Forage is the most natural and least expensive feed for horses. Feeding a forage-based diet supports natural grazing behavior and optimal gut health in horses. As such, forage should form the basis of your horse’s diet, with supplemental feeds added only to address any unmet nutritional requirements. [1]

Equine diets often include some combination of pasture grass and hay as forage sources, with the proportion shifting throughout the year as pasture becomes more or less available.

The amount of hay versus pasture in the diet is also influenced by the health and abundance of the available pasture, as well as the individual needs of the horse.

While pasture has the advantage of being nutritious and economical, hay can be bought, stored, and fed year-round. Additionally, a hay-based diet makes it easier to monitor your horse’s forage intake and choose the most suitable forage for them.

Hay and pasture have different nutritional profiles, which must be factored into your horse’s diet to prevent nutrient imbalances. Because of their nutritional differences, it is also important to transition between these forage sources slowly to prevent digestive upset.

Hay vs. Pasture Comparison

Pasture refers to fresh grasses and plants that horses graze on directly from the ground. The nutritional content of pasture varies depending on geographic region, time of year, weather conditions, plant species, soil status, and management practices.

Hay refers to grass or legumes (i.e. alfalfa) that are harvested, dried, and stored for later use, especially when fresh pasture isn’t available. The nutrient content of hay varies based on factors similar to those influencing pasture grass, as well as the timing of harvest and the duration of storage.

Despite the significant variation between different sources of hay and pasture, there are some general differences between hay versus pasture, including:

  • Moisture: Pasture contains more water than hay; 70 – 80% water in pasture vs 10 – 12% in hay
  • Vitamins: Hay is lower in vitamin A, C, and E than pasture
  • Protein: In early growth stages, pasture is higher in protein than hay
  • Energy: In early growth stages, hay is lower in energy than pasture
  • Fiber: Hay is higher in fiber than early growth stages of pasture
  • Digestibility: Pasture is more digestible than hay
  • Non-structural Carbohydrates: Hay is lower in sugar and starch than pasture
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Water Content

One of the most pronounced differences between pasture and hay is their moisture content. Hay is usually dried to contain less than 20% moisture, whereas pasture typically has around 80% moisture.

Due to its reduced water content, hay can be stored for longer periods without spoiling or becoming moldy. Hay should be stored with a moisture content close to 10% to minimize mold growth.

The reduced moisture intake from hay means horses need to have adequate access to fresh water to compensate. Horses on pasture naturally consume more water in their forage, which supports hydration and proper digestion. Adequate water intake is especially important for reducing colic risk by supporting gut motility, or the transit of feed through the digestive tract. [21]

Vitamin Content

Another notable difference between hay and pasture is their vitamin content, specifically vitamins A, C and E. Fresh pasture is naturally abundant in vitamins A, C and E, but hay experiences a decline in these vitamins during cutting, drying, and storage.

Exposure to sunlight and air contribute to the degradation of these essential nutrients once grass is harvested to make hay. When hay is stored, this degradation continues often leading to significantly lower vitamin levels compared to fresh pasture.

While horses manufacture vitamin C (ascorbic acid) and do not develop full blown vitamin C deficiency, i.e. scurvy, a case can be made for supplementation in some situations.

Horses in training for competition have lower levels than pleasure horses. [28] Supplementation with selenium and vitamin C may improve lung health in horses with lower airway disease. [29] Vitamin C in lung fluid is decreased in lung inflammation and improves with supplementation. [30]

On average, hay has 85% less vitamin E content than fresh grass. [2][19]

Studies also confirm that horses on hay diets typically have reduced vitamin A and E levels compared to those on pasture. [13][14][15] While hay is a valuable forage source, it’s essential to supplement these nutrients to ensure horses receive a balanced diet and prevent nutrient deficiencies.

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Protein Content

If comparing the same stand of forage before cutting and after curing and baling, fresh pasture typically has higher crude protein levels and better protein quality than hay. [12]

After plants are harvested for hay, they continue to undergo proteolysis, which refers to the breakdown of protein into nonprotein nitrogen compounds like urea or ammonia which the horse cannot use to make protein. This ongoing protein breakdown reduces the crude protein content of hay and can change the amino acid profile compared to fresh pasture. [2]

Handling practices can also influence the amount of protein in hay compared to pasture. For example, hay that is rained on before baling can experience further losses of protein content.

Leaf shatter also impacts protein levels, especially in legume forages such as alfalfa. Leaf shatter refers to the breaking off or loss of protein-rich leaves from the stems during the haymaking process.

As a result, horses on hay-based diets might receive less protein and fewer essential amino acids than those grazing on fresh pasture, although this depends on the quality of the hay and maturity of the pasture grass.

Non-Structural Carbohydrates

Non-structural carbohydrates (NSC) are fructans, sugars and starch found within plant cells. After forage is cut to make hay, plants continue to respire until they are dried, using up remaining NSC reserves to support respiration. [2]

As a result, hay typically has lower non-structural carbohydrate content than pasture, with an average NSC levels of 11% in hay compared to 15% in pasture. [2]

For some horses, the high levels of the starch and sugar components of NSC in pasture may not be suitable. For example, horses with equine metabolic syndrome (EMS) should have diets that contain less than 10% starch + simple sugars (ethanol-soluble carbohydrates – ESC). These are the carbohydrates that directly impact insulin levels and can increase the risk of laminitis.

Digestible Energy

Due to the combined decrease in protein and higher fibre content, hay usually has lower digestible energy compared to pasture. The higher proportion of fiber in hay makes it less digestible overall. [2]

Digestibility refers to the ease with which a horse’s digestive system can break down and extract nutrients from the hay. A less digestible feed means that a larger portion of the nutrients pass through the digestive system without being broken down and absorbed.

Horses relying primarily on hay as opposed to pasture need to consume more forage dry matter to obtain the same amount of calories and fulfill their energy requirements. Dry matter is what remains after the water content is discounted from pasture or hay.

Nutritional Comparison

The table below compares the nutritional compositions of various hays and pastures. [20]

Forage Type Energy
(Mcal per kg)
Protein
(%)
Fiber (NDF)
(%)
Immature Cool Season
Grass Hay
2.36 18 49.6
Mid-mature Cool Season
Grass Hay
2.18 13.3 57.7
Mature Cool Season
Grass Hay
2.04 10.8 69.1
Warm Season
Grass Hay
1.87 12 75
Mid-mature
Legume Hay
2.43 20.8 42.9
Cool Season
Grass Pasture
2.39 26.5 45.8
Legume
Pasture
2.71 26.5 33.1

Note that several factors impact the protein and digestible energy content of pasture, including:

  • Stage of growth
  • Type of plant
  • Weather conditions
  • Field management

In general, digestible energy and protein content peak during rapid growth and are at their lowest after the plant has matured and dropped its seed.

Nutrition Profile of Hay

Hay is forage that has been cut, dried to less than 20% moisture, and then baled. [1] Although hay is a very common component of equine diets, your horse may not require hay if they get ample access to appropriate pasture.

However, in many regions, pasture grass doesn’t grow adequately year-round to meet a horse’s nutritional needs. This can result in nutritional deficiencies that require supplementing with alternative forage sources.

A clear advantage of hay is its year-round availability, ensuring a consistent forage source regardless of weather conditions. Additional benefits of hay include:

Greater Control

When providing hay to your horse, you have more control over the type of forage provided and can select hay that matches their individual needs. You can choose to feed more or less nutritious hay depending on your horse’s activity level and body condition.

In contrast, the nutritional value of pasture is largely determined by the current growing conditions and the maturity of the plants. Altering the nutritive value of pasture grass may be possible, but takes much longer and requires more resources.

Greater Precision

Feeding hay not only offers greater flexibility in selecting forage for horses but also enables a more precise assessment of the nutritional composition of their diet. When you feed hay, it is easier to monitor how much forage your horse is consuming per day.

You can also submit a hay sample for analysis to obtain detailed insights into its nutrition profile, including energy, protein, fiber and mineral levels. Pasture analysis is also possible, but is less accurate for certain nutrient values and requires careful handling.

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Weight Management

Feeding hay is especially advantageous for overweight horses, as it is typically less energy-dense than pasture. Selecting mature, low energy grass hay allows overweight horses to eat more roughage without contributing to weight gain. However, horses with metabolic syndrome will overeat, making them prone to weight gain even on lower-calorie forages.

Providing less energy dense hay enables continuous feeding and better mimics natural grazing patterns, even in horses that need to lose weight. Horses with metabolic syndrome typically need to have their hay restricted to 1.5% of body weight or 2.0% of ideal weight, whichever is larger.

Hay can be provided in a slow feeder or small hole hay nets to prolong access to hay when forage restriction is required.

Practices such as soaking hay or mixing hay with straw are also good options for reducing calorie intake and supporting metabolic health. Straw still provides some calories but insufficient protein and is often lower in minerals compared to hay.

Weight Gain

Conversely, hay with higher nutritional value can be selected for horses that need to gain weight. Examples of more nutrient dense hay include alfalfa and less mature grass hay.

Furthermore, oils can be mixed into hay to increase calorie supply. This makes hay an especially suitable choice for horses that struggle to maintain optimal body condition on pasture alone.

Hay Selection

So long as you can source an appropriate quality hay for your horse, most can thrive on hay, salt and a vitamin and mineral supplement alone, without the need for commercial grains or concentrates. [1][2]

When choosing hay for your horse, always consider the following important factors:

  • Cleanliness: Hay should be free of weeds, dust, mold, and trash.
  • Aroma: Hay should smell fresh.
  • Maturity at harvest: Plant maturity at the time of harvest directly impacts energy and protein content.
  • Nutritive suitability: Choose a hay that meets your horse’s needs while maximizing forage consumption.
  • Storage conditions: Ensure the hay has been stored in a dry, well-ventilated area, away from direct sunlight and moisture.
  • Texture and palatability: Select hay based on your horse’s individual preferences. Senior horses may need softer hay depending on their dental health.
  • Availability: Choose hay with sufficient availability for your horse to avoid switching forage sources multiple times in a year.

Although feeding hay makes it easier to match your horse’s needs, it is generally more expensive than feeding pasture.

Feeding hay often results in more waste, as horses tend to scatter and tread on their hay rations. Providing forage in a hay net or slow feeder can reduce wastage.

How Much Hay to Feed

When hay is offered free choice (not rationed), horses not in work spend approximately 70% of their time eating hay and consume roughly 2 – 2.5% of their body weight in hay on a dry matter basis per day. [2][3]

For a typical 500 kg (1100 lb) adult horse given free-choice hay, they are expected to consume around 10 kg (22 lb) of hay dry matter daily.

Physiological factors, such as whether a horse is pregnant, growing, lactating, or heavily exercising increase the amount of hay and other feed a horse is likely to consume. These life stages also have different requirements for protein, minerals and vitamins that probably cannot be met simply by increasing hay.

Hay consumption also increases with less fibrous forage, which means that horses tend to eat more when provided with higher calorie, more digestible hay. [4]

Horses may also have a taste preference for different species of forages, impacting how much hay they consume. One study indicated that horses favored timothy hay over orchard grass and brome hay, but were even less interested in fescue and bermudagrass hay. [4]

While studies provide insights into hay consumption and horse preferences, much remains unknown. More research is needed to identify other factors influencing hay intake. [2]

Available Forms of Hay

Hay is typically sold in small square bales, large round or square bales, forage cubes or pellets or as chopped hay. The format you choose depends on your management situation and your horse’s individual needs.

Small Square Bales

Small square bales are the most common form of hay fed to horses. These bales are typically portioned out in flakes and fed daily on the ground or in hay nets or hay feeders. While the weight of small square bales can vary significantly, they typically weigh approximately 50 lbs (23 kg) each.

Since small square bales are portioned and fed daily, they often result in less wastage compared to large bales left free-choice in the field. [1] However, on a per-weight basis, square bales tend to be more expensive than large ones.

Large Round Bales

Large round or square bales are another common hay format, which are often placed in the field for free choice consumption to save time during feeding. Large bales also vary substantially in weight, typically weighing between 500 – 2000 lb (227 kg – 910 kg) each. [1]

While there are cost and convenience benefits to large round bales, leaving bales uncovered outdoors can result in wasting 30 – 38% of the hay. [1] Additionally, these bales can suffer nutritive losses due to exposure to the elements if they are not properly sheltered.

To minimize wastage and nutrient loss, many horse owners use hay nets, rings, or huts to cover and protect large bales during feeding. Inspect netting frequently as horses have been known to eat the netting and develop impactions. [31]

Hay Cubes and Pellets

Hay cubes and pellets are a common form of supplementary forage, generally sold in 50 lbs (23 kg) bags. Different shapes, sizes, plant species and particle sizes are available.

The hay found in cubes is coarsely ground, while hay used in pellets is more finely ground. [1] Regardless of the hay particle size, nutrient digestibility remains consistent across long-stem, cubed, or pelleted hay. [1][2]

However, horses consume cubed and pelleted hay faster than long-stem hay, and these forms also transit the digestive system more rapidly. [1] Horses also tend to eat more of the cubed or pelleted hay compared to long-stem hay. [2][5][6]

Some of the advantages of cubes and pellets include: [1]

  • Reduced wastage compared to long-stem hays
  • Less chewing required, making these a good option for horses with dental issues
  • Low calorie alternative to grains as a supplement carrier for overweight or metabolic horses
  • Easier to transport for competition horses travelling on the road
  • Reduced dust, which makes them a good option for horses with respiratory issues

Since cubed and pelleted forages are consumed and digested more quickly, relying solely on these feeds can result in long periods with an empty stomach between meals. This may contribute to an increased incidence of gastric ulcers and stereotypies such as wood chewing. Smaller, more frequent meals can be fed to avoid this issue. [1]

Chopped Hay

Chopped hay can be purchased at feed stores or made by chopping long-stem hay with a leaf mulcher or hay chopper. Chopped hay may be beneficial for horses with dental issues that make it difficult for them to chew long-stem hay.

Chopping your own hay may also be an economical alternative to feeding soaked cubed or pelleted forages.

Hay Quality

Hay is an important source of nutrition for horses when fresh pasture isn’t available. Hay may also be necessary when the available pasture’s nutritive density is too high for certain horses, such as those at risk of laminitis and when pasture quality drops off late in the growing season.

It is important to match the quality of hay you offer your horse with their individual nutrition requirements. Horses with higher energy requirements need high-quality hay while those with lower energy demands, such as retired horses, can thrive on more moderate-quality forage.

Hay quality encompasses several factors. While it is related to the hay’s nutritional content, it also considers how palatable or tasty the hay is for horses, digestibility, texture, fiber concentration and whether the hay contains any unwanted materials, such as foreign debris. [1]

An average-quality cool season grass hay typically provides around 2 Mcal per kg of dry matter and has a crude protein content between 8 – 10%. These energy and protein concentrations should be sufficient to meet the needs of most mature horses in light work.

Horses in heavy work, such as endurance horses or racehorses, likely need higher-quality forage, such as grass hay harvested at an early growth stage or alfalfa hay added to the diet. Forage that contains 10 – 15% crude protein and over 2 mcal per kg of dry matter would be suitable.

Not All Horses Need High-Quality Hay

Most horse owners want to provide their horses with a high-quality feeding program, but when it comes to forage, higher quality is not always better. Not all horses need the ample amounts of energy and protein that are supplied by high-quality hay.

Instead, you can best support your horse’s health by selecting hay with a nutrition profile that matches their individual needs.

However, it is still important to maintain basic quality standards for your horse’s hay. Ensure the hay is palatable for consumption and free from contaminants such as weeds, mold, dust, insects, or debris.

Quality Indicators

Appearance is often not a good indicator of hay’s quality or nutritive value. While many believe that color, smell, and a ‘soft feel’ indicate hay quality, these characteristics don’t necessarily reflect its nutritional content.

Submitting a hay sample for laboratory analysis is the best way to determine its nutritive value. [2]

The following are some of the factors that influence hay quality.

Nutritive Value:

Hays with higher nutritional value are considered higher quality. The nutritive value of hay depends on many factors, including the type of grass, soil and environmental conditions, plot management, and plant maturity when the hay was cut.

Maturity at harvest is one of the biggest determining factors, with less mature plants typically providing higher nutrient density. [1][2]

More nutritious hays have a greater leaf-to-stem ratio. Since the bulk of a hay’s nutritive value resides in the plant’s leaves, a higher proportion of leaves results in increased energy, protein, and certain vitamin and mineral levels. [1][2]

Digestibility:

The digestibility of a hay is influenced by a number of factors including the plant species, maturity at harvest, leaf to stem ratio, the speed at which the hay was dried, and storage conditions. [1][2][4]

In general, hays with a greater leaf-to-stem ratio have lower neutral detergent fiber (NDF) content. This makes them more digestible, so they are considered higher quality.

Highly digestible hays are beneficial for horses with greater nutrient demands. A moderately digestible hay is often acceptable for mature horses at maintenance or in light exercise.

Conversely, more mature plants are less digestible. These hays may be beneficial for easy keepers or horses that need to lose weight. [2]

However, high fiber hay can often result in free fecal water syndrome in senior horses, secondary to both inefficient chewing and a poor number and diversity in their microbiome.

The following table shows the average dry matter digestibility of different types of hay. [2]

Hay Type Dry Matter
Digestibility
Alfalfa 53 – 63%
Brome 53 – 63%
Bluegrass 45%
Tall Fescue 48%
Bermuda 46%

Palatability:

Hay quality is also determined by its palatability and how readily horses consume it. Factors such as freshness, mold presence, plant species, and maturity at harvest can also influence palatability.

Horses have been shown to consume more forage when highly nutritious hay is provided. [1] However, horses requiring lower quality forage can often adapt to less nutritious hay. [8]

Cleanliness:

High-quality hay should also be clean and free from contaminants, such as debris, weeds and insects. It should also show no signs of mold, as mold can pose serious health risks to horses, including respiratory issues and digestive disturbances.

Types of Hay

While there are many varieties of hay produced in North America, most feed stores and hay dealers in your region will only carry a few types. The best type of hay for your horse depends on their nutritional requirements, as well as considerations of cost and availability.

Hays are primarily classified into grasses and legumes, with grass hays further divided into warm and cool season grasses. These forages differ in nutrient content, cost, and regional availability.

Grass hay is differentiated by its growth temperature preferences:

  • Cool season grasses predominantly grow in the central and northern parts of the US and Canada, thriving in temperatures between 65 – 75° Fahrenheit (18.3 – 23.9°Celsius).
  • Warm season grasses flourish in the southern US, where the climate is hotter with temperatures around 85 – 95° Farenheit (29.4 – 35° Celsius)

These types of grasses also differ in their nutritional value and palatability. While cool season and warm season grasses grow best in different climates, they are commonly shipped to suppliers across North America, making both types available to many horse owners.

Cool Season Grasses:

Cool season grasses grow most rapidly in the Spring and Fall months in cooler climates. [7] Common cool season hay varieties for horses include:

  • Timothy grass: Primarily used for hay, although it may also be grazed. It is often grown with alfalfa to produce “mixed hay”. Alfalfa has the ability to fix nitrogen in the soil where it’s grown, which can enhance the protein content of the harvested hay. [9]
  • Orchardgrass: Often grazed for pasture, but is also a common hay for horses. Orchardgrass can be cultivated on its own or seeded with alfalfa to yield a mixed hay of orchardgrass and alfalfa. [10]
  • Bromegrass: One of the most commonly grown and grazed grasses in North America. Bromegrass is popular because of its resistance to drought, but lacks resilience in the face of close cutting. [11]

Warm Season Grasses:

Warm season grasses grow in warm climates and flourish during the hot summer months. [7] Compared to cool season grasses, these hays typically contain higher fiber (NDF) content and lower non-structural carbohydrate content. [2][8]

Common warm season hay varieties include:

  • Bermudagrass: One of the most important grasses for haymaking in the United States. This type of hay is commonly called “coastal” hay or “Tifton,” a variety favored for its superior nutritional content and yield. [18]
  • Teff grass: Often cultivated during the warmer seasons in cooler climates. Teff hay, with its lower energy and digestibility, is suitable for horses that don’t require a high-nutrient forage. [8]

Legume Hay:

Legume hay is derived from plants in the legume family, which includes beans, lentils, and peas. Alfalfa hay is the most popular legume fed to horses. However, other legumes like peanut and clover are also cultivated and harvested as hay in certain regions of North America.

Compared to grass hay, legume hay is typically higher in: [1][20]

  • Protein
  • Calcium, phosphorus and sodium
  • Soluble carbohydrates
  • Vitamins A and E

The increased nutrient density of legumes makes them a preferred forage choice for mares in late pregnancy or early lactation, growing horses, and heavily exercising horses.

Horses usually favor legumes over grass hays, often consuming larger quantities of legume hay compared to grass hay. [1][2] Legumes typically have broader leaves and finer stems than grass hays, making them more palatable to horses.

However, the leaves of legumes are less securely attached to their stems, making them more susceptible to leaf shatter. This can lead to a greater loss of nutritive value during harvesting, storage, and feeding. [1]

Legume hay is not usually fed to horses as the sole forage source. Typically, legumes such as alfalfa are mixed with grass hay to balance out their nutritional content.

Pasture Grass for Horses

Horses are trickle feeders who evolved to graze and consume small amounts of forage continuously throughout the day. This constant grazing behavior aligns with their digestive system, which is designed to process food in small, steady quantities.

Horses do not require pasture in their diet if they have adequate access to a suitable quality hay. However, turning your horse out to graze pasture is an excellent way for them to express natural foraging behaviors and fulfill their energy and protein requirements.

Pros and Cons of Pasture:

An obvious benefit of grazing pasture is that it can be up to twenty times cheaper than feeding hay. [22] Pasture provides other advantages for both horses and their owners, such as: [1]

  • Companionship: Horses socialize with each other, fulfilling their herd instincts.
  • Free movement: Pastures can provide ample space for horses to roam, exercise, and stretch their legs.
  • Minimizing Confinement: Horses roaming freely have less stress and a lower risk of colic and stereotypic behaviors.
  • Less feed required: Natural grazing can reduce the need for supplemental feeds, providing additional cost savings.
  • Reduced time cleaning: With less time spent inside, there’s reduced need for regular stall cleanings.

Pasture is typically high in energy, protein, vitamins, and minerals, making it an effective way to supply nutrients. However, free choice pasture often exceeds nutritional needs for idle mature horses, which can lead to obesity and increase the risk of insulin-related laminitis in horses with metabolic syndrome. [1][2]

Pasture also requires effective management for it to be productive, and might not work for every horse.

The decision on whether and how long to graze pasture should strike a balance between fulfilling nutritional requirements and optimizing pasture productivity for cost savings.

Nutritive Value of Pasture

Most pastures contain several types of grasses, meaning that the nutritive value varies from plot-to-plot. [1][2][23] The nutrition provided by pasture also depends on plant digestibility and how much pasture grass horses are willing to consume. [2]

While pasture can satisfy the nutritional needs of many horses, those on a pasture-only diet should receive a vitamin and mineral supplement to ensure comprehensive nutrition. [1][2] Essential nutrients like sodium, zinc, and copper are likely undersupplied in pasture-only diets. [24]

Horses with higher nutrition requirements may need additional sources of calories in their diet. Pasture alone may not meet the energy or protein needs of horses in very heavy exercise or mares in late gestation or early lactation. [2][12] Calcium and phosphorus levels might also fall short for horses in moderate to heavy work and pregnant or lactating mares on a pasture-only diet. [24]

Seasonal Variation:

The nutritional profile of pasture fluctuates throughout the year due to seasonal variations. Typically, pastures are most nutritious during spring and fall, with energy density declining from spring to fall. [1][2] This shift corresponds with changes in non-structural carbohydrate content.

NSC content often peaks in late spring and early autumn. Additionally, spring grasses might see elevated sugars during phases of rapid plant growth.

Digestibility:

The digestibility of pasture grass depends on the type and species of plant, as well as its maturity at grazing time. Cool season grasses are usually more digestible than their warm season counterparts, with noticeable variations even within a grass type. [25]

As plants mature, they become more fibrous and less protein rich, resulting in lower digestibility with age. [1] Horses grazing any given pasture face changes in nutritive value, digestibility, and forage abundance throughout the grazing season.

In the late summer and fall, mature growth of pasture grasses results in a higher stem-to-leaf ratio. Because plant stems are higher in fiber, pasture may be less digestible during this period. [26]Pastures grazed later in the growing season may also produce grass that is lower in energy, non-structural carbohydrate, protein, mineral, and fat content. [1]

Pasture Grazing Behavior

The optimal amount of pasture turnout for your horse should consider both the abundance of pasture and your horse’s nutritional requirements. However, the amount of grazing time that can be offered to a horse might not always match their natural grazing habits.

Several factors influence the amount of time a horse spends grazing when turned out on pasture:

  • Ambient temperature
  • Forage availability
  • Pasture quality, digestibility, and palatability
  • Presence of other horses
  • Presence of pests, such as flies
  • Age of the horse

Horses with free access to pasture are expected to spend spend 40-60% of their time grazing under favorable conditions. [1]

Although preferences vary from horse to horse, in general horses prefer mixed grass pastures over grass- or legume-only fields. Plant maturity, species and time of year also impact palatability and how much pasture grass the horse will consume. [26]

If the pasture is abundant and palatable, horses typically consume about 2% of their body weight in pasture dry matter per day. [20] For a standard 500 kg (1100 lb horse), this translates to 10 kilograms (22 pounds) of pasture dry matter.

Grazing Management

Although pasture is an economical way to provide forage, it must be managed properly to keep it safe and productive for your horse. Without adequate management, the nutritional quality of pasture can decline, and there’s an increased risk of horses being exposed to toxic plants. [23]

Stocking Density

One of the most important grazing management decisions is how many horses to allow on a given pasture. It is also important to determine how long they will be allowed to graze so as to not overwhelm the pasture with more grazing than it can sustainably support.

The term stocking rate or stocking density refers to the number of animals kept on a specific pasture area. Effective stocking rates vary based on pasture productivity, but it is recommended to allocate at least 2.5 acres per horse. [2] A very carefully managed pasture may support one to two horses per acre during the growing season. [1]

Higher stocking rates are feasible only on highly productive pastures. Factors influencing grass growth and pasture yield include: [1][23]

  • Soil temperature, type, and fertility
  • Moisture levels
  • Light intensity
  • Pasture management strategies

An improper stocking rate and poor grazing management can lead to issues such as overgrazing or undergrazing of plant species in a pasture.

Overgrazing

Overgrazing is a common pasture management issue that occurs when grazing intensity exceeds the pasture’s recovery capacity. This refers to the pasture’s ability to regenerate and grow back after being grazed.

Overgrazing can deplete the soil’s nutrients and lead to soil erosion. As a result, the pasture becomes less productive, with sparse grass cover and an increase in undesirable weeds.

Signs of overgrazing in a pasture include: [23]

  • Visible piles of feces with horses grazing nearby
  • Bare soil patches
  • Sparse grass
  • Prevalence of weeds

Overgrazing hampers plant regrowth, reducing pasture yield and quality. It’s advised not to graze pasture grass below 2 inches, or 4-6 inches during fall. If a pasture is overgrazed, horses should be relocated to allow the pasture to recover, rather than just supplementing with hay. [23]

Undergrazing

Undergrazing results from insufficient grazing or cutting, leading to the dominance of less preferred plant species. This is because some cutting or grazing actually favors growth of pasture grasses. [23]

If your horses aren’t regularly grazing a pasture, it’s important to maintain the grass by cutting it to 4 inches (10 cm) or higher to maintain grasses in the vegetative stage and prevent weeds from spreading their seeds. [23]

Management Strategies

To keep pastures healthy and productive for your horses, consider the following strategies: [23]

  • Plant appropriate grasses
  • Using different grazing management systems such as rotational grazing, strip grazing, or sacrifice areas
  • Make hay available for at least four hours before horses are turned out onto pasture
  • Limit grazing to a few hours per day, where necessary
  • Co-graze with other animals such as sheep or cows
  • Conduct regular mowing and harrowing

Forage Transitions

Forage transition refers to the process of changing a horse’s primary source of roughage, whether from one type of hay to another, from hay to pasture, or vice versa. Properly managed forage transitions are crucial for maintaining optimal digestive health and overall well-being.

The equine digestive system is populated by a diverse community of microbes that help break down fibrous plant material. A sudden change in forage can disrupt this microbial balance, potentially leading to digestive upsets, such as colic.

The transition from hay to pasture in the spring is a common cause of concern for many horse owners. However, less attention is given to the transition from pasture to hay in the fall or winter.

Transitioning from Pasture to Hay

Transitioning a horse from pasture to a diet of hay and concentrates has been shown to temporarily increase fecal pH, indicating lower levels of acidity in the hindgut. [16]

Switching from pasture to hay increases the presence of Streptococcus and Lactobacillus bacteria in the feces, suggesting changes in the hindgut microbial population. [16][17]

As with any major change in your horse’s diet, the transition from pasture to hay in the fall should be made carefully and slowly. Abrupt changes can lead to digestive issues and increase the risk of impaction colic in horses and donkeys due to the lower moisture content of hay. [21][27]

Horses transitioning from pasture to hay should have constant access to fresh water to support adequate hydration and gut function. Also, add plain loose salt to your horse’s diet to ensure their sodium requirement is met. Salt stimulates thirst and encourage proper hydration.

Preventing Weight Loss

Weight maintenance is important to consider during this transition. Weight loss can occur for a number of reasons when switching your horse from pasture to a hay-based diet, including:

  • Lower energy density of hay compared to pasture grass
  • Increased energy demands to maintain body temperature during cooler weather in the fall and winter
  • Loss of water weight with the transition to a lower moisture forage
  • Dental issues related to difficulty chewing hay

To prevent sudden weight loss when transitioning from pasture in the fall, ensure you choose hay that is palatable and matches your horse’s nutritional requirements.

If you will be feeding hay as your horse’s primary forage, submit a hay sample to analyze its nutritional content. If your hay does not meet your horse’s energy and protein needs, consider supplementing with a richer feed or forage to fulfill calorie requirements.

Gradual Transition

One of the best ways to ensure a smooth transition from pasture to hay is to make the change gradually. Gradual transitions give your horse’s gut microbiome time to adapt, which can improve nutrient absorption and prevent digestive upset.

Pasture access can be incrementally restricted over the course of a few weeks while increasing hay provided to your horse. Pasture restriction will not only support your horse’s transition, but may also prevent overgrazing of fall grasses.

You can also feed hay before turnout to help your horse adapt to their new forage and prevent overconsumption of pasture once they are turned out.

Also consider supplementing with a probiotic and prebiotic supplement during forage transitions to help maintain a healthy microbiome. Mad Barn’s Optimum Digestive Health is formulated with probiotics, prebiotics, yeast and digestive enzymes to support your horse’s hindgut and reduce the risk of gut issues.

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Summary

Forage is the cornerstone of the equine diet, and most feeding plans contain some combination of hay and pasture. When balancing your horse’s diet, there are some key difference to keep in mind between hay versus pasture:

  • Pasture has higher water content than hay.
  • Hay is deficient in vitamins A and E, requiring supplementation in horses on hay-only diets.
  • Hay generally has lower energy and ESC (sugar) and starch content than pasture, making it beneficial for overweight and metabolic horses.
  • Hay contains more fiber than pasture and is less digestible.

Both hay and pasture offer distinct advantages and disadvantages. You can select the best forage source for your horse by considering their activity level, physiological status, and body condition, as well as your budget and forage availability in your region.

Adjusting the proportion of hay and pasture in your horse’s diet can also help to overcome seasonal variations in forage quality and quantity. Whenever switching between forage source, remember that the transition must be made gradually to avoid digestive issues or other health problems.

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References

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  4. Fonnesbeck, P.V. et al. Digestibility of the Proximate Nutrients of Forage by Horses. JAS. 1967. View Summary
  5. Haenlein, G.F.W. et al. Comparative Response of Horses and Sheep to Different Physical Forms of Alfalfa Hay. JAS. 1966.
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  14. Pitel, M.O., et. al. Influence of specific management practices on blood selenium, vitamin E, and beta-carotene concentrations in horses and risk of nutritional deficiency. Journal of Veterinary Internal Medicine. 2020.View Summary
  15. Cappai, M.G., et. al. Variation of Hematochemical Profile and Vitamin E Status in Feral Giara Horses From Free Grazing in the Wild to Hay Feeding During Captivity. JEVS. 2020. View Summary
  16. van den Berg, M., et. al. Fecal pH and Microbial Populations in Thoroughbred Horses During Transition from Pasture to Concentrate Feeding. JEVS. 2013.
  17. Garber, A., et. al. Abrupt dietary changes between grass and hay alter faecal microbiota of ponies. Plos One. 2020. View Summary
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