Horses eating wood isn’t an uncommon phenomenon. In some stables, one might think that beavers are present instead of horses: The tying beam is merely a shadow of its former self, and the walls in the open yard show extensive gnawing. The supporting beams of the stable roof have been eaten away to a minimal load-bearing level… What could be causing all this?
When horses are hungry…
First and foremost, one should check if the horses are receiving enough roughage.
Feeding them in intervals with long breaks (“to prevent excessive weight gain”), overcrowded open yards with more horses than feeding places (“musical chairs feeding”), or the practice of keeping horses in single stables without any hay feeding during winter days (“they can eat inside the entire night”) might lead to horses eating everything out of sheer hunger. Apart from wood, they might also consume earth, sand, or faeces.
Let us assume that the horses are being kept and fed in a manner that suits their natural needs. Even in well-fed domestic horses, just like their wild counterparts, wood in the form of branches, twigs, bark, or roots is a normal part of their diet.
Living conditions during the horse’s youth can play a role
The requirement for wood consumption may vary slightly from breed to breed and also from horse to horse, often influenced by their feeding habits during their upbringing. Horses from Spain, for example, often have a higher demand for wood fiber and may even consume all their straw bedding.
Their upbringing in the arid regions of Spain exposes them to a diet rich in wood fiber. This is in stark contrast to warm-blooded horses from the marshlands of Frisia.
Unlike cellulose, wood fiber does not significantly contribute to energy production. It serves as dietary fiber, passing through the digestive system mostly unchanged. Nevertheless, it is vital in a diet appropriate to their species.
The digestive system’s role is to break down food components and absorb them through the intestinal wall, making them available to the metabolism. Therefore, much importance is given to the nutrient content when calculating feed rations.
Dietary fibers are often underestimated
Dietary fibers, on the other hand, often go unnoticed, even though they play a crucial role in enabling proper nutrient utilisation. They are (largely) indigestible components of food, but their structure stimulates and regulates intestinal motility, or peristalsis.
The food bolus needs to be transported at the right pace—neither too fast nor too slow—so that food components can be properly broken down and made available to the body.
For humans, almost all types of fiber are considered dietary fibers, such as pectins, cellulose, hemicellulose, and also lignin (wood fiber). In horses, however, most fibers can be digested in the large intestine by the symbiotic bacteria located there.
Wood fiber, on the other hand, is almost indigestible for horses, acting as pure dietary fiber. When added to their feed in the correct amount, wood fiber ensures proper movement of the food bolus. It mustn’t move too fast, as that could hinder the extraction of nutrients and water.
Thus, eating wood fiber is entirely natural for horses, whether from bushes or trees in their surroundings, which they happily “trim,” or nibbling on stable structures when other sources of wood fiber are unavailable.
Bark also has benefits
Furthermore, it’s observed that horses are adept at peeling off and consuming bark from trees and bushes, as well as from branches and twigs provided to them. Bark often contains bitter substances that also regulate peristalsis. Moreover, many plants contain active substances in their barks, such as the well-known acetylsalicylic acid in willow bark, which acts as natural pain relief. Additionally, barks contribute to mineral and trace element intake, much like the foliage, which horses also eagerly nibble on.
Leaves provide minerals, trace elements and humic acids in addition to fiber
When taking a walk in the forest, one might observe horses not only nibbling on branches but occasionally digging out and eating leaves from under the snow. Apart from the fiber content, foliage provides many minerals and trace elements. Additionally, in the winter time, leaves are often slightly decomposed, containing a high proportion of humic acids.
It is believed that humic acids regulate the intestinal environment and can counteract faulty fermentation processes. Furthermore, they appear to be able to bind glyphosate, which horses might ingest through straw or hay harvested near grain fields.
Tooth abrasion may also lead to gnawing on wood
The fact that many horses tend to gnaw on wood more towards the end of winter could have another reason than just intestinal regulation. Unlike grazing, eating hay does not sufficiently wear down horses’ incisors. Despite the lack of wear, the incisors continue to push further out of the jaw.
Over time, this may lead to the molars not aligning correctly during the grinding process, making it increasingly difficult to chew hay.
During February or March, it’s often observed that horses gnaw on wood using their incisors, sometimes without even consuming the wood.
Presumably, they are trying to achieve a certain level of tooth wear, enabling a more efficient chewing process. Conducting a scientific study to confirm this hypothesis would be intriguing.
Conclusion:
Horses consuming wood fiber in the form of twigs, bark, leaves, and straw, and occasionally even gnawing on stable equipment, is entirely normal. As such, they appreciate it when owners bring along branches and twigs from walks in the forest. You can also provide them generously with pruned branches from non-toxic trees such as fruit trees or willows.
However, it is essential to ensure they do not gnaw on treated wood, as that of stable buildings, fence posts, old railway sleepers, or former telephone poles used as tying beams. The wood preservatives used in these cases are anything but healthy.
