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Forage is the single highest volume component in the equine diet. The type, quality, and maturity of the forage you feed have the biggest impact on the nutritional composition of your horse’s ration.
Selecting the right forage to feed your horse helps to ensure that their energy, protein and nutrient requirements are being met while minimizing the risk of metabolic conditions, excess weight gain, gut issues and laminitis.
The only way to accurately assess the quality of forage is to submit a sample for analysis. However, some visual and sensory cues can help you identify forage species and maturity to estimate nutritional quality. These cues will help you choose forage that is appropriate for your horse.
This article will review the importance of appropriate forage in the equine diet and how to identify and inspect hay for horses.
Forage in the Equine Diet
Forage should provide most of the calories and protein in your horse’s diet. [1]
Horses are grazing animals that evolved to thrive on continuous intake of fibrous foodstuffs, such as grass and other forages. [2][7]
To support optimal health, the average horse should consume 2% of its body weight in forage every day. For an 1100 lb (500 kg) horse, this is equivalent to 22 pounds (10 kg) of hay or pasture dry matter per day. [4][13]
Providing your horse with free-choice forage is ideal whenever possible. [1] Ad libitum intake of hay reduces stereotypic behaviours and ensures that the horse’s stomach is not empty for long periods, decreasing the risk of gastric ulcers.
Long-stem forage is the best option, including pasture or hay that is two inches or longer. These forages promote saliva production and slow consumption. [5]
Avoid feeding large amounts of commercial feeds. Diets with too much grain and not enough forage can contribute to digestive problems, metabolic issues and behavioural concerns. [3]
What is Forage?
Equestrians often use the terms hay and forage interchangeably, but forage can refer to any edible plant material aside from grain consumed by grazing animals. [6]
In equine diets, forage includes pasture, hay, haylage, straw, or other high-fibre hay substitutes. These should provide the base of every horse’s nutrition program. [1]
Some key characteristics of common forage sources for horses are:
- Pasture: Fresh pasture is typically higher in energy, protein and other nutrients than hay. Pasture is prone to elevated sugar content, which can increase the risk of metabolic syndrome, obesity, and laminitis. [15]
- Hay: Conserving dry forage reduces levels of vitamins (such as vitamin E) and other nutrients. Nutritional quality is determined by the stage of maturity, species, and conditions during harvest and storage. [12]
- Forage pellets or cubes: Finely chopped hay that is compressed can replace hay when forage availability is limited or for horses with dental issues. These feeds may need to be soaked to reduce the risk of choke.
- Forage substitutes: Certain fibre-rich by-products, such as beet pulp, can be used to replace some of the forage in the diet. Work with an equine nutritionist to ensure the diet is well-balanced to meet your horse’s needs.
Selecting Forage for Your Horse
The best forage for your horse depends on their individual protein, energy, and nutrient requirements. Horses in heavy work have different needs than leisure horses in light exercise.
While horse owners often look for high-quality hay, some horses actually benefit from low-quality forage that is less nutrient dense. [2]
High-Quality Forage
High-quality forage generally refers to hay with a higher nutrient density, including higher levels of protein and energy, with lower levels of indigestible fiber. Horses that may benefit from high quality hay include:
- Growing horses
- Late gestation mares
- Lactating mares
- Underweight or starved horses
- Hard keepers
- Horses in heavy or very heavy work
Mixed hay, legume hay, or grass hay harvested at an earlier stage of growth may be appropriate for these horses. Additional energy sources such as fat supplements, rice bran or beet pulp may also be required to fully meet their energy demands. [17]
Low-Quality Forage
Low-quality forage refers to hay with lower levels of digestible energy and protein and higher levels of indigestible fibre. Horses that may benefit from less nutrition hay include:
- Easy keepers
- Horses with metabolic concerns, such as Equine Metabolic Syndrome
- Overweight horses
- Horses at maintenance or in light to moderate work
- Laminitis-prone horses
These horses would be best served by grass hay harvested at a later stage of maturity when fibre content is higher, and protein content is lower.
Vitamins and Minerals
Regardless of the type of forage, hay alone will not meet all of a horse’s vitamin and mineral needs. [16] Horses on a forage-only diet are often deficient in several of the following nutrients:
- Sodium
- Selenium (depending on geographic region)
- Zinc
- Copper
- Vitamin E (for horses consuming hay)
A balanced vitamin and mineral supplement, such as Mad Barn’s Omniety, will ensure these micronutrients are adequately supplied on a forage-based diet.
Types of Hay for Horses
There are three categories of hays for horses: cool-season grasses, warm-season grasses, and legumes. Each category is associated with a different nutritional profile.
Cool-Season Grasses:
- Cereal forages: oat, rye, wheat, barley
- Orchard grass
- Timothy
- Fescue
- Bluegrass
Warm-Season Grasses:
- Bermudagrass
- Teff
- Bahia
- Switchgrass
- Sorghum
Legumes:
- Alfalfa
- White clover
- Red clover
- Rhizoma peanut
- Birdsfoot Trefoil
- Lespedeza
Identifying Forages
A visual appraisal can help identify the species of forage in your hay and estimate its quality. [11] When growing in the field, grasses and legumes can easily be distinguished by looking at their structures.
Grasses have either round or flat stems, with blades growing off the stem along the entire length. When looking down at the plant, the blades grow in two directions off the stem. [33]
The shape and structure of the seed heads and the height of the plant at a given stage of maturity are the best way to visually distinguish between different grasses. The number of seed heads will vary depending on the plant’s maturity at harvest. [6]
Instead of blades, legumes produce leaves made up of multiple leaflets. These are most abundant at the top of the stem, but some may also appear along the stem. Depending on the species, the leaves may contain three to seven leaflets and may or may not have serrated edges. [33]
Figure 1: General structure of A) grasses and B) legumes
Identifying Legume Species
Alfalfa
Alfalfa is the most popular legume hay fed to horses. Although often characterized as a leafy and vividly green legume with a sweet smell and distinct purple flowers, different harvesting methods and growing conditions can cause variations in appearance. [18]
Alfalfa grows 2 to 3 feet tall. The plant produces purple or yellow flowers and long and narrow leaves that are serrated only at the tip. [19][20]
The highest quality alfalfa will have buds but no blossoms, indicating that the farmer harvested the alfalfa at the ideal stage of maturity. Alfalfa becomes less leafy and more stemmy in the late-bloom stage. [19]
Figure 2: Alfalfa hay with visible leaflets and stalky stems
Clover
Clover is typically grown in mixed fields along with grasses but can also be fed alone. Red clover is the most common type of clover fed to horses.
Red clover grows two to three feet tall. It has large leaves, which often have a prominent V-shaped pattern or watermark on them, produces pink flowers and has hairy and fleshy stems. [19]
White clover (Trifolium repens) produces white, fragrant flowers. It has broad, solid green leaflets, sometimes marked with a white v-shaped pattern or with dark red flecks. [19]
Clover is susceptible to blackpatch disease caused by the fungus S. leguminicola. This produces a toxin called slaframine which can cause slobbers in horses, a generally harmless condition.
Other Legumes
Rhizoma Peanut
This tropical legume is grown in warmer climates, such as the Southeastern US. This plant produces orange to yellow flowers and leaves with four leaflets. This plant has fine stems and forms thick roots four to six inches below the ground surface. [21]
Birdsfoot Trefoil
This legume grows two to three feet tall. Birdsfoot Trefoil produces bright yellow flowers and seed pods that resemble the shape of a bird’s foot. Each leaf of the plant is comprised of five triangular-shaped leaflets and prominent leaflike structures (stipules) on the lower stem. [19]
Annual Lespedeza
Annual Lespedeza grows one to two feet tall. It produces pale green leaves with visible veins and has a fine, leafy stem. [19]
Perennial Lespedeza
This legume grows 18 to 40 inches tall. Perennial Lespedeza has a stiff main stem with leaves extending from it. [19]
Identifying Grass Species
Grass hay is generally higher in fiber and lower in protein than legume hay. The high fiber and moderate protein content make this a popular foundation for equine feeding programs. [22]
Grass hays contain more indigestible fiber in mature stages. [23]
Cool-Season Grasses
Horses generally find cool-season grasses more palatable than warm-season grass hays. [24] These grasses have evolved to survive below-freezing temperatures and winter weather conditions.
Timothy
Timothy grass grows two to five feet tall. This plant produces bluish-green-coloured leaves, has a cylindrical seed head, and a bulb-like structure at the base of its stem. [19]
Figure 3: Timothy hay with visible blades and seedheads
Orchard Grass
Orchard grass produces consistent soft texture hay that horses readily consume. This plant’s leaves are blue-green in color and the stem is nearly flat at its base. It has a tall and thin outgrowth (ligule) at the junction of the leaf and leaf stalk. [19]
Annual Ryegras:
This grass grows two to four feet tall. Annual Ryegrass produces shiny, dark green smooth leaves and has round-shaped stems. Its leaves emerge rolled with small ear-like projections (auricles) that wrap around the stem. Annual ryegrass has fine hairs (awns) that extend from the ends of its seeds. [19]
Perennial Ryegrass
Perennial Ryegrass grows two to four feet tall. This plant produces shiny, dark green, smooth leaves. Unlike annual ryegrass, perennial ryegrass does not have awns and has fewer small flowers (referred to as florets) that comprise larger clusters of flowers. [19]
Oat Grass
Oat grass is a green grass that grows one to four feet tall. Oat grass has hollow stems and long dark green leaves measuring up to one centimeter wide. The leaves have a rough texture due to the small hairs on them. [19]
Barley Grass
This plant grows two to four feet tall. It is a green to yellow grass with a hairy stem. The head of the plant produces a cluster of flowers or reproductive shoots known as spikelets. [25]
Fescue
Fescue grows two to four feet tall. Fescue produces thick, wide, dark green leaves with prominent veins. [19]
Bluegrass
Bluegrass grows one to three feet tall. Bluegrass produces dark green leaves that are narrower than tall fescue and orchard grass. This plant’s leaves have fine-bladed tips that are shaped like a boat’s bow. [19]
Warm-Season Grasses
Bermudagrass:
This warm-season grass grows four to 16 inches tall. Bermuda Grass produces short flat leaves. The spikelets develop in four or five slender spikes at the tips of the plant’s stems. [19][20]
Teff
Teff grass grows three to four feet tall. Teff produces numerous lateral offshoots originating from the base of the stem. The plant develops a fine stem and grows in tufts. It has a branched flower cluster with spikelets on it. [26]
Bahia
This plant grows 8 to 30 inches tall. Bahia produces a “Y-shaped” seedhead. It is light in colour and has a coarse texture. [27]
Switchgrass
Switchgrass grows three to seven feet tall. Switchgrass produces hairy leaves and develops a dense tuft of hairs where the stem and leaves join. [19]
Sorghum
Sorghum grass typically grows two to eight feet tall but can reach fifteen feet in height. The stalks and leaves of the plant are coated with white wax. Sorghum plants produce clusters of flowers and leaves that are approximately two inches wide and more than two feet long. [20]
Mixed Hays
Mixed grass hays contain several different grass species. Mixed hays that include both grass and legume hays are also popular. [6]
Common blends in North America are alfalfa/timothy and alfalfa/orchard hays.
How to Visually Estimate Hay Quality
Although a laboratory analysis is the only reliable way to measure the nutritional value of your hay, some visual indicators can be used to estimate the hays relative quality.
A recent study suggests people can partially identify hays that have high or low digestible energy content by visual inspection and feel. [34]
Hay with the highest digestible energy content tends to be:
- Dark green
- Thin
- Soft
- Flexible
Hay with the lowest digestible energy content tends to be:
- Yellow
- Dry
- Rigid
- Prickly
- Straw
When fibre content is low and energy and protein content is high, hay tends to be soft, thin, and flexible. Conversely, mature hay with higher fibre content tends to be rigid.
Yellow hay may have experienced significant sun exposure or poor storage conditions, which can also lower its nutritional value.
When evaluating pasture grass, leafy and green pastures will be higher in digestible energy than pastures with abundant seed heads or pastures that have browned off.
Very leafy and green pastures are higher in energy than pastures with seed heads present, which are higher in energy value than completely browned-off pastures.
Nutrient Composition of Grass and Legume Hays
Grass hays have a different nutritional composition than legume hays. The nutrient content of each type of hay also varies according to the stage of maturity, growing conditions and other factors.
Legume hays typically have higher crude protein, calcium, and magnesium levels than grass hay. This type of hay also offers a higher concentration of digestible energy (calories). [28]
Nutrient-dense legume hays benefit horses with increased energy and protein needs, but horse owners will need to supplement additional minerals to balance the high calcium content of legume forages. [11]
Table 1: Summary of historical averages and ranges of grass and legume hay samples submitted to the Equi-Analytical lab between 2004 to 2022. [35]
| Grass | Legume | |
|---|---|---|
| Digestible Energy | 0.9 mcal/lb (0.8 – 1 mcal/lb) |
1.1 mcal/lb (1 – 1.2 mcal/lb) |
| Crude Protein | 11% (7 – 14.8%) |
21% (18.8 – 24%) |
| NDF | 61% (54.6 – 68%) |
38% (33.5 – 43.5%) |
| Lignin | 5% (3.3 – 7%) |
7% (6 – 8%) |
| Starch | 1.4% (0.2 – 2.6%) |
1.3% (0.5 – 2.1%) |
| ESC | 7% (4.6 – 9.5%) |
6.8% (5.2 – 8.4%) |
| NSC | 12.5% (7.6 – 17%) |
10.8% (8.8 – 13%) |
Given how much variation there is in the nutritional value of forages, it is best to submit your forage for analysis to understand its nutritional composition and whether it is the right choice for your horse.
Protein Content
In general, as grass and legume plants mature, protein content decreases, and fibre content increases.
At the same stage of maturity, legumes are typically higher in protein and lower in fibre than grasses, resulting in a higher level of digestible energy.
The difference in protein content of legumes and grasses relates to plant physiology and how the plant stores nutrients.
A major difference between legumes and grasses is their ability to convert nitrogen into protein. Legumes have a symbiotic relationship with nitrogen-fixing microbes found surrounding the roots of the plant. This allows legumes to produce more protein than grasses. [33]
Fiber Content
Fibre is a type of structural carbohydrate that is reported on a forage analysis as acid detergent fibre (ADF) and neutral detergent fibre (NDF).
NDF consists of cellulose and hemicellulose, which are fermented in the hindgut to produce energy for the horse. The NDF fraction also contains lignin which is not fermentable by microbes and does not provide any energy to the horse.
Although lignin content tends to be higher in legumes, it is localized to the plant’s water/nutrient-transporting tissue (xylem) while other parts of the plant remain highly digestible. Conversely, as grasses mature, lignin content increases throughout the plant and has a greater impact on overall digestibility and palatability. [33]
Starch and Sugar Content
A major concern for horse owners is the sugar and starch content of their horse’s forage. Collectively, sugar and starch are non-structural carbohydrates (NSC) found in plants.
High intake of NSC has been linked to several conditions, including gastric ulcers, hindgut dysfunction, equine metabolic syndrome, and laminitis. [8][9][14]
Sugar exists in plants as simple sugars or as complex storage forms consisting of many sugar molecules linked together. Examples of complex sugars include starch, and a type of carbohydrate made up of fructose molecules known as fructans.
Warm-season grasses store excess sugars as starch, whereas cool-season grasses and legumes store excess sugars as fructans. Fructans are digested in the hindgut, whereas starch is digested in the foregut and is broken down into sugars. [6]
The major factor determining sugar and starch/fructan content in plants is the time of day they are harvested. Forage plants use up starch and fructans overnight, so these levels are lowest in the morning and highest in the evening. This variation is greater in grasses than in legumes. [6]
Evaluating Forage Quality
Inspecting hay based on sight, smell, and feel can help you determine forage quality before you purchase it. Depending on their maturity, softness, colour, and odor, different bales of the same hay species can vary significantly in their nutritional content. [29]
A visual inspection can also help predict palatability and ensure that the hay is free of mold. But for precise nutrition information, getting a hay analysis is crucial.
Color
The exterior color of a bale doesn’t always reflect the quality of the hay inside. Opening bales to inspect the inside can provide a better picture of overall quality.
A green color often indicates that the farmer cured the hay correctly. However, some green-colored hays are inferior to brown hays when it comes to nutritional quality. [30]
While sun-bleached hay retains its nutritional value, excess rain after cutting leaches out nutrients and results in color loss. [23]
Hay will also turn dark green or brown if the water content is too high when baled. [30] Dark green or brown can indicate mold growth, which is more likely in moist hay.
Moldy hay is a health concern due to mycotoxins that can impact gut function and respiratory health.
Storing high-moisture hay is also a safety issue, as it is a leading cause of hay fires. If the heat produced during mold growth is not adequately dissipated, hay bales can become dangerously hot. Hay with moisture content above 25% is at risk of spontaneously combusting. [31][32]
Odor
How the hay smells can also reflect the moisture content of forage at baling. [30]
Freshly cut hay should have a pleasant odor. Hay that smells mildewy, musty, or rotten likely has mold. Always inspect hay for mold and odors before feeding. [30]
Softness and Leafiness
Hays with softer texture are usually more palatable for horses than coarse hay. Horses do not like to eat overly coarse stems. [24]
The leaf-to-stem ratio is one of the most critical factors when evaluating hay quality. This is because leaves contain most of the nutrients in the hay, while stems have more indigestible fiber. [23]
A high proportion of blades or leaves indicates that the farmer harvested the hay at a younger maturity. Mature legume hays have minimal leaves as they fall off during the hay-making process [23]
Maturity
Hay maturity directly impacts nutritional value and your horse’s hay intake. Immature plants have higher nutritional values than mature ones because they contain less indigestible fiber. [23]
Horses consume immature hay faster than mature hay. Increased intake and digestibility allow younger plants to provide more nutrients. [23]
A high leaf-to-stem ratio and low density of seed heads indicate younger maturity. Horses with reduced nutrient requirements may benefit from hay with a lower leaf-to-stem ratio and more seedheads. [6]
Hay Analysis
A hay analysis provides detailed information about the nutritional content of your hay. While visual inspection helps identify high-quality hay, it’s impossible to determine the exact amounts of nutrients in the forage without submitting a sample for analysis. [11]
Forage analysis results will include information about the moisture, crude protein, carbohydrates, fibre, digestible energy, and minerals in your hay.
You can read more about interpreting your forage report in our article on How to Read an Equine Hay Analysis.
Once you have your results, upload your hay analysis to our diet evaluation tool and our nutritionists can help you determine if your horse needs additional feed or supplements to meet thier nutritional requirements.
Summary
- Adequate amounts of appropriate, clean forage should provide the foundation of your horse’s diet.
- Forage sources include pasture and hay, which provide the long-stem fiber necessary to support optimal gut function.
- The nutritional value of hay varies depending on the type, maturity, and baling process.
- Inspect your hay’s color, odor, texture, and leafiness to help identify the species and estimate maturity at harvest.
- A forage analysis is the only way to determine the specific nutrient levels in your hay.
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