Hay is the most underestimated feed in the equine diet — and at the same time the most important. On any property where horses do not have permanent access to quality pasture, hay represents the foundation of their feeding, the direct substitute for fresh grass, and the element that keeps the digestive tract working as nature designed it. Getting the choice, storage, or quantity of hay wrong undermines the entire nutrition program, no matter how many supplements or concentrates are added on top.

What Hay Is and Why It Cannot Be Replaced

Hay is forage that has been cut, dried, and preserved. But that simple definition conceals enormous variation in nutritional value, palatability, and suitability for different horse categories. A poorly cured hay can deliver less than 50% of the nutritional value of an excellent hay made from the same grass — the difference between feeding well and feeding poorly with the same product.

The reason hay cannot be replaced lies in equine digestive physiology. The horse’s large intestine — cecum and colon — houses a dense population of microorganisms that ferment long-stem fiber and produce short-chain fatty acids, an important energy source. Without sufficient forage, that fermentation slows, intestinal pH destabilizes, and gut motility drops — conditions that predispose the horse to impaction colic.

Forage also keeps the horse occupied. A horse grazing or chewing hay produces saliva continuously — up to 9 gallons a day in animals that chew for extended periods. Saliva acts as a buffer in the stomach, neutralizing acid that is produced constantly whether or not the horse is eating. Periods without forage lasting more than 4–6 hours are enough to significantly increase the risk of gastric ulcers.

Types of Hay and Their Characteristics

Tropical and Warm-Season Grasses

The most common hays in hot and humid climates — across much of South America, tropical Asia, and Africa. The most frequently encountered:

Tifton-85 — widely used, good energy-to-fiber ratio, high palatability. Suitable for most horse categories. Cutting at the right stage (before flowering) ensures good protein content (10–12%).

Coast Cross — similar to Tifton, slightly less digestible when cut late. Common on properties with extensive pasture management.

Brachiaria/Urochloa — coarser hay, variable nutritional value. Suitable for horses in maintenance but may be insufficient for growing horses or high-performance animals without supplementation.

Bermudagrass — the international benchmark for competition horses in the United States, extensively researched. High digestibility, good amino acid profile. More common in warm-temperate climates.

Cool-Season Grasses

Timothy — the classic hay for horses in temperate climates (Europe, northern United States, southern South America). Excellent palatability, good energy-protein balance, low laminitis risk. Considered the reference hay for competition horses in many countries.

Tall Fescue — very common in the United States. Important caution: fescue infected with the endophyte fungus (Neotyphodium coenophialum) is toxic to pregnant mares and can cause abortion or foaling complications. Always verify the source.

Orchard Grass — good palatability, reasonable digestibility, widely used in Europe and North America.

Legumes

Alfalfa (lucerne) — the most widely used legume hay for horses in the world. High protein (15–22%), high calcium, excellent digestibility. It is a rich hay — appropriate for growing foals, lactating mares, and high-performance horses, but can be excessive for horses in maintenance or with predisposition to metabolic issues.

Clover — lower protein than alfalfa but still significantly richer than grasses. Can cause photosensitization in light-colored horses if consumed in large quantities.

How to Evaluate Hay Quality

Visual and Sensory Assessment

Color: Quality hay ranges from green to olive-green. Yellow or brown hay indicates late cutting, excessive drying, or rain exposure — loss of vitamins and, in extreme cases, protein.

Smell: Should have the characteristic scent of dry hay — slightly sweet, fresh, agricultural. Any mold, fermentation, or excessive moisture odor signals a preservation problem. Moldy hay should never be fed to horses — the fungi produce mycotoxins that cause respiratory and liver problems.

Texture: Stems should be flexible enough to bend without immediately snapping. Very lignified hay (thick, rigid stems) signals late cutting — low digestibility.

Leaves vs. stems: Most of the nutritional value is in the leaves. Bales with a high proportion of leaves are significantly more nutritious than those dominated by coarse stems.

Unwanted plants: Check for the absence of toxic plants and excessive weeds that reduce palatability.

Laboratory Analysis

For properties with many animals or horses with special needs, laboratory forage analysis is highly recommended. The key parameters include:

  • Crude protein (CP): total protein content
  • Neutral detergent fiber (NDF): the higher it is, the lower the digestibility
  • Acid detergent fiber (ADF): a direct digestibility indicator; above 40% indicates poor-quality hay
  • Digestible energy (DE): calculated from the parameters above
  • Calcium and phosphorus: important to verify the Ca:P ratio

Forage analysis laboratories are available in most countries; the cost of a complete analysis is quickly recouped through better supplementation planning.

How Much Hay to Offer Per Day

The daily amount of hay depends on three main factors: the animal’s body weight, activity level, and hay quality.

General rule: total forage (pasture + hay) should represent between 1.5% and 2.5% of body weight in dry matter per day.

For a 1,100-pound horse:

  • Minimum: 16.5 lbs of dry matter = approximately 18–20 lbs of fresh hay (at 15% moisture)
  • Ideal: 22–26 lbs of dry matter = 24–30 lbs of fresh hay

Horses with access to quality pasture need less supplemental hay. On abundant, nutritious pasture, hay can serve mainly as a supplement during periods of lower grass availability.

Horses in full stabling rely entirely on hay (or haylage). Free-choice hay — with forage available at all times — is the best strategy for maintaining gut health and preventing boredom behaviors (cribbing, stereotypies).

Horses prone to obesity or equine metabolic syndrome need hay controlled in both quantity and energy content (late-cut grasses, low fructan content). For these horses, free-choice feeding is not appropriate.

Storage: How to Preserve Hay Quality

The quality of hay at time of use depends as much on harvest quality as on storage conditions.

Moisture: Hay should be stored at below 20% moisture. Above that, heating from bacterial fermentation occurs, nutritional value is lost, and in extreme cases, spontaneous combustion is possible.

Location: A covered, ventilated building, with elevated flooring (pallets or wooden boards) to prevent contact with ground moisture. Bales stored directly on wet ground lose quality rapidly.

Stacking: Leave space between bales and walls for air circulation. Large round bales stored outdoors need to be covered with tarps.

Time: Well-stored hay maintains its quality for 1 to 2 years. Beyond that, vitamins begin to degrade — especially vitamin A — but fiber and protein value are retained.

Hay vs. Haylage

Haylage (grass silage) is an alternative to dry hay, especially in high-humidity regions where drying is difficult. It has higher moisture content (45–55%), lower dust risk, and good palatability. Horses with respiratory problems (IAD — inflammatory airway disease) often benefit from switching to haylage or soaked hay.

The main disadvantage is management: opened haylage must be consumed within a few days to prevent spoilage. Storage costs (airtight plastic wrapping) are also higher.