Think Fibre First!

The Importance of a High Fibre Diet for Horses!

The horse is classified as a non-ruminant herbivore and has evolved over millions of years with a specialised digestive tract adapted to digest and utilize diets containing high levels of plant fibre. As horses have evolved to eat a high fibre diet, their digestive tract is at its healthiest when consuming high fibre diets. Forages that are high in fibre tend to take longer to eat if fed as long or short chops relative to pellets and mixes. This helps to satisfy the horse’s inherent need to chew and so is very important for their behavioural welfare too. As society’s relationship with domesticated animals evolves, it is ever more important to think carefully about how we feed and manage horses to support their health and welfare.

Benefits of a high fibre diet for horses

Fibre for Digestive Health

As fibre takes longer to chew a horse will naturally produce more saliva, which helps to moisten and soften the food to make it easier to swallow. Saliva also contains bicarbonate which is needed to regulate and neutralize the acidity of the horse’s stomach contents.

FACT: More fibrous materials help to increase saliva production as there is a direct relationship between the amount of force used when chewing and the amount of saliva produced. More natural buffering in the digestive tract will occur compared to when softer feed materials are fed. (Vervuert, 2012)

Low fibre diets combined with higher starch rations are linked to a number of digestive issues in horses, including equine gastric ulcer syndrome (EGUS). When it comes to ulcers, not all fibre is the same; research has shown that alfalfa is a superior buffer to acidity in the digestive tract compared to grass forages due to the abundance of calcium it contains.

Fibre is also important for encouraging gut motility. Just like humans, the horse needs plenty of fibre to keep everything moving through the digestive tract and to promote regular bowel movements. Too little fibre in the horse’s ration can also result in build-ups of gas, which can lead to colic symptoms.

Fibre for Energy

Fibre is fermented in the horse’s hind gut by microbes which produce volatile fatty acids (VFAs). These can be utilized directly or stored as fat in adipose tissue at times of surplus. It is also possible for VFAs to ultimately be converted to glucose and although this isn’t the most efficient form of energy metabolism, it does mean that fibre does make a valuable contribution to the horse’s energy requirement. It is also important to distinguish between fibre and forage. Fibre is the nutrient found in lots of feed ingredients but is usually highest in forages. Forages also contain other energy sources such as sugar and so forage makes a significant contribution to the horse’s overall nutritional requirements as it should make up at least half of every horse’s ration.

FACT: Between 30-70% of a harder working horse’s energy requirements can be met with fibre!

The amount of energy supplied depends on the digestibility of the fibre, which is influenced by plant type, environmental conditions and most significantly maturity of the plant at harvest. The more mature a plant, the less digestible it will be and therefore the less energy it will provide.

The heat produced from fibre digestion also helps to keep the horse warm, hence why the advice is to feed plenty of fibre during the cold winter months to help keep your horse snug!

FAQ: Horses can’t digest fibre, can they?

Well not themselves no, but they do have a population of microbes in their digestive tract that can, and the energy the microbes release from fibre is what the horse uses as fuel for work, maintenance, or growth. The other key fact is that the horse’s digestive system is designed to slow the transit of fibre long enough for the microbes to break down the fibre and release the energy – if the horse’s gut was like ours, the bugs simply wouldn’t have time to do their work before the food passed through and out of the digestive system.

How much fibre should my horse have?

Whilst we don’t know the horse’s exact fibre requirement, the consensus is that horses should not have less than 1.5% of their bodyweight of forage on a dry matter basis daily, e.g – 7.5kg on a dry matter basis for a 500kg horse. Forages vary in their dry matter content; grass for example, contains about 80% water and so a horse has to eat a lot on an as fed basis to consume sufficient dry matter. Hay, in contrast, contains about 80% dry matter and wrapped forages such as haylage are somewhere in between!

High fibre ingredients – what are they and where do they come from?

There are a range of ingredients that are high in fibre that can be used in horse feeds and each one has different features and benefits. At Dengie, the sources we predominantly use are alfalfa, straw and dried grass, along with sugar beet pulp and pea hull fibre.

Alfalfa – is a highly digestible and nutritious form of fibre. It is naturally low in sugar and starch plus it is abundant in minerals such as calcium making it a superior buffer to acidity. Click here to learn more about feeding alfalfa to horses.

Grass – the digestibility of grass varies depending on the variety and the maturity at the time of harvest. At Dengie we use a blend of meadow grasses including tall fescue, timothy and rye. Dried grass is a source of naturally occurring sugar, just like fresh grass, which is why horses tend to find it palatable.

Straw – low in digestibility, calories and sugar, straw is a useful feed ingredient particularly for diluting more nutritious fibre sources to maximise chew time for good doers. Click here to learn more about feeding straw to horses.

Why feeding chopped fibre to your horse matters!

There are some fundamentals of feeding that stand the test of time and adding chopped fibre to a horse’s bucket feed is one of them. The increased chew time from adding a chopped fibre to the bucket feed has long been recognised but what is often over-looked is that the amount of saliva produced when a horse chews, is related to the amount of force the horse needs to apply (Vervuert, 2012). So more fibrous materials help to increase saliva production and therefore more natural buffering in the digestive tract than softer ones. Whilst mashes and pelleted fibres contribute fibre, they don’t require as much chewing and so do not generate as much saliva. This phenomenon is supported by a very recent study that found unmolassed sugar beet pulp mash resulted in a greater drop in pH (increase in acidity) in the horse’s mouth than other feed materials including alfalfa and haylage, which the authors suggest could be related to the fact it requires less chewing (Daniels et al, 2024). Whilst the level of acidity returned to normal within 15 minutes and so doesn’t represent a cause for concern in the context of dental health, it demonstrates the importance of chewing for saliva production which has benefits further along the digestive tract.

It is also important to consider that horses have evolved to graze but also browse on a variety of plant material consuming a range of materials from woody shrubs and trees (Clauss et al, 2023) and are more than able to cope with fibrous material. In fact, they often actively seek it out to satisfy their need for a diversity of fibre in their diets in the domestic environment. Studies have also shown that once horses have chewed forage, the average particle size is just a few mms long and so it is not sharp or stalky once it has been mixed with saliva and chewed.

High quality fibres such as precision dried grass and alfalfa can be extremely beneficial for performance horses as they not only provide fibre but are also relatively digestible and so do not sit in the digestive tract for as long as more indigestible forages such as straw, do. This helps to allay fears that there is more deadweight in the gut that requires the horse to expend more energy to move. In fact, some ground-breaking research is showing that switching the traditional ratios of cereals and fibre in the horse’s bucket feed doesn’t compromise performance and may have some metabolic benefits in addition to the obvious health ones. (Martin et al, 2023).

In contrast to grass forages, alfalfa is naturally low in sugar and starch, and with research showing that it is an effective natural buffer to acidity in the digestive tract, it is the ideal fibre source for maintaining gastric health. It also provides quality protein to help with building muscle and topline, and supplies plenty of slow-release energy for stamina.

My horse is a good doer and has plenty of forage, why do I need to add a chopped fibre to their bucket feed?

A key function of chopped fibre in the horse’s bucket feed is to slow the rate of intake. Whilst pelleted fibres and mashes supply fibre, they don’t perform the same important role of slowing the speed at which the horse consumes their feed. Recent studies have shown that even when relatively small amounts of feeds are fed as ‘meals’, as would be the case with a balancer, a horse with underlying insulin dysregulation experiences a more exaggerated insulinaemic response (Macon et al., 2022). Other studies have shown that feeding straw can slow the rate of intake to such an extent that no discernible insulinaemic response results (Jansson et al. 2021) which makes sense when we think about the basic principle of the horse being a trickle feeder. Slowing the rate of intake so the horse consumes a trickle of feed should therefore be the aim for all horses.

Does the type of fibre matter?

The type of forage also has an impact on consumption times and amount of chews too. Ellis et al., (2005), found the addition of chopped straw, at an inclusion rate of 20%, to a ration containing pellets and other chopped fibres resulted in significantly longer eating periods as well as an increased number of chews. This is in line with research by Dulphy et al., (1997) who found that straw is consumed significantly more slowly at 7.9g of dry matter per minute compared to hay at 14g per minute, so about twice as long!

Straw can be a very useful ingredient for good doers as it provides additional fibre and chew time in the ration while keeping the calories to a minimum. It can be a really useful way of bringing the calorie content of the forage portion of a horse’s diet down too.

Chopped straw fibre feeds count towards a horse’s total forage requirement and replacing just a couple of Kgs of hay with them can bring the total sugar intake down enough to make a difference. For example, Dengie Meadow Lite with Herbs is our ultra-low calorie feed providing just 5MJ/kg of digestible energy and is naturally low in sugar (3%) and starch (0.5%) – levels way lower than you would find even in Timothy hay. This makes it ideal for good doers and those prone to laminitis. It is a soft, tasty blend of high-quality oat straw with a very small inclusion of grass, cinnamon and thyme to help tempt fussy feeders. Pea hull fibre is included to provide some highly digestible fibre with postbiotics for added support for the gut microbiota.

For those worried about ulcers then Dengie Ulser Lite is a low calorie (8MJ/kg), sugar (6.5%) and starch (2%) fibre feed with added herbs, yeast and prebiotics to promote digestive health. It contains a blend of soft chopped grasses with high quality oat straw for maximum fibre content while still keeping the calories low. Alfalfa pellets are included for natural buffering due to their high levels of bioavailable calcium.