Grass: the biggest sugar bomb for your horse The advice and information platform for all horse and dog enthusiasts.

Grass and hay contain varying amounts of carbohydrates such as sugars, starch, and fructan. The amount of sugars in the grass depends on the time of day and the season. The type of grass in the pasture also has an influence. Excessive intake of sugars, starch, and fructan is associated with digestive issues and metabolic diseases such as laminitis, insulin resistance, and EMS in horses. Horses with summer eczema or those sensitive to mites also benefit from a low-sugar diet.

Tip: Pay attention to the fructan index

Most horse owners are familiar with the fructan index, a handy tool available online to check if it’s safe for your horse to graze. Especially on a sunny morning after a cold night, the fructan content in grass can be very high, posing a risk of laminitis. However, it's not just the fructan content that matters. Measuring the insulin levels in a horse’s blood can give an indication of all sugars in the grass. Research in the Northern Hemisphere has shown that the insulin levels in grazing horses are highest in April, followed by May. High insulin levels in the blood can lead to insulin resistance in horses. Therefore, you should avoid letting your horse graze for too long or too often when there are high levels of sugars in the grass. Also, harvesting hay during these times may not be a good idea.

Cow grass for horses is protein-rich

In the Netherlands, many pastures are still sown with 'cow grass'. This is grass (English ryegrass) that is high in energy and protein. This grass is actually meant for dairy cows, which are akin to top athletes, needing to produce a significant amount of milk daily. Cows require a lot of sugars and proteins for this and have four stomachs to digest all that rich grass. Horses, on the other hand, originally come from the steppes where they chewed on dry, coarse stems all day. Their digestive systems are designed to extract as much energy as possible from low-sugar plants. Horses are therefore not suited for this rich cow grass.

On average, a kilo of sugar per day

You might wonder how much sugar is in that grass. Well, it can be quite a lot. Did you know that a horse can consume up to a kilo of sugar per day under unfavorable conditions? As an owner, you can do your best to feed low-carb balancers, but that will hardly make a difference. If you have an insulin-resistant or laminitis-prone horse, it's wiser to scrutinize your grass and hay.

It's not just temperature and sunlight that affect fructan levels. Did you know that when the soil lacks water and/or nutrients, the fructan content is always higher? It's important to provide the soil with pasture minerals three times a year.

Hay and grass for sensitive horses

Sensitive horses are sometimes better off in a paddock rather than a pasture. Give them low-sugar hay, preferably made from horse grass: poorer grass varieties with long, fibrous stems. When grass is harvested at times when it has high sugar content, the hay will also contain more sugar. That's why horses often receive hay that has been stored longer and is not from the first spring harvest (the so-called 'first cut'). If you fear that your hay is too rich, you can soak it in cold water for an hour. This helps to remove a lot of sugars without losing too many proteins and other nutrients.

Short grass is richer in sugar than long grass

Did you know that short grass contains more sugar than long grass? Grass that continues to grow and blooms is also called bolting grass. Long grass contains less leaf material and more stem material. The more bolting the grass, the more fibers it contains. The grass becomes more woody, making the horse work harder to chew and digest it.

Therefore, be cautious with horses that are prone to laminitis, summer itch, or insulin resistance when it comes to short grass. A sparse pasture with short grass is often seen as ideal for these horses. However, the fresh shoots that are actively growing are real sugar bombs. Long grass through strip grazing is often the best option for these horses.

When is it safe for your horse to graze?

This, of course, depends on the type of grass and whether the soil has enough water and nutrients. Grass that lacks nutrients to grow always has a higher fructan content. Always keep an eye on the fructan index and gradually build up the grazing season. Start with an hour a day for a week, then two hours the following week, preferably using strip grazing. If the nighttime temperature has been around or below freezing, it’s best not to put your horse on the fresh grass the next day.

Safe to graze:

Early in the morning if the nighttime temperature hasn’t dropped below 5 degrees Celsius.
On a cloudy day when the temperature is above 15 degrees Celsius.
During warm sunny weather, at night and in the morning.
During warm cloudy weather, in the afternoon and evening.

Better not to graze when:

After a night where the temperature was around freezing (below 5 degrees Celsius).
On a sunny day when the temperature stays below 15 degrees Celsius.
When the grass is short-cut or heavily grazed.