Horses are herbivores; therefore, they can consume a predominately forage diet. The equine species have a large colon and cecum which contain bacteria that enable them to digest forage. In fact, in situations when stress is minimal, mature horses can do well on pasture or hay alone without added grain.

The availability of good quality forage is very important to keeping horses healthy. Poor quality hay or pasture can cause distended digestive tracts (hay bellies) and increased reliance upon supplemental grains. The difference between horses and ruminants is the relatively small size of the stomach in the horse and the four compartments in the ruminant’s stomach.

Working or lactating horses have a limited capacity to consume needed amounts of energy and protein from forage alone necessitating energy supplementation from grains. Regardless of the horse’s nutrient requirements, some forage (approximately 0.5%–1% of body weight) is always required to keep the digestive tract functioning normally.

Good pasture is the most ideal form of forage for a horse. However, quality pasture is becoming increasingly difficult to provide. Approximately half the horse population lives in suburban areas where stored forages must be fed year round. Even horses in rural areas often are not grazed. Consequently, horse owners need to be able to recognize good and poor quality forage.

Hay is the most common forage for horses and can be stored in several different forms. Square bales are common in suburban areas because they are easy to transport and feed to individual horses with minimal waste. Square bales can vary in weight and size depending on the type of legume or grass and the geographical area.

Grass hays can also be baled into round bales. Big round bales are popular because large acreage can be harvested quickly. Free-choice feeding of round bales could be an advantage for horse owners. Round bales are usually less expensive per pound but excessive waste (20%-30%) should be expected. Excessive waste occurs because horses will eat more of the hay than is needed and because round bale hay can be easily trampled. Large round bales, especially those stored outside, are more prone to mold development.

Recognizing High Quality Hay
The price paid for hay should be determined based on the nutrient content (quality), hauling and storage costs. There are many factors that affect the quality and nutrient content of baled hay.

Plant species

Legumes, such as clover and alfalfa are higher in protein, energy, calcium, and vitamin A than grasses. Table 1 shows NRC values for some common hay forages. Quality of legumes will be dependent on growing and harvesting conditions. Some grasses that are cut and baled under optimum conditions will be better quality forage than a legume not harvested under optimum conditions. Many different types of grass and legume hays are specific to certain parts of the country. Prior to purchase or feeding, hay should be analyzed to determine the nutrient content.

Alfalfa is one of the most popular hays fed to horses. In areas where alfalfa is not grown, many horse owners buy alfalfa even if it means transporting long distances. However, its palatability and high energy content can cause some horses to overeat. Alfalfa and clovers are rich in calcium, carotene (vitamin A precursor) and protein, especially if cut in the early to mid-bloom stage. The high calcium content can be a concern in young, growing horses. The second and third cuttings are usually the highest quality; hence, these cuttings are usually more valuable. Dilution of alfalfa with a more bulky hay is necessary for mature horses that are idle or at light to moderate work.

Coastal bermudagrass hay is another popular hay frequently fed to horses in the southern U.S. If fertilized and harvested correctly, coastal bermudagrass can contain up to 16% protein and can provide a good quality forage for all ages of horses and for horses under different work loads. Timothy, a traditional grass hay for horses, is easy to harvest and cure.

Timothy is commonly seeded with clover or alfalfa because timothy is low in protein and calcium when compared to other common forages.

Orchardgrass hay is grown across the northern U.S. and should be harvested in the early-bloom stage to achieve the best nutrient content. The nutrient content is adequate to meet the requirements of horses under minimal nutritional stress, such as non-working horses. This grass can be improved by mixing with alfalfa or clover.

Weeds and Toxins
Horses are more susceptible to toxins and poisonous plants than cattle. Cattle are ruminants with a large fermentation vat in which bacteria break down and detoxify many potentially harmful substances found in plants and weeds. Horses do not have a rumen; consequently, certain toxins are absorbed from the intestinal tract.

Fiddleneck (Amsinkia intermedia), also called tarweed or fireweed, can cause liver cirrhosis. Noticeable symptoms occur after ingesting contaminated hay over time and there is no known treatment. Symptoms include weight loss and incoordination.

Yellow Star Thistle is also toxic to horses after they have consumed a large quantity over several months. Horses acquire a taste for the thistle and will readily eat thistle-contaminated hay. Early symptoms can be discrete with some paralysis in the mouth. There is no treatment and symptoms advance to muscle and nerve damage in the mouth causing inability to eat.

Blister beetles present a major problem predominantly in legumes. The presence of dead beetles and their poisonous fluids in baled hay can create serious problems in horses. Horses are very susceptible to the blister beetle poison cantharidin. Between 10 and 300 blister beetles can produce enough toxin to kill a horse. Small amounts of cantharidin can cause a horse to colic. Blister beetles invade alfalfa predominantly after the first cutting of hay and especially under irrigated conditions. Blister beetle swarms are very hard to avoid if they are already in an area. In some areas of the U.S., it is impossible to obtain locally grown alfalfa hay that is certified “blister beetle free.” Blister beetles are not present in Canada and therefore, forage grown in Canada can be certified “blister beetle free.”

When purchasing hay, high-quality forage should be selected by using these guidelines in the following table

Criteria to Select High-Quality Hay for Horses No mature seed or plants in full bloom should be present. No weeds or poisonous plants. High proportion of leaves to stem. Bright green color. Good clean hay with no moldy, musty or dusty smell. No foreign material present such as sticks, stubble, weeds, dirt, bottles, etc. Nutrient analysis from a reputable laboratory is comparable to published values for high-quality hay of the same species.

Hay Cubes Hay cubes are another method of feeding forage and can be beneficial when good-quality hay is in short supply or as a means of providing a consistent form of high-quality forage. Hay cubes are usually 1.5 or 2 square inch and comprised of alfalfa or alfalfa-grass mix, packed very tightly. Some of the benefits associated with hay cubes include:

• Waste is minimal with cubes and usually there are no palatability problems.

• High-quality cubes produced specifically for horses will be virtually free of dust and mold spores.

• Hay cubes are generally more consistent in nutrient content than hay bales.

• Hay cubes are easy to handle, feed, and store. They are more compact than hay bales.

• Some cubes can be guaranteed blister beetle free.

Hay cubes are more convenient but can be more expensive per pound compared to baled hay. Horses eat hay cubes in less time than the same amount of baled hay. This could lead to boredom if the horse is not exercised regularly.

Summary
While baled hay is the most common form of stored forage for horses, many factors affect its quality. The plant species, growing and harvesting conditions and practices, the stage of growth at cutting, and the presence of weeds or toxins all have a large impact on the quality and acceptability of the hay. Along with a laboratory analysis, hay should be visually appraised before purchase. Hay cubes are another form of stored forage. Good-quality cubes can be advantageous to horses and owners because they provide a consistent high-quality forage with no weeds or toxins, and are easy to handle and feed.

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