Horses

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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.

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.

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 horses 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.

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.

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

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

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.

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.

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.

Every horses 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)

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.

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. 

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.

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. 

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.

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

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!