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What You Need To Know About Horse Hay


Adapted from eXtension HorseQuest Articles and News and My Horse University Horse Nutrition Online Course


  • Dennis Cash, Montana State University

  • Ashley Griffin, University of Kentucky

  • Jennifer Nadeau, University of Connecticut

  • Christine Skelly, Michigan State University

In this issue:

  • Choose the Right Hay for Your Horses

  • Evaluating Horse Hay

  • Hay Analysis: Its Importance and Interpretations


Choosing the right hay is important for the nutritional health of your horse. Compared to other nonruminant animals, the horse has a relatively small stomach, normal-sized small intestine and a large hind gut. This digestive arrangement makes the horse better suited to grazing continuously than to having one or two large meals a day. You invest a lot of care and appreciation in your horses, so it is wise to spend some time considering their primary diet -- forages.

Diagram of a horse's digestive tract

Left View of the Equine Digestive Anatomy

The horse evolved over time to be efficient as a grazing animal thriving on forages. As we adapted the horse for colder climates, the horse was well-suited to thrive on hay and other conserved forages. Many pleasure horses on small acreages subsist on hay 365 days a year, and their only involvement with "pasture" is a place to exercise.

Traingle representing the feed pyramid of horses

(Right) Forage should be the foundation of the horse’s diet. If necessary, a concentrate (grain mix) may be used to balance for energy and other nutrients required by the horse based on the horse’s classification and type of forage fed. Supplementation above forage and concentrates should only be done if the forage and concentrate portion of the ration still needs to be balanced to meet the vitamin, mineral and protein requirement of the horse. All horses should be provided with clean fresh water and a trace mineral salt block.

What are the principles of feeding hay to horses? Entire textbooks are written on this topic, but the basics are:

  • Hay and other roughages provide nutrients and satiety for your horse.

  • On average, a horse must consume about two percent of dry matter of its bodyweight per day (A 1000 lb horse will need to consume 20 lbs of feed on a dry matter basis).

  • Different ages, classes and workloads of horses require different levels of nutrients from hay.

  • All hay is not the same.

How should you choose hay? The nutrient needs for your horse can be met in a number of ways. For example, if you have late-maturity grass hay, no matter if it is timothy, burmudagrass, orchardgrass, or bromegrass, it will be deficient in protein. You can supply protein and energy in the form of concentrate, which can be grain or a processed feed. Problems with this diet include low forage intake - the late maturity grass hay is consumed at a low level, and horses may develop colic or other disorders from consuming high levels of high-starch grains. At the other extreme, full access to early bloom alfalfa hay can lead to weight problems in lightly-used pleasure horses, due to the high intake potential of the alfalfa. In both of these examples, it may be difficult to meet the horse's daily nutrient demands consistently, and behavioral problems associated with boredom can occur. The compromise for many U.S. horses is a good quality grass-alfalfa mix hay. Some common forage species fed as hay to horses include the following:

Timothy Hay

Timothy hay

Timothy hay is one of the most popular hays fed to horses. It can be quite expensive, depending on whether it has to be shipped long distances. Timothy must be harvested in the pre- or early-bloom stage to ensure a high nutrient content. The first cutting usually has a higher weed content, and quality decreases after the second cutting, so the second cutting is usually the best to feed.

Other cool grass hays with similar nutritional characteristics are orchardgrass and bromegrass which is predominate in the north central United States. (Right: Timothy Hay)


Bermudagrass Hay

Bermudagrass hay is used mostly in the southern United States. Common bermudagrass does not grow tall enough for hay production, but coastal bermudagrass can be used. The same strand of grass can be cut four or five times a year. It is as nutritious as timothy hay, and its value can be increased by growing it with a legume. (Left: Bermudagrass Hay).

Oat Hay

Oat hay

Oat hay is an excellent feed for horses. The choice between alfalfa and oat hay depends on price per unit of energy or protein and the type of horse being fed. Depending on the area of the country in which it is grown, oat hay can be low in protein and contain only marginal calcium, phosphorus, and carotene. (Right: Oat hay)

Alfalfa hay

Alfalfa Hay

Alfalfa hay is one of the best legume hays fed to horses. Legumes are higher in protein, energy, calcium, and vitamin A than grass hay. Most horses will readily consume alfalfa hay. However, because of its high palatability, intake must be restricted to keep horses from overeating and becoming colicky. Alfalfa hay has 120 percent more energy per unit in weight than oat hay. Therefore, it takes less hay to meet a horse's nutrient needs when feeding alfalfa hay. However, the high-energy content may lead to overfeeding and to a fat horse. If cured correctly, vitamin C content will be high. The calcium:phosphorus ratio is about 6:1 and must be considered when feeding young, growing horses. A mixture of legume and grass plants is the best type of hay to use for some horses or geographical areas. (Left: Alfalfa hay)

Clover and Grass Hay

Red clover

Clover hays are similar to alfalfa hays because they are legumes. Clover hay is usually mixed with grass hays. There are five kinds of clover hay: red, common white, crimson, alsike, and landino. White and landino clovers are usually grown for pasture. The other three contain 14 to 16 percent crude protein. Red clover causes "slobbers" in horses. Slobbers is excessive salivation that does not hurt the horse. (Right: Red clover)


Any of the common hays discussed above can be fed to horses, but what's most important is nutrient value in relation to the cost of the hay. A good understanding of the factors that affect hay production and what to look for when buying hay will help you select high quality hay that meets your horse’s nutritional needs.

To evaluate the quality of hay, the following questions should be considered:

1. At what stage was the hay harvested?

Nutrient value largely depends on the age at which the hay was harvested. Early maturity hay is very leafy and has a high nutrient density and palatability. Late maturity hay contains coarse, thick stems and fewer leaves than early maturity hay. As plants mature and reach the reproductive stage of development, their protein content, digestibility, and palatability decline. The ratio of stem to leaf increases with maturity, so the plant has a higher fiber content. Maximum nutrient content can be obtained by harvesting legumes when a few flowers start to appear. Grasses are harvested when the seed heads begin to appear, and grain hays when the grain is in the soft-dough stage.

Hay type should be matched to the horse type. Early maturity hay would be perfect for growing horses and lactating mares, but it may not be the best choice for horses with low nutrient requirements. Mid- to late-maturity hays are best for horses with low nutrient requirements, because the horses can eat more to satisfy their appetites without overeating and becoming fat.

Horse owners also ask whether first or second-cut hay is better. There is more variation within a cutting than between cuttings. First-cut hay is often discriminated against for several reasons -- rain damage or rain delays make hay harvest occur at advanced maturity, and there may be more weeds present. One problem with late first-cut mixed hays is course steminess of both alfalfa and grasses, resulting in reduced intake of the grass. Second-cutting hay can generally be put up without rain delays.

Person analyzing hay quality

However, overly-mature second-cut hay can still be less palatable and nutritious. The best bet is to view the hay, see its condition and ask for a hay analysis. Any of the common hays discussed above can be fed to horses, but what's most important is nutrient value in relation to the cost of the hay. A good understanding of the factors that affect hay production and what to look for when buying hay will help you select high quality hay that meets your horse’s nutritional needs.

Visually inspecting hay for texture, cleanliness and odor will help determine overall quality and suitability. Source: Photo courtesy of USDA Natural Resources Conservation Service. (Image right)

2. How many leaves and stems are present?

Harvesting procedures can affect the leaf content. Excessive movement of the hay during the drying process can shatter the leaves. Overdried hay will lose its leaves when baled. Stem content is related to the age at which the plant was harvested. The ratio of stem to leaf increases as age increases so that the hay has a higher fiber content.

In addition, rainfall at the proper time during the growing season will affect hay quality. Drought conditions result in stunted growth and fewer leaves. Excessive moisture often leads to diseases that decrease leaf production.

Comparison between alfalfa leaves and grass leaves

Alfalfa leaves are on the left and grass leaves are shown on the right. (Image left)

Hoary alyssum

3. Is the hay free of dust, mold, and weeds?

Clean hay is the best hay for horses. Mold and dust can inflame the respiratory tract and impair breathing. Many horses can develop permanent lung damage after consuming moldy or dusty hay. Heaves is a common respiratory problem that occurs when a horse consumes moldy or dusty hay. Mold can also cause digestive upsets in the horse. Weeds are undesirable in hays because they are low in digestibility and acceptability by the horse. In some cases they may also be poisonous. Many times, hay will not be consumed by the horse if weeds are present.

Hoary alyssum is a weed that is toxic to horses and is most common in Midwestern fields. (Image right) Source: Catherine Herms, Ohio State University / OARDC,

For more information on Hoary alyssum, read the Michigan State University Extension bulletin Identification, Livestock Toxicity and Control of Hoary Alyssum in Christmas Tree Plantations and Forages (E2978).

4. Is the hay free of insects?

Blister beetle

Alfalfa hay may be infected with blister beetles. When a horse eats a blister beetle, a chemical in the beetle causes colic, fever, and eventually death. Historically, blister beetles have been most abundant in arid regions of the U.S. where grasshoppers are abundant almost every year. Unfortunately, there is no sampling method that can detect toxic levels of blister beetles in cured hay.

For more information on blister beetles and how to prevent blister-beetle toxicity, go to the University of Kentucky Entomology web site.

There are many varieties of blister beetles. The toxicity level of this beetle is dependent on the species and sex, with striped male beetles being the most toxic. (Image left)

Source: Clemson University - USDA Cooperative Extension Slide Series,

5. Is the hay weathered?

Tractor in a field cutting hay

Weather conditions affect field-cured hay--hay that is left out in the field to dry after it has been cut. Rain and excessive sunlight reduce the quality of hay by reducing the nutrient content. Rain beats the leaves from legumes, leaches out soluble carbohydrates, and packs the hay so it doesn't dry properly. If hay is baled when it is too moist, it will become moldy and have a musty, moldy odor. Excessive sunlight will bleach the color of the leaves and causes a loss of vitamin A. If hay is cured too slowly, hay will ferment and lose its nutrient content. The ideal moisture content of hay when it is baled is 12 to 18 percent moisture. Excessive moisture due to rain can cause the hay to mold when it is baled or processed.

Dry weather is critical for harvesting quality hay. Cutting the hay is the first step in harvesting. (Image right) Source: Photo courtesy of USDA Natural Resources Conservation Service.


Having your hay analyzed is a great idea. It is the only way to determine the actual nutrient content of the hay. It is important to know this so that you can be sure your horse is consuming an adequate diet. You may or may not need to feed grain, depending on the quality of your hay. The better the quality of the hay you feed, the less grain you will need to feed. This can be a significant savings.

In order to have your hay analyzed chemically, you will need to get a hay sample. Use a core sampler and try to sample from at least 20 to 25 different bales. Be sure to penetrate into the center of the bale with the core sampler. If you do not have experience in hay sampling, see your county extension office for information on how to use the core sampler or to borrow one. Mix the samples together and then put them in a tight, clean, plastic bag or the bags that the forage testing lab provides. Mail the bag to the forage testing lab as soon as possible and have it analyzed.

A representative hay sample must be taken with a hay probe on a variety of bales in a hay lot. (Image left) For more information on hay analysis, visit Equi-analytical Laboratories.

Interpreting Hay Analysis Results

Interpreting your hay analysis results may not be the easiest part of this process. If you cannot determine what the results mean, you may want to consult an extension specialist in forage crops or agronomy at your county extension center, an animal scientist or a county extension agent. Some of the main things to focus on when you see the analysis reports are:

  • Dry Matter (DM)– This tells you how much of the sample is left after water is removed. It is the moisture or dry matter content of the sample. Hay will generally be about 89 percent dry matter or greater.

  • Digestible energy (DE) – This is a measure of the digestible energy in the hay. For a light-working horse, DE should be 20.5 Mcal/day. Hay may have .76 to .94 Mcal/pounds or higher of DE.

  • Total Digestible Nutrients (TDN) - This is a measure of the total digestible nutrients in the hay or its energy value. TDN may be used in place of DE or offered in addition to DE. It may range from 40 to 55 percent.

  • Crude Protein (CP)– This is a measure of the protein concentration of the hay and can range from 6 percent to 8 percent in native grass hays to about 15 percent or higher in high quality legume hays.

  • Neutral Detergent Fiber (NDF) – This is a measure of the plant’s cell wall content, shown as a percent. The higher this is, the less hay the horse will eat.

  • Acid Detergent Fiber (ADF) – This is a measure of the fiber concentration of the hay, shown as a percent. As ADF increases, digestibility and nutrient availability decreases.

  • Non-Structural Carbohydrates (NSC) – This is a measure of the non-structural carbohydrates in the feed. If your horse has Cushing’s disease or is prone to colic or laminitis, you want to select hay with a lower NSC value. Timothy and alfalfa hay may have a 15 percent or 20 percent NSC value, respectively. If you want this analysis done, you should check to see if the lab offers it, as it is not a common analysis at this time.

  • Starch and Sugar- This is a measure of sugars and starches in the feed. You should feed no more than 15 percent of total daily calories from starch and sugar to horses with EPSM (equine polysaccharide storage myopathy) and PSSM (polysaccharide storage myopathy). EPSM is a muscle disease found in over 100 draft breeds that may cause severe weakness and muscle wasting in horses of all ages, poor performance, abnormal hind limb gaits and shivers, in which the muscles keep twitching. PSSM is a muscle disease found in horses with Quarter Horse in their breeding, such as American Quarter Horses, Paints and Appaloosas. Symptoms include reluctance to move, muscle stiffness, sweating, shifting lameness and tremors in the flank area.

Now you know some basics about analyzing hay. Be sure to consult your county extension agents or state specialists for help if you are not sure how to apply these results. By analyzing your hay, you will be able to feed your horse more effectively and efficiently.

NIRS machine

Near Infrared Spectroanalysis (NIRS) used for feed analysis.

Forms of Hay

Hay comes in several forms—baled, wafered (also referred to as cubed), and pelleted. Baled hay is the most commonly used. It is usually less expensive than processed hay. Long stem roughage is also best for gut motility. Small hay bales with an average weight of 50 lbs. are usually bought for horse hay. Small bales are easy to move manually and can be stored easily.

Small square bales are commonly fed to horses. A bale may range in weight between 40 – 75 lbs.

Round bales weigh an average of 1000 lbs. and require special equipment for movement. Round bales must be stored under cover to prevent loss from mold. In addition, round bales need to be fed to groups of horses (seven to ten can eat the bale in three to four days’ time). To decrease waste loss, round bales should be fed in round bale feeders designed for horses. Round bales are usually cheaper per pound to purchase and can save on feed labor and costs if they are managed to limit hay waste.

Round bales should be fed in feeders specifically designed for horses to decrease wastage and ensure the horse's safety.

There may be times when baled hay is hard to locate or not practical to feed. Hay cubes (wafered hay) or hay pellets can decrease hay waste and provide the needed roughage in a horse’s diet. However, horses will tend to eat processed hay faster, particularly when it is in pelleted form. Processed hay is sold by the type of forage processed. Hay cubes and pellets are available in alfalfa, grass, or alfalfa/grass mixes.

A well-made cubed hay is easy to chew and should not need to be broken to avoid choking, if your are feeding healthy horses with good dental hygiene. Pelleted hay, while providing the needed fiber for the diet, is eaten more quickly than baled hay; and thus a horse may become bored and be more prone to wood chewing or other abnormal behaviors. In times of hay shortages, it is best if hay is rationed out and extended with supplemental hay pellets to ensure there is some long-stem roughage for gut stimulation.

Alfalfa pellets are on the left and alfalfa cubes are shown on the right. Hay pellets provide dietary fiber, but are consumed much faster than long stemmed forage.

Purchasing Hay

Get to know your hay producer and stick with a good one. Some commercial producers will provide a hay analysis and bale weights.

Round bales stacked for sale

Hay in small rectangular bales sells more per ton than large round or square bales, because the hay producer goes through the effort of handling, stacking, covering (many do), hauling and dealing with small lots of hay and many diverse customers. Good hay buyer-seller relationships will provide trust, respect, prompt payments and consistent hay supplies. Once the hay is home, place it under a shed or tarp it to preserve its quality.

Purchasing a year’s supply of hay at one time will reduce shipping and labor costs, allow the owner to buy when prices are lowest, and supply a more consistent forage year round.

Hay Storage

Hay should be put under a roof to avoid exposure to sun and rain, but the area should also have good ventilation to reduce the occurrence of mold. The bottom row of hay should be raised off the ground with boards or pallets to allow for air circulation and to ensure the hay stays dry. Similarly, hay stacked below/slightly away from ridge vents allow for upper ventilation. Hay will lose nutritional value the longer it is stored. However, hay can be fed the second year after it is cut as long as it is dry and free from mold. The lower the moisture content the longer it can be stored with less chance of mold and spoilage. Less than 20% moisture content is desirable.

Hay being stored in an open barn

It is common to store hay in a loft over the stabling area of the horses. However, a mass of hay can reduce air ventilation in the barn environment if it inhibits peak ventilation of the barn roof. In addition, large quantities of hay stored in the stabling area are a fire hazard. Dry hay is not only highly combustible, but hay stored wet can also build heat through fermentation and spontaneously catch fire. Many insurance companies will give farms rate reductions if hay is stored in a separate building.

Hay should be stored under a roof and raised off the ground to ensure that the hay stays dry. (Image right).

Additional Resources

Griffin, Ashley. Factors that Affect Hay Quality. (2009). eXtension HorseQuest Article.

Griffin, Ashley. Hays for Horses and Their Characteristics. (2009). eXtension HorseQuest Article.

Griffin, Ashley. Selecting Horse Hay. (2010). eXtension HorseQuest Article.

Horse Hay Publications. eXtension HorseQuest Article.

Martinson, K. and P. Peterson. Selecting and Storing Horse Hay. (2007). University of Minnesota Fact Sheet.

Nadeau, Jenifer. Hay Analysis: Its Importance and Interpretation. (2011) . eXtension HorseQuest Article.

National Research Council. Nutrient Requirements of Horses. (1989). National Academy Press, Washington, D.C.

Wright, Bob W. Hay. Haylage and Treated Hay for Horses. (Sept. 2004) Online fact sheet. Ontario Ministry of Agriculture and Food.

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