Pasture and forage are naturally the primary sources of fibre in a horse's diet. However, there are also feed ingredients that are significant sources of fibre and offer higher energy density than traditional forages, with a greater proportion of digestible fibre—these are known as "super fibres."
The energy density of super fibres is lower than that of cereals (e.g., corn, barley, and oats), and due to their fibrous nature, they do not carry the risks associated with excess starch intake. As such, they are considered a safe way to provide extra energy while supporting gut health.
Super fibres are often included in complementary compound feeds ("ration"), contributing to the fibre content of these feeds. They are particularly present in commercial products marketed as “high-fibre” or “cereal-free.” In the latter, with the absence of cereals, fat also plays a key role in providing energy.
Super fibres can also be used to complement forage and regular concentrate feed, and are especially useful in the following scenarios:
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To complement low-digestibility hay.
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When there is a need to increase energy intake without raising starch levels (e.g., when concentrate consumption is already high or in horses particularly sensitive to starch, such as those with gastric ulcers or predisposition to myopathies).
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In horses with dental problems, such as geriatrics, who struggle to consume adequate amounts of pasture/forage.
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In horses that have difficulty maintaining adequate body condition.
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In horses undergoing prolonged exertion (such as in endurance), these fibres provide energy and also help retain water in the extravascular space, allowing the intestine to act as a reservoir for water and electrolytes.
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Among other uses.
Most Commonly Used Super Fibres
The most widely used super fibres in equine nutrition are beet pulp and soy hulls. Less common types include almond hulls or citrus pulp, which, while offering good fibre digestibility, tend to have low palatability for horses.
Beet Pulp
Beet pulp has a high content of digestible fibre (about 85% of its fibre is digestible), is low in starch, and is considered relatively low in sugar (about 10%). Its protein content varies (between 8–12%), similar to that of good grass hay, and it has a relevant calcium level, though lower than that found in, for example, alfalfa.
Despite these benefits, beet pulp is not recommended as a forage substitute, but rather as a complementary ingredient. It is rapidly fermentable, mainly composed of digestible fibre, and relatively low in other nutrients provided by forage (e.g., vitamins and other minerals).
Soy Hulls
Soy hulls are frequently included in concentrate feeds to increase fibre content, offering highly digestible fibre (around 75%). They are less commonly used as a standalone supplement alongside hay and concentrate feed, less often sold in pelleted form for end consumers, and generally have lower palatability.
Other Fibre-Contributing Feeds
Wheat Bran
Wheat bran is a common component of concentrate feeds. However, its actual fibre content is often overestimated, providing only 10–12% crude fibre (in contrast to about 20% in beet pulp). When used alone in addition to forage and concentrate, wheat bran presents some drawbacks:
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It is high in phosphorus and low in calcium, resulting in an inverted calcium-to-phosphorus ratio (the ideal Ca:P ratio in horse feed should be 1.5 to 2:1). This is corrected in commercial feeds through calcium supplementation. When used independently and without proper formulation, it can lead to orthopaedic problems in growing animals, nutritional secondary hyperparathyroidism, among other issues.
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Its starch content is not negligible, ranging between 15 and 20%.
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Raw, unprocessed wheat bran often has poor microbiological quality.
Alfalfa
Alfalfa is another high-quality fibre source. While the digestible fibre content of alfalfa varies, as with any forage, it is a solid option, with significant protein and calcium content.
Key Takeaways:
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Fibre sources with high digestibility and greater energy density than forage are commonly referred to as “super fibres.”
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The use of super fibres allows for:
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Complementing low-quality hay,
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Increasing energy intake without raising starch,
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Providing digestible fibre for horses with dental issues,
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And supporting performance horses in demanding disciplines.
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