Short grass or long grass for horses? Which is best?

Apr 09, 2021

That is the question! Traditionally horse owners have been told to keep horses (and ponies and donkeys) on short grass if they want to manage their weight (and prevent laminitis etc.).

But you need to know the pros and cons of grazing horses on short grass plants versus longer grass plants.

What are the problems with short grass for horses?

It is usually stressed grass, constantly trying to recover/grow. Therefore it will store/hang on to a lot of Non-Structural Carbohydrates (NSCs) (sugars/starches) in preparation for when growing conditions improve.
Each mouthful is relatively high in NSCs because sugar/starch is stored at the base of the plant. So each mouthful has a high NSC/fibre ratio.
Generally the further up the stalk the horse eats, each cell of the plant has a higher fibre/sugar ratio.
Eating longer grass means the horse has to chew more, slowing the intake while increasing the essential flow of saliva. The saliva helps to buffer the stomach acid.
A healthy horse eats until they have a specific volume of fibre in their stomach before stopping. So eating grass with a high-sugar and low fibre ratio means a horse consumes a lot of high-sugar grass before enough fibre is ingested to trigger that 'full enough' feeling and finish their grazing bout.
We should focus on increasing our pastures' fibre content, which will reduce the NSC intake.
Horses on short grass are not getting their fibre requirements met; see this article for more information about their fibre requirements www.equiculture.net/blog/what-is-essential-feed-for-a-horse
Horses have the perfect equipment to eat short grass (two pairs of incisors that meet in the mouth like sharp scissors). Horses can eat their fill (and get/remain fat) on grass plants that are 3cm - 4cm, ponies can do the same on 1cm - 2cm (1 inch = 2.54cm).

Horses have the perfect equipment to eat short grass (two pairs of incisors that meet in the mouth like sharp scissors).

'Lawn' types grasses have their growth points very low down the plant and can cope with being kept constantly short. These grasses have been selected and bred/developed further for lawns, golf courses, etc. Overgrazing results in only the 'lawn' type grasses surviving - so the result is a monoculture of just one or two types of grass plants.
Short grass plants have short root systems that cannot reach far down in the soil for nutrients.
A short root system results in much less organic matter in the soil, causing soil compaction and poor drainage (and less carbon sequestration - significant for climate change mitigation).
Short, sparsely grassed areas in a paddock quickly turn to mud in wet weather and dry out very quickly (become dusty) in dry weather. Both lead to soil loss.
Horses are more likely to pick up sand while grazing short grass (if the soil is sandy).
If horses graze short grass for a long time, they can abnormally wear the front teeth (incisors), especially if the soil is sandy/gritty.
Short grass plants are not as able to outcompete certain weeds.

Overgrazing (to produce short grass) results in only the 'lawn' type grasses surviving - so the result is a monoculture of just one or two types of grass plant.

How short is short grass for horses?

Short grass is generally shorter than 5cm (2.5 inches). Still, it would be best to look at the average height across your pasture as you will have several species (unless you have created a monoculture) and possibly 'toilet areas' ('roughs'). In reality, on many horse properties, the plants are kept down to 2cm (1inch) or even 1cm (1/2inch) (especially if the owners are trying to restrict their horse's grass intake), but remember, horses have just the right equipment to eat grass no matter how short.

Many horse owners think a paddock full of grass that is 5cm long would be regarded as too long/tall. At 5cm, the plant is just about reaching the stage where it has 2 to 3 leaves, and it can now start to make a rapid recovery, using its stored sugars/starches for growth; at less than 5cm, it becomes stressed.

What is good about long grass for horses?

Taller pasture plants provide a habitat for beneficial insects, small mammals/reptiles, and ground-nesting birds.
Taller pasture plants create more biodiversity because a wider variety of plants get to grow, set seeds, and multiply.
Taller pasture plants mean longer/thicker root systems, meaning that more healthy nutrients are brought up from deeper layers in the soil.
With their longer/thicker root systems, taller pasture plants sequester more carbon than short plants and quicker than trees! This function is improved when the plants are repeatedly grazed and then allowed to regrow (as part of a rotational grazing system), effectively 'pumping' carbon into the soil.
Longer/thicker roots equal better soil protection (less or no mud/dust), so plants can be grazed in wetter conditions for longer (to a point).
Taller pasture plants keep the soil warmer in cold weather.
Taller pasture plants shade the soil in hot, dry conditions, keeping it cool and reducing evaporation. This, plus the increase in soil organic matter, helps hold water in the soil for longer - essential in dry conditions.
Taller plants shade out and outcompete many weed species.
Taller pasture plants are healthier, not stressed, and are in what is called 'the growth phase'.
When the roots are longer, the plant 'trades' some sugars for other nutrients such as amino acids (when the grass is short and stressed, it hangs onto these excess sugars).
Taller pasture plants have a higher fibre-to-sugar ratio than short grass; this is good.
The horse has to eat the longer fibres before getting to the higher sugar part of the plant (at the base of the plant).
The horse has to chew more - much healthier- creating saliva to buffer stomach acid.
Horses walk more when grazing longer, more diverse pasture as they seek out different plants.

How long is long grass for horses?

In a rotational grazing system of land management, the grass is regarded as tall enough to resume grazing when it is approximately 15cm (8 inches) tall (or just before it 'goes to seed'). When the grass plants have been grazed down to an average height of 5cm (2.5 inches), the animals should be removed and the grass given the chance to rest and recuperate. This grazing and resting also creates a healthy root system and vastly increases organic material in the soil.

So you can see how this is very different from how pasture is managed on most horse properties.

Where does the outdated information about short grass for horses come from?

Traditionally, much of the information about grazing horses comes from grazing farm animals such as cattle. Cows cannot eat very short grass to the same extent as horses because they only have one set of incisors and use their tongue (by wrapping it around the plant) to graze. So the plant needs to be taller for them.

If you forced a cow to graze short grass plants, it might eventually starve. It is often assumed that horses are like cows - but they are not; they have very different teeth and a significantly different digestive system!

How can you learn more about horses, land management and the environment?

Start by signing up for the free mini-course about Horses, pasture and grazing www.equiculture.net/equiculture-free-mini-course.

So, it has always been assumed that if you put a horse on short grass, it will lose weight. However, this does not necessarily happen.

Most horses will eventually lose or maintain weight if the grass is extremely short to almost nonexistent. Still, the grasses are highly stressed at this stage, and land degradation is taking place, resulting in soil loss/erosion/compaction, less biodiversity, mud, dust, etc.

We need to give horses more fibre and less sugar (NSC). A horse's digestive system relies on a specific volume of feed passing through it, so it is essential to make this fibre rather than sugar; in human terms, that would be more salad and less chocolate.

Why you must not treat soil like dirt on a horse property!

You will lose topsoil (which has taken aeons to make).
You will grow less viable feed and have to buy in more feed.
You will have mud for large parts of the year (and compacted, dusty soil for the rest).
You will have more weeds etc.
It is not sustainable to do so.

How can you make the transition to longer grass for horses?

If your horse has been grazing a restricted diet of short grass and would like to make the change, you must slowly and very carefully manage the transition to grazing longer grass. You cannot suddenly switch as that horse initially will gorge when given 'free rein'.

Make sure you also read this follow-up article about how to make the transition if that is what you decide to do: www.equiculture.net/blog/switching-a-horse-to-grazing-longer-grass-plants

In most cases, this is best done over winter when there are generally fewer NSCs in the plants.

Of course, you cannot let your horse overeat on long grass until they have learned to self-regulate (some horses will - some won't). Also, some grass types are much higher in sugar than others. But once you know how it is usually possible to manage your horse on longer grass and reap the other benefits listed in this article.

And again, make sure you read this article next: www.equiculture.net/blog/switching-a-horse-to-grazing-longer-grass-plants

Read the stories on this page Equiculture endorsements from people who have changed from short grass to long grass, and some with very challenging horses and circumstances.