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    Daily Diet, Treats And Supplements For Horses: The Basics

    Three horses eat grass outside together.
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    Veterinary Review Initiative
    This resource has been reviewed for accuracy and clarity by a qualified Doctor of Veterinary Medicine with farmed animal sanctuary experience as of February 2024.

    Check out more information on our Veterinary Review Initiative here!

    If you’re reading this resource, there are likely some special horse residents in your life who you’d like to provide the best possible care for! The compassionate lifelong care of horses at animal sanctuaries starts with the food they’re provided.

    When it comes to feeding the individual horses in your care, you may be overwhelmed initially by the number of choices and amount of information out there. By first understanding what a horse’s essential needs are, you can make informed decisions about how to feed and supplement your resident horses, and have the knowledge to back up your choices.

    Understanding The Basics Of A Horse’s Digestive System

    Horses are not ruminants; they are hindgut fermenters. The digestive system of a horse is designed to digest a continuous supply of forage. A host of beneficial bacteria live in a horse’s digestive tract, particularly the large intestine, where they produce the enzymes needed to properly digest forage. Their stomach is relatively small compared to other areas of the digestive tract. The stomach of an average sized horse (around 1,000 lbs or 453kg) can only hold 2-4 gallons (7.5-15.14L) of contents, whereas the small intestine can hold 10-23 gallons (37-87L) within its 50-70 ft (15-21m) length! This is where a lot of digesting happens and important nutrients are absorbed. The large intestine can hold up to 16 gallons (60L)! This means a few things in terms of dietary needs that every caregiver should know:

    • Horses are designed to continuously digest lots of fiber. Their entire digestive system can process a large volume of fiber, simultaneously digesting fiber while horses continue to eat forage, and on and on the process goes.
    • Without a source of bulky fiber to digest, a horse’s bowels are more likely to twist and cause a serious case of colic.
    • While they are designed to continuously digest a lot of fiber, the smaller capacity of a horse’s stomach and small intestines is not conducive to breaking down singular large meals at a single time. The act of chewing releases saliva that assists with the digestive process.
    • Grain should only be used to supplement a horse’s diet when they aren’t receiving all the nutrients from the forage available. Certain breeds, health conditions, and age factors can increase the need to offer grain and other supplements. These decisions should be made with the help of an equine nutritionist or experienced veterinarian.
    • A diet low in forage is sure to cause a host of health problems. Horses need access to forage throughout the entire day. This promotes the health of the hindgut, providing nutrients for the healthy bacteria that live there. 
    • A diet high in grain, especially if it is provided in a single meal, can prove too much for a horse’s stomach and small intestines to properly digest, resulting in rapid fermentation. This can lead to a number of health issues, most notably laminitis and colic.
    • If horses aren’t provided with large amounts of forage throughout the day, it can have psychological effects in addition to physical ones. Without the ability to perform this natural behavior, horses can become bored and frustrated, greatly affecting their well-being.
    • A horse’s digestive tract is delicate, and quick changes in diet, or diets high in concentrate and low in hay or forage, can cause GI issues, namely colic. 
    • Horses are unable to vomit, which can have implications for their care. If they eat something poisonous, they will not be able to rid themselves of it through vomiting.

    So now that you have an idea of how a horse’s digestive system functions, let’s look at the specific nutrients that a horse needs to be healthy.

    What Does A Horse Need?

    Horses, like all other animals (human and non-human), require a combination of carbohydrates, fats and proteins, as well as minerals, vitamins and water. Of course, these needs vary by age, health, and pregnancy-related changes.

    Carbohydrates (Specifically Fiber)

    It probably doesn’t surprise you that carbohydrates are generally the biggest part of a horse resident’s diet. While carbohydrates can be broken down into fiber or starch and sugars, fiber (hay and grass) is definitely the carbohydrate horses need in a greater quantity. Beneficial microorganisms in a horse’s hindgut are able to break down all that structural fiber and turn it into an excellent source of energy.


    Proteins are important as they provide both essential and nonessential amino acids. Horses, in particular, require the essential amino acid lysine. How much of these amino acids an individual horse needs depends largely on their age and whether they are pregnant or lactating. A healthy neutered or spayed adult requires less protein (and corresponding amino acids) than growing, pregnant, or lactating individuals. In fact, while protein is an important part of their diet, if they have too much protein, it will be broken down by the kidneys and expelled as urea in their urine. Unfortunately, this turns to ammonia quickly, which can cause respiratory issues for any residents that have to reside temporarily in a small, enclosed living space.

    In general, a healthy adult horse that is not super energetic and active will need between 8-12 percent protein, depending on how active they are. Growing, pregnant, or lactating horses require higher amounts, between 12-18 percent! Remember this while considering concentrates that will help meet dietary needs: Hay and grass also contains protein! Legume hays, such as alfalfa and clover, are generally higher in protein than grass hay, such as timothy or bermudagrass. It is important to recognize that forage is also a source of protein. Good quality legume hay can have roughly 18-22 percent crude protein, while good quality grass hay can have 10-16 percent crude protein. Quality and growth stage at harvest determine how digestible the hay is and influence how much protein the horse receives from it.


    Horses don’t require much fat in their diet, though a lactating horse may have slightly higher requirements. Did you know that horses don’t have gallbladders? This means it is difficult for them to digest large amounts of fats. In general, 3-4 percent fat in food is a good amount of fat for horse residents. Too much more can lead to unnecessary weight gain and potentially cause health issues.


    While horses actually produce some of the vitamins they need during the digestive process (vitamins B and K), most others are accessible in green, leafy forage. However, if they don’t have access to a lot of quality forage, or if they have particular health issues or they are extremely stressed, they may benefit from supplementation of these vitamins. It is best to discuss whether a resident would benefit from any vitamin supplementation with your equine veterinarian.

    As long as residents have access to the outdoors where they can soak up the sun, their vitamin D needs are usually met. Forage also contains some amounts of vitamin D.  Horses get vitamin A from eating fresh grass and good-quality hay. Any that is not used immediately is stored in the horse’s liver, and this supply is drawn upon during the winter months when pastures are dormant. Horses on a normal diet usually have adequate supplies of all the B complex substances and vitamin K. As for vitamin C, horses can produce this in their liver from glucose. Vitamin E is also found in grass and fresher hay. Alfalfa is a better source of Vitamin E than grass.

    In addition to fresh forage, hay that isn’t stored for more than a few months can retain and provide many of the vitamins horses need. A lot of concentrated grain products provide these necessary vitamins as well. However, they should never make up the majority of a horse’s diet, as this will result in serious health issues. There are also “balancer” pellets that have these vitamins but with a lower calorie content if a veterinarian or equine nutritionist advises supplementing a resident’s diet while not contributing to weight gain.


    There are many minerals that can be beneficial for a horse, but there are three that are of particular importance: calcium, phosphorus, and salt. Also of particular importance are potassium, magnesium, and sulfur. These are considered major minerals.

    There are other important minerals for horses, but they are needed in much smaller amounts and are referred to as trace minerals. The trace minerals necessary for horse health include zinc, copper, manganese, iron, selenium, iodine and cobalt. While mineral blocks provide salt in the diet, the trace minerals are often not received in the necessary amounts because horses only consume so much from the mineral blocks due to the high salt content.

    Mineral amounts and ratios are important things to consider when developing a diet plan for a horse resident. Once again, age and reproductive status can affect the mineral ratios required by an individual. The minimum ratio for a non-pregnant adult horse is 1:1 (that is, all minerals in equal proportion). Individuals require more minerals during periods of growth and pregnancy.

    To consider whether your horse residents are receiving enough minerals, first determine how much hay and grain your horse eats, and read the bag label for the analysis of any grain you may be feeding a resident. Like vitamins, horses can get minerals from their forage. However, depending on the forage, it can be inadequate. The best route to ensuring residents are able to obtain all the minerals they need is to have the forage they consume tested for nutritional content. Then you can better determine what minerals may be lacking from your residents’ diets. Based on those findings, you can discuss with your veterinarian or equine nutritionist the best supplement to purchase that most closely meets the needs of your residents. 


    Horses also need continuous access to clean water. Water is an important part of keeping resident horses healthy. It is vital to their digestive health to drink lots of fluids, and serious complications can arise when their needs for water aren’t met. It is advisable to have water heaters during freezing temperatures, as it allows continuous access to water and also encourages them to drink more. Horses generally will not drink as much if the water is very cold. This can cause a number of health issues.

    Let’s Talk Forage 

    Forage provides nutrients all horses require, making it the foundation of any horse’s diet. Forage promotes a healthy digestive tract and a good gut flora balance. Additionally, it helps meet a horse resident’s behavioral need to forage, and can help prevent boredom and harmful redirected behaviors. For these reasons, horse residents should always have access to ample forage. It is generally recommended that a horse consume 1.5-2.5 percent of their own body weight in forage daily. Of course, forage varies in quality, so it is important to have pasture and proffered forage tested to ensure it provides all the necessary nutrients for residents. Forage that is lacking in certain nutrients can be supplemented with small amounts of properly fortified grains and concentrates. In this case, seek the help of an equine nutritionist or veterinarian to ensure a well-balanced diet for residents. 

    Because of the importance of structural carbohydrates (forage) in a horse’s diet, it is important that the quality of the carbohydrates (forage) be monitored closely. Dusty and moldy hay isn’t a good choice. Ideally, a good quality hay is one that has been cut at the right stage and right length. Low quality hay that is too “stemmy” or even too fine can cause digestive issues such as impactions. Hay that is cut too late has lost most of its nutritional value, as it has an increase in lignin (the thing that makes stems tougher), which can’t be digested.

    Tips For Assessing Hay Quality

    The following considerations should help you generally evaluate hay:

    • It should have a nice green coloring
    • It should have a low moisture content, between 12-18 percent
    • It was cut before fully maturing
      • In the case of alfalfa, this means cutting while it is in early bloom
      • Grass hay should be cut before seed pods mature
    • It smells sweet and fresh, like cut grass
    • It doesn’t contain any poisonous plants, weeds, blister beetles or inedible objects
    •  It isn’t dusty or moldy

    Signs Of Concern With Hay
    If hay is damp, yellow, brown or gray or black, musty smelling, full of weeds or poisonous plants or inedible objects, or has fully matured hay seeds, and in the case of alfalfa, was cut later in bloom, then stay away from it! Do not feed it to residents!

    Types Of Forage

    There are two main types of forage for horses: grass and legumes. In the grass family, there are a variety of species.

    Grass forage

    Grass Forage can be further broken down into cool season and warm season grasses. Timothy (often favored as a very palatable option), orchard, bluegrass, wheat grass, ryegrass, and fescue are all examples of cool season grasses. Horses generally tend to prefer these over warm season grasses, but most horses will accept warm season grasses, particularly if they’re accustomed to them. Examples of warm season grasses include bermuda, pangola, teff, and brome grass.

    In addition to cold season and warm season grasses, there is another category: cereal hays, consisting of grains, leaves, and stems of wheat, barley, and oat plants. While the breakdown of each individual type of grass is more than can be contained in this resource, this gives you an introduction to the depth of the world of forage for horses.


    Legumes make up the other main type of forage for horses. These consist of alfalfa and clover. Legumes are higher in protein and calcium but lower in fiber, particularly digestible fiber. These are often considered palatable options, and alfalfa may be used to encourage horses to eat.

    Many caregivers choose to provide mixed forage, consisting of both legumes and grass hays. There are a number of variables that go into choosing the right forage for your residents, particularly individuals. It is important to speak with your veterinarian or equine nutritionist about the best forage options for each resident, as the type of forage provided can impact weight gain, underlying or known health issues, and promote growth.


    If you aren’t lucky enough to have pastures that produce forage with the right amount of nutrients, you may need to supplement a resident’s diet with grain, supplement being the key word. Diets should still primarily consist of forage, with the level of supplementation necessary discussed with your equine veterinarian or nutritionist.

    Other reasons you might use concentrates or grain mixtures may include:

    • Foals who are growing
    • Some senior horses
    • Hard keepers (horses who have difficulty keeping weight on)
    • Pregnant or lactating mares
    • New residents that are underweight and malnourished
    • For encouraging horses who are not eating or are recovering from certain illnesses

    Each of these possibilities should involve a conversation with an equine veterinarian or nutritionist, as the type, ratio, and amount of concentrates can cause more harm than good if fed improperly.

    Types Of Concentrates

    The grains barley, wheat, oats, and/or corn are considered concentrates, and are low in fiber but higher in energy. Each has its own unique properties which can affect whether it is suitable or unsuitable for individual horses. Oats are usually a preferred food over barley and corn, as it is lighter and bulkier, and less likely to contribute to colic. Corn is very energy-dense, and is usually only fed if a horse has a high energy requirement. There are also “complete” commercial foods that come in pellet form and contain a mix of grains and high fiber or forage components.

    Other grains or concentrates include milo, soybean meal, molasses, and beet pulp. Each one of these has a different nutritional makeup and purpose for feeding to horses. Some grains are considered heavier foods, such as milo and barley. Certain manufacturing processes, such as rolling or grinding and combining these grains with other bulkier and lighter grains can make these a safer choice.

    Molasses is well-liked among horses, and its benefits include being a cheaper source of energy, and its tackiness reduces grain dust in the food. Of course, it isn’t the healthiest option in many cases, and veterinarians or nutritionists may advise against it except for individual cases.

    As illustrated above, there are many concentrates, and whether or not they are beneficial to individual residents depends on a number of factors (age, pregnancy status, availability of quality forage, and health).

    While a detailed breakdown of the individual qualities of each concentrate and forage is beyond the scope of this resource, we hope it provides a useful introduction and reveals some of the complexity that goes into providing the necessary nutrients for equine residents. For this reason, we encourage you to talk with your equine veterinarian or nutritionist to develop appropriate individual diet plans for each horse resident in your care.

    Concentrates And Colic
    There is a correlation between diets high in concentrates and gastric ulcers, wood chewing/cribbing, colic, and laminitis. This can be especially so if these meals are offered in 1 or 2 large meals a day instead of spread out between 4-6 meals. Therefore, care must be taken when providing concentrates as part of a resident’s diet.

    Horse Feeding Guidelines Every Caregiver Should Know

    This resource has a lot of information to take in, and it can be difficult to know how to apply it in a practical way. In this section we have compiled some important guidelines that will help get you started.

    Calculate Need

    Every horse is different, and a variety of factors can influence how much forage is consumed, how much additional hay should be given, and how much, if any, concentrates should be a part of an individual’s diet. Factors to consider include:

    • Activity level
    • Age
    • Pregnancy status
    • Health conditions
    • Are they a Hard/Average/Easy keeper?
    • Nutritional value of forage
    • Access to high quality forage
    • Daily time spent in pasture (assuming there is forage in the pasture)

    Estimate A Horse’s Weight

    Most sanctuaries don’t have easy access to a scale, so obtaining an accurate weight can be a challenge. Weight tapes are easiest but the least accurate way to measure a resident’s weight. A better way is by using a formula.

    Graphic for estimating a horse's weight. Shows where to measure a horse's length (top of shoulder to their tail), and girth (end of their neck to right behind their leg all the way around), along with an equation, reproduced in the resource.

    Step 1: By measuring the “heart” girth (making a loop of measuring tape all the way around) and the body length (from shoulder point to tail) and plugging these numbers into the following formula, you can get a better estimate of their approximate weight.

    Weight (kg) = ( Girth (cm)² x Length (cm) ) / 11877

    (Then multiply the result by 2.2 to get the estimate in lb, if needed.)

    Step 2: Based on the estimated weight (assuming this is an average healthy adult horse), you can estimate how much forage they require each day. In this case, we will say this healthy adult horse with a normal activity level weighs 1,000 lbs. Given that horses should generally consume 1.5-2 percent of their body weight (though this can vary based on other factors), the amount of forage for this individual would be between 15 and 20 pounds. If the forage is nutrient rich, then that horse may be able to obtain all the nutrients they need in a single day from forage. 

    Test Pasture Forage And Hay

    This is important as it allows you to determine the nutritional value and deficiencies in the forage being offered to residents. You can then determine (with the help of an equine veterinarian or nutritionist) what concentrates and supplements and how much of these should be added to a resident’s diet. We will address advanced topics in forage in another resource, as everything from bale size and whether it is a first or second cutting, to species of grass or legume and the amount of rain can all affect the quality of forage.

    Account For Different Populations

    We will be covering special considerations for growing, senior, pregnant and lactating, sick, and underweight and malnourished residents in another resource. Ponies and miniature horses will also require special consideration. Each of these groups will require a look into the nutritional requirements for their particular needs, as they will vary greatly from an average healthy adult horse. 

    Make Changes Gradually

    Sudden changes in diet can lead to serious health issues, such as colic and laminitis. Care should be taken to make changes as gradually as possible to ensure a healthy gut and a happy horse.

    Develop Diet Plans With An Equine Veterinarian Or Nutritionist

    There are many factors to consider when ascertaining the dietary needs of an individual horse. An experienced veterinarian or equine nutritionist will be able to guide your choices and recommend certain dietary guidelines for individuals based on the factors present for that horse. 

    Feed Concentrates By Weight, Not Volume

    If a resident requires concentrates as part of their diet, it is important to initially weigh the amount of different concentrates in the scoop that will be assigned for feeding horse residents. To ensure you are getting an accurate amount of concentrates to feed, fill the designated scoop and weigh it, then subtract the weight of the empty scoop from the total weight. The reason this is so important is because different concentrates take up more or less space depending on their bulk. For example, one pound of half-inch pellets fills a quart scoop, but beet pulp fills a quart scoop while weighing less than half a pound. That is a big difference! You can see how measuring by volume could cause issues and affect the amount of specific food a resident receives.

    Appropriate Treats For Horses

    Treats can be an enriching (and yummy) experience for residents. Below is a list of safe treats and another list of foods to avoid. Remember: These are treats, and should be given sparingly! Too much of a new food at once can lead to an unbalanced digestive tract and cause health issues like colic. The more sugar a treat contains, the more sparingly it should be given. Additionally, some horses are more likely to chew and savor the flavors, while others will inhale treats, making them a potential choking hazard. To avoid this, you can cut treats up into small pieces before offering them. 

    Safe Treats For Horses (in SMALL amounts):

    • Apples (best to remove the core)
    • Carrots
    • Raisins
    • Grapes
    • Bananas
    • Strawberries
    • Melon
    • Celery
    • Pumpkin 
    • Snow peas
    • Green beans
    • Squash
    • Watermelon
    • Peppermints 
    • Sugar cubes 
    • Commercial treats 

    Do NOT Feed Horses The Following:

    • Avocado 
    • Chocolate
    • Kale
    • Onions
    • Potatoes
    • Tomatoes
    • Cabbage
    • Brussels sprouts
    • Alcohol
    • Bread
    • Caffeine
    • Grass cuttings
    • Any food that tends to make them gassy 
    • Any food from the nightshade family

    For a bigger list of things toxic to horses, check out our resource here.

    Suggestions For Food Storage

    In addition to feeding a high quality food, you must be sure to store the food properly to ensure your residents reap all the nutritional benefits. Food will keep best if kept in a cool, dry, dark place. All food, including unopened bags, should be stored in tightly sealed metal cans or thick plastic bins to prevent rodents from getting into food. You can contact the supplier to determine their food’s recommended shelf life, but in general, properly stored bagged food will last about 3 months. Storing food too long or in undesirable conditions can not only lead to rancid or moldy food, but can also cause food to become depleted of vitamins and minerals. Be aware that you should never feed rancid or moldy food to horses, as it can make them very sick.

    As you can see, there are many considerations when it comes to the daily needs and preferences of horses. Don’t get too stressed though! Stick with these basics, converse with your veterinarian or nutritionist, and get to know the individual residents within your care. These steps will start you on the path of healthy, happy residents. Stay tuned for advanced topics in equine nutrition!


    Horse Nutrition: What You Need To Know | University Of California (Non-Compassionate Source)

    An Overview Of Equine Feeds And Supplements | EquiMed (Non-Compassionate) 

    Nutrients Required By Horses | National Cooperative Extension  (Non-Compassionate Source)

    Forages: The Foundation for Equine Gastrointestinal Health | Kentucky Equine Research (Non-Compassionate Source)

    Grains For Horses And Their Characteristics | National Cooperative Extension Resource | (Non-Compassionate Source) 

    Advances in Equine Nutrition Volume-IV | Kentucky Equine Research (Non-Compassionate Source)

    Vitamins For Horses | Kentucky Equine Research (Non-Compassionate Source)

    Minerals: Important For Quality Horse Nutrition | Texas A & M Veterinary Medicine and Biological Sciences (Non-Compassionate Source)

    Non-Compassionate Source?
    If a source includes the (Non-Compassionate Source) tag, it means that we do not endorse that particular source’s views about animals, even if some of their insights are valuable from a care perspective. See a more detailed explanation here.

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