Horse Pasture: Which Grasses Are Best for Your Horse?

October 7, 2026

Understanding horses’ digestive needs

Horses possess a unique digestive system that thrives on a continuous supply of nutrient-dense, high-fibre forage. This forage is digested through fermentation in the hindgut, providing essential nutrients and energy.

The type of grass your horse eats can have a significant impact on their digestive health, nutritional balance and general wellbeing. Different grasses contain varying levels of fibre, sugars, protein, minerals and naturally occurring compounds, some of which can cause problems for susceptible horses.

Understanding what is growing in your horse's paddock is an important part of managing their diet.

Impact of grass moisture content

The moisture content of grass significantly affects fibre intake. Green grass typically contains more water and less fibre by weight than dry, mature grass. Horses grazing on lush grass day and night without adequate fibre can develop imbalances in their gut microbiome.

A horse's hindgut acts as a fermentation vat, breaking down fibre and producing fatty acids that provide energy. Maintaining a consistent supply of suitable forage supports this natural digestive process.

Ideal grass for horses

Mature, dry grass provides valuable fibre for horses. However, many horses graze on short, green, fertilised or unsuitable grass species that have been selected for livestock such as cattle and sheep. These pastures can encourage rapid weight gain and may supply excessive sugars, protein or other nutrients for some horses.

Horses generally benefit from a forage-based diet that provides plenty of fibre without excessive energy or unsuitable mineral levels.

Even grasses generally considered suitable can vary considerably in their nutritional composition. Growth stage, weather conditions, soil fertility, rainfall, drought, frost and fertilisation all influence what a horse consumes.

Risks of unsuitable grass

Some grass species can contain high levels of sugars, fructans, protein, nitrogen, potassium, oxalates, mycotoxins or other naturally occurring compounds. These can affect susceptible horses in different ways, from influencing mineral absorption to contributing to digestive, metabolic, skin or behavioural problems.

Even a suitable grass species can become problematic under certain conditions, including spring or autumn growth, after frost, following fertilisation, after drought-breaking rain or when pasture becomes overgrazed.

If your horse isn't grazing mature, dry pasture, provide suitable grass hay to maintain adequate fibre intake.

Identify your pasture grass

Knowing which grasses and plants grow in your horse's paddock helps you make better feeding and management decisions. The following guide outlines common pasture grasses, their potential concerns and the species to watch for.

Generally suitable grasses for horses

The following grasses can provide useful forage when they're suited to your climate and managed appropriately. Their nutritional composition will still depend on growing conditions and maturity.

**Rhodes Grass**: Subtropical to tropical & dry climates.

**Creeping Blue Grass:** Temperate climates with moderate rainfall.

**Kangaroo Grass:** Warm, dry climate. Drought tolerant.

**Wallaby Grass:** Temperate climate to subtropical regions.

**Red Grass:** (Bothriochloa macra) Warm, dry climate.

**Weeping Grass (Microleana):** Warm, humid environments.

**Spear Grass:** Warm temperate climates. Drought tolerant.

**Timothy Grass:** Cool temperate climates.

**Yorkshire Fog Grass:** Cool, moist temperate regions.

**Queensland Blue Grass:** Warm, humid, subtropical climate.

**Brown Top:** Cool, moist temperate climates.

**Pangola / Digitaria Grass:** Warm
climates. Drought tolerant.

Problem Species

**Rye grass:** High in potassium and sugars; risk of metabolic disorders & ryegrass staggers. Endophyte fungi living inside the grass can produce mycotoxins

**Clover:** Contains phytoestrogens that disrupt hormone balance, very high in starch & contains phytodynamic pigments which can lead to mud fever and skin issues & can aggravate head flicking.

**Tall Fescue:** Associated with reproductive problems for pregnant mares due to fungal endophyte and laminitis.

**Kikuyu Grass:** High in sugars; risk of metabolic disorders and oxalate.

**Couch Grass:** Difficult to control; prone to overgrazing & oxalates.

**Sweet Vernal Grass:** Contains coumarin, which is toxic if it gets mould.

**Paspalum:** High sugar content and can get ergots on seedheads during humid weather. Also risk of paspalum staggers.

**Phalaris:** Can cause neurological problems such as phalaris staggers.

**Cat's Ear:** Potentially harmful toxins which can lead to stringhalt. Often confused with dandelion!

Oxalate grasses and calcium absorption

Oxalates occur naturally in several pasture grasses. They can bind with calcium in the digestive tract, reducing the amount available for absorption into the bloodstream.

The amount of calcium bound depends on the oxalate concentration in the grass and the quantity consumed. Long-term exposure to high-oxalate pasture can contribute to calcium-related problems, including nutritional secondary hyperparathyroidism, commonly known as big head disease.

Signs associated with prolonged calcium imbalance can include facial swelling, skeletal changes and muscular problems.

Common oxalate-containing grasses

The following grasses can contain significant levels of oxalates:

Setaria: Can contain very high levels of oxalates.
Buffel grass (Cenchrus ciliaris): Oxalate levels can be significant.
Kikuyu (Cenchrus clandestinus): Can contribute substantial oxalates to the diet.
Green Panic (Megathyrsus maximus subsp. pubiglumis): May contain steroidal saponins and moderate levels of oxalates.
Pangola or Digitaria grass: Can contain oxalates.
Guinea Grass (Megathyrsus maximus subsp. maximus): Can contain oxalates.
Para Grass (Urochloa mutica): Can contain oxalates.
Signal Grass (Urochloa decumbens): Can be high in oxalates.
Couch Grass (Bermuda): Can contain oxalates.
Buffalo Grass: Can contribute oxalates to the diet.

**Green Panic:** Megathyrsus maximus subsp. pubiglumis: May also contain steroidal saponins.

**Pangola / Digitaria Grass:** Warm, humid climates. Drought tolerant.

**Guinea Grass:** Megathyrsus maximus subsp. maximus

When horses graze predominantly on oxalate-containing grasses, their overall diet and calcium intake need careful consideration.

Not all calcium supplements are equal. A suitable chelated mineral blend such as Xtracal can help provide nutritional support when managing horses grazing oxalate-containing pasture.

For more information, read our guide to oxalate grass and how to manage it.

Other compounds in pasture that may affect horses

Oxalates aren't the only naturally occurring compounds worth considering when assessing your horse's pasture. Potassium, fungal toxins and plant pigments can also influence the suitability of certain grasses and plants.

Potassium

Potassium is an essential mineral, but some grasses and feeds contain relatively high levels.

Lucerne, clover, kikuyu and ryegrass can contribute significant amounts of potassium to the diet. Some horses are particularly sensitive to high-potassium diets, especially when several high-potassium feeds or pasture types are combined.

When assessing a horse's diet, consider the total potassium supplied by pasture, hay, supplementary feeds and mineral products rather than looking at one grass in isolation.

GrazeEzy is one of the nutritional products available from Greenpet for horses affected by pasture.

Mycotoxins

Mycotoxins are substances produced by certain fungi. They can occur in pasture, hay and other feedstuffs when conditions allow fungal growth.

Potential sources include ryegrass, tall fescue, paspalum, phalaris, couch, clover and kikuyu. However, the presence and concentration of mycotoxins depend on the plant, fungal species, environmental conditions and feed storage.

Some horses may be more sensitive to affected feed than others. Changes in behaviour and general wellbeing can be signs that the overall diet and feed quality deserve closer attention.

Good pasture management, appropriate hay storage and careful observation of your horse can help identify whether feed quality may be contributing to a problem.

ToxDefy is available as nutritional support for horses where dietary toxins are a concern.

For more information, read our guide to mycotoxins and what they are.

Fluorescing pigments and photosensitivity

Some pasture plants contain naturally occurring pigments or other compounds that can contribute to photosensitivity in susceptible horses. Certain compounds become photodynamic, meaning they can react with sunlight and damage exposed skin.

Plants such as clover, lucerne, St John's wort, buttercup and plantain may be associated with photosensitivity.

Affected horses can develop redness, soreness, inflammation or skin damage, particularly on areas exposed to sunlight. These changes can sometimes be mistaken for ordinary skin irritation or mud-related skin problems.

If your horse develops unexplained skin sensitivity, review the pasture and other potential dietary contributors.

Clover and other legumes

Clover and other legumes, including lucerne, contain naturally occurring compounds that can influence horses differently depending on the species, variety and individual animal.

Some horses appear particularly sensitive to clover-rich pasture or diets containing substantial amounts of legumes. Certain plants may also contribute to photosensitivity, while fungal associations can introduce additional concerns.

If you notice unusual reproductive, behavioural or skin changes, review the horse's pasture, hay and overall diet to identify potential contributing factors.

Toxic Trees and Plants to Avoid - Read our blog post on Toxic Plants

It's crucial to make sure your horse's pasture is free of harmful plants, especially when grazing options are limited, as they may resort to eating undesirable plants when they're hungry. Offering a varied diet supports a healthy gut microbiome, and horses often seek out specific plants for their nutrients or medicinal properties.

It's important to keep your horse's pasture free of harmful plants, particularly when grazing options are limited. Hungry horses may consume plants they would otherwise avoid.

A varied forage diet can support a healthy gut microbiome, but not every plant a horse chooses to eat is safe. Knowing which plants grow in your paddocks is essential.

Know what is growing in your horse's paddock

Pasture is much more than simply grass. Different species can provide very different levels of fibre, protein, sugars, minerals and other naturally occurring compounds.

Knowing which grasses and plants grow in your paddocks helps you make better feeding and management decisions, particularly if your horse develops unexplained changes in behaviour, skin sensitivity, soundness or general wellbeing.

When assessing pasture, consider the whole picture:

Grass species: Identify the grasses and weeds growing in the paddock, including those that may contain oxalates or other potentially problematic compounds.
Grass maturity: Mature, dry grass generally provides more fibre by weight than lush, young growth.
Seasonal conditions: Spring growth, autumn growth, frost, fertilisation and drought-breaking rain can all influence pasture composition.
Hay quality: Check the type, maturity, condition and storage of your horse's hay.
Total diet: Consider sugars, protein, minerals, supplements and the overall balance of the diet.
Individual needs: Age, workload, body condition and individual sensitivity all influence which pasture is suitable.

No single list of grasses will suit every horse. Understanding your pasture and providing appropriate forage are important steps towards supporting your horse's digestive health and overall wellbeing.