Horses are herbivores and are designed to eat a diet high in fibre and low in starch, obtained through freedom of movement to select and forage from a diverse range of plants in the company of other horses. Forage fed to domesticated horses is often provided in various devices designed to replicate more natural feeding patterns, but can result in frustration behaviours even though horses are adept at learning to manipulate such devices to surmount feeding challenges. Because domesticated horses are often required to perform in a range of spheres, which in turn requires higher energy output, many horses have their fibre rations restricted in favour of feeding high-starch substrates. This can lead to significant changes in the microbial environment of the gut, which compromises gastrointestinal health and can cause a range of undesirable behaviours. Diet-related disorders such as gastric ulcers are commonly seen when restricting forage rations and/or overfeeding starch in the horse, and behavioural consequences include frustration-related behaviours, aggression and oral and locomotory stereotypies, all of which compromise the horse's welfare. Meeting the behavioural needs of the horse by giving them agency to access the 3 Fs – friends, forage and freedom – is inextricably linked with their natural feeding behaviour. It is fundamental to ensure that horses are provided with the opportunity for positive feeding experiences to improve both physical and mental welfare.