workload. To do this, you can use our horse height and weight guide for detailed information. If you aren’t sure how much your horse should be eating in order to maintain a healthy weight, you should consult your vet. This is particularly advisable if your horse is notably under or overweight, as they can help you devise the right diet for your four-legged friend.

It’s also worth noting that some new research conducted at Centenary University, New Jersey, has found that increased pasture time can increase fitness in horses, and therefore reduce instances of soft tissue injury. These injuries are often responsible for horses needing rest time and rehabilitation, so it’s advisable not to reduce their grazing time too much, as maintaining it will also allow them to exercise more frequently.

How much of your horse’s diet should be grass?

Most horses will be happiest with a combination of both grass and forage. This is largely because grazing conditions are usually not reliable — grass can’t grow as quickly as horses can eat it, so you’ll need to rotate the horse around fields to make sure they always have access to quality grass.

This can often be difficult due to space constraints, or because the weather and soil doesn’t support the level of grazing that horses need. So, a good balance is to work out how much grass your horse will be consuming, and make up the rest with hay, haylage and hay cubes.

Does your horse need to graze?

Grazing is a very important part of horses’ diets, because live grass contains certain nutrients that are not present in forage, according to Horse Network. When grass is cut for hay, the levels of vitamins C, E, and B in the grass drop. Vitamin A also reduces gradually, but the affect on this vitamin is slower, and therefore most hay you purchase will contain adequate amounts of this nutrient.

It’s important to note however, that pasture might also not contain enough calcium for either lactating mares, or young, fast-growing horses and foals. Other nutrients such as phosphorous, copper and zinc also need to be added using other food sources. So other elements of your horse’s diet are just as important.

How long should a horse graze?

So, you’ve decided to balance your horse’s diet between grass and roughage. Now, you have to decide how long to turn your horse out for.

It’s advisable to make an estimate of how much grass your horse will be intaking during the time they’re in the field. This can help you work out how long to let them graze for, and how much hay — if any — you need to add to their diet.

A 450kg horse consumes approximately 4.5kg if they are turned out for half the day (around six hours). This is about 1% of their body weight, and it means that if you let your horse graze for half of the day, you will need to make up the other 1% (about half of their intake) with forage.

This can be a combination of hay and haylage, but it should be noted that grass contains more calories than both hay and haylage, and that should be accounted for in your diet planning. It’s important to also note that newly grown, lush pasture contains more calories than older grass. So, factor in the season and type of grass when deciding how long to let your horse graze for. In spring, you’ll often need to shorten their pasture time, as this grass is particularly lush and calorie-dense.

Can horses eat too much grass?

In short, yes, horses can eat too much grass. As grass contains more calories that hay or haylage, it’s easy for your equine friend to pack on the pounds if they are allowed to graze freely all through the day. Horses love their pasture, and will continue to eat as long as they are outside, if they are able to. But what kinds of problems can be caused by your horse eating too much grass?

Problems caused by overfeeding

Laminitis

One of the most well-known problems of too much grazing is laminitis, a painful disease that affects horse’s hooves. Laminitis is the inflammation of the laminae of the foot, as explained by the RSPCA.

The laminae of the foot are the soft tissues that attach the pedal bone of the foot to the wall of the hoof. When this is inflamed, it is very painful for the horse and in extreme cases it can lead to the pedal bone separating from — or even rotating within — the hoof wall.

In severe cases, laminitis can be fatal. Once a horse has had a case of laminitis, they are particularly susceptible to more flare ups, as laminitis can be managed, but not totally cured. This means that prevention of laminitis is very important, as is giving your horse excellent hoof care.

Signs of laminitis in horses

The signs of acute laminitis can often appear suddenly, and be severe:

• Inability or reluctance to walk.
• Lying down and being unwilling to get up again.
• Appearing lame, especially when walking on a hard surface.
• The afflicted foot will have an increased pulse.
• Leaning back onto the hind feet to take weight off the injured front feet.
• In chronic sufferers, the heel of the hoof will often grow faster than the front.

A regular sufferer of this disease will additionally show some lingering signs of previous laminitis occurrences, such as having the appearance of growth rings around the hoof wall.

Any signs of laminitis should warrant an immediate call to your vet, who can assess the situation. It is crucial that treatment is administered quickly and accurately to make sure the horse has pain relief, and to prevent long-lasting damage to the foot.

How to prevent laminitis in horses

Preventing laminitis in horses is largely a matter of keeping the animal at a healthy weight. Being overweight can put additional pressure on the laminae of the hoof, which can cause a bout of laminitis.

The good news is that this means you can keep laminitis away by controlling your horse’s diet.

• Feed little and often, to mimic the horse’s natural feeding pattern and help digestion.
• Give your horse low-sugar, low-carbohydrate and high-fibre food sources.
• Avoid feeding cereal mixes or molasses products, unless your horse is under very hard work and needs additional calories in their diet.
• A probiotic can help maintain the hindgut, so ask your vet about this addition.
• Do not turn the horse out onto lush grass, especially in spring.
• Ensure a farrier attends to the horse every four to five weeks, as this will help keep the hooves healthy.

Colic

Colic is one of the most common causes of death in horses, according to the University of Liverpool. However, the prognosis is much better than it used to be, because we now have more accurate methods of diagnosis and more effective treatments for the condition. Catching the disease early, and using surgical treatment for more serious cases, are the best ways to combat the illness.

Simply put, colic is a word used to describe abdominal pain, as summarised by the Blue Cross. It is often caused by a problem in the gut itself, though it can be an indicator of issues in other organs. It’s commonly caused by grass-feeding stretching the horse’s gut and causing discomfort.

Horses are sensitive to pain in their intestinal tract, and eating too much grass, too fast can cause a nasty bout of colic for your horse. The condition is potentially fatal, but easy to prevent once you know how.

Signs of colic in horses

The signs of colic in horses can be fairly subtle, but when you have a close relationship with a horse it’s often easier to tell when your horses is uncomfortable. Keep an eye on whether your horse is acting out of character.

• Being restless and pawing at the ground
• Kicking at their stomach in irritation
• Rolling, or just attempting to roll
• Increases breathing and heart rate
• Sweating

If your horse shows any signs of colic, call your veterinarian immediately, as this issue has the potential to be fatal. By catching it early, you can get your horse treated as soon as possible. It’s important to pay special attention to any horses that have suffered from colic previously.

How to prevent colic in horses

Preventing colic is much easier than treating it. There are plenty of things that you can do to ensure that the exciting, lush grass of spring doesn’t lead to a medical problem for your four-legged friend.

• Avoid grazing your horse on pasture that’s very sandy.
• If you are bringing your horse back into work after a break, make changes to exercise and feed slowly, increasing grazing time gradually.
• Have a regular daily routine.
• Have regular dental checks — poorly chewed food increases intestinal irritation.
• Ration lush spring grass, and treat it as a diet change in itself.
• Keep up to date with your vet’s worm control programme.
• Maintain a high-fibre diet, using hay as well as pasture.

How to restrict grazing in horses

There are lots of measures that you can take to avoid both laminitis and colic, as well as to control your horse’s weight. But how can you restrict your horse’s intake when they are out grazing? It’s difficult to assess how much grass your horse is eating, and to reduce the amount if needed, but it is possible.

If your horse is gaining weight and you want to prevent conditions such as laminitis, you can bring their food intake down so that they are eating 1.25%–1.5% of their body weight until they reach a healthier weight. This includes their forage intake, so you’ll need to work out your horse’s weight, and then calculate how much roughage to give them. Always consult a vet when designing a weight loss plan, to ensure that it will be healthy for your horse.

How much roughage versus how much grass they consume is very individual, even while dieting, but it’s worth considering that grass contains more calories. So, if you’re concerned about your horse’s weight, it’s worth considering having their diet be 60% roughage, and slightly less pasture.

There are also various practical measures you can take to control your horse’s pasture intake.

Turn your horse out for less time

Limiting your horse’s grazing time is one of the easiest ways to reduce their food intake, and it is especially useful because grass is higher in calories than hay or haylage. This means that you can reduce the highest calorie food in your horse’s intake, and then assess how much hay they’ll need. Try letting your four-legged friend out to pasture for half a day instead of the whole day, and then offer hay to make up the rest of their daily needs.

The only concern with this method is that some horses can become wise to the measures you’re trying to impose, and eat the grass quicker. Some horses can even consume the amount they would normally eat in a whole day in half the time, because they know they’ll be brought in soon. So, try to monitor how quickly your horse eats: watch them for half an hour or so, and see if they are eating at their usual pace. If not, you might find other methods more effective at controlling your horse’s weight.

Restrict the grazing area

Lush grass contains more calories than rougher grass, so you can restrict your horse’s grazing space to ensure that they can’t reach the higher calorie grass. This will ensure they take in less carbohydrates and sugars, and allows you to control exactly what they are eating.

This trick can also work on horses who have figured out that you will turn them out for less time. When they are still eating lush pasture, they can simply work their way through it quicker, but when their grazing area is restricted, they are limited to lower calorie food sources.

If you go for this method, use a secure fencing solution, such as electric or wooden fencing, and make sure to safety test it prior to use with horses. If you use land owned by a farmer or livery stable for grazing, speak to them about cornering off some space for your horse, and agree any measures with them prior to implementing anything.

Use a grazing muzzle when turned out

Another way to limit your horse’s grass intake is to use a grazing muzzle. Again, this is a useful measure for when your horse understands they have less time to graze, and so tries to increase how much they eat. Grazing muzzles don’t prevent the horse from eating, but instead restrict the amount of grass they are able to bite off and swallow, thereby slowing down their pasture consumption.

Another benefit of using a grazing muzzle is that it means your horse can continue to spend time in the pasture, without overeating. This is great for them as it allows them freedom of movement, and encourages exercise. So, it’s an excellent way to increase your horse’s exercise quantity, especially if you don’t have time to ride them even more than you do. Horses are also evolved to be trickle feeders, so they are suited to this type of eating and will adjust very well.

When starting to use a muzzle, try taking some extra measures to ensure your horse is comfortable in it, and it’s working properly. Check that the muzzle fits properly when you first put it on, and supervise your horse grazing in it for a while. This way, you can both check that the muzzle is working and reducing the amount of grass they eat, and also that the muzzle is safe and comfortable. Look out for it slipping off your horse’s nose, restricting their movement, or irritating them.

Stop the horse grazing while riding

You might successfully limit your horse’s intake of grass while they are out in their paddock, but they might also lean down and start trying to graze when you are out riding. Not only is this frustrating, but it can also be a safety issue, especially when you are hacking around cars, pedestrians, and other riders. So, it’s important to know some methods for how to stop a horse grazing while riding.

The first thing to note is that horses form habits through repetition, so if you let your horse get away with nibbling at the grass a few times, you might find them doing it more and more. However, don’t worry too much if your horse has already formed this habit, as it’s fairly easy to correct.

If your routine includes letting your horse graze while you brush them, or at a certain grassy patch on the way to their stall, they will expect this whenever you come to get them. So, change up their timetable so they won’t know to expect a grazing break when you’re leading or riding them. If the habit persists, try some groundwork to establish yourself as the authority, and gradually move them into doing groundwork on a grassy area, rather than an indoor school, to test their discipline.

Other ways to monitor your horse’s diet

Keeping tabs on your horse’s pasture consumption will go a long way towards keeping them at a healthy weight, but there are other things you can do to manage their diet when stabled. Having at least half of their food be hay or haylage will give you better control over how many calories they are consuming, and can be very helpful when trying to get their weight down.

So, here are the things you can do to help your horse consume less roughage.

Use small holed haynets

Some research has suggested that using small holed haynets can extend a horse’s eating time, and aid weight loss for horses on limited diets. A small holed haynet works by making the hay more difficult for the horse to get at, as they have to eat it through much smaller gaps in the net. This means they have to eat more slowly, over a longer period.

Horses are grazing animals, meaning they eat small amounts near constantly throughout the day — so having to eat more slowly means that they will eat less overall each day. Having a small holed haynet will also mean they can continue nibbling the way they are used to, and this can combat boredom and give them a sense of keeping their usual routine.

Choose your hay carefully

The type of hay you choose to feed your horse will depend on lots of things, such as height and weight, workload, and the quality of the pasture they graze on. But it’s safe to assume that if your horse needs to lose some weight, then you should be feeding them hay that is of lower nutritional value, with a lower leaf-to-stem ratio.

This doesn’t mean the hay isn’t good, it just means that it was harvested at a later stage, and so it is more mature and less calorific. This means you can feed your horse more of this hay than a more calorically dense choice. Grass hay is a good choice for overweight horses, while alfalfa has a higher calorie count and so can exacerbate problems of gaining weight.

Change your horse’s bedding

While it might sound drastic, you should be aware that horses have been known to resort to eating straw and even shavings when they are on restricted diets. So, you should monitor your horses, and if you notice them eating their bedding straw, replace it with rubber shavings to ensure that they aren’t supplementing the diet that you’ve carefully worked out for them.

Increase your horse’s physical activity

Focusing on diet is a great place to start with controlling your horse’s weight on grass, but exercise is crucial too. The best way to keep your horse at a healthy weight is to combine the appropriate diet with the ideal amount of exercise for their age and breed type.

If you usually exercise your horse once per day, consider gradually increasing the duration of exercise, or upping it to twice per day. Or, you can simply extend your rides by an hour and gradually build up their stamina so they can burn more of the calories they consume. Not only will this help to reduce their weight, but it will improve their cardiovascular health and fitness too.

If you don’t have time to exercise your horse more than you do already, try asking for help. If you stay at a livery yard, ask if someone else would want to take your horse out a few times per week for an extra hack. Or, a friend or family member might enjoy a free ride too.

It can be confusing to design the best diet and grazing plan for your four-legged friend, but by using these tips, you can get yourself off to the best start, and find some methods to limit your horse’s grass intake. This will be especially useful in spring, when that lush grass can really pile on the pounds.

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[1] https://www.thelaminitissite.org/how-much-do-horses-eat.html