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Abstract: By limiting our horse's freedom of movement, we restrict their opportunity to forage, which is one of their most important needs. If their need of forage is not fulfilled it can lead to frustration, which might manifest itself in abnormal behaviour, like the oral stereotypies for example crib-biting. It is a held belief that the horse swallows air while crib-biting, which they don't, and that swallowed air causes colic, and the belief that other horses can copy the behaviour, leads to the use of many methods to prevent the behaviour. Cribbing-collar, operations, electrified ledges and bad tasting solutions are methods to prevent the performance of crib-biting. As new studies indicate that the function of the behaviour is to ameliorate underlying problems, the methods can do more harm than good and decrease welfare. Methods used often address symptoms rather than underlying causation. There are many theories about why horses crib-bite. According to the so called "theory of coping", stereotypies has the function of handling frustrating situations without ending up in long duration state of stress. Research work shows that time spent in the stable is correlated to development of stereotypic behaviours. Small amount off fibre diets, high concentrate rations and bedding types other than straw increase the risk of developing crib-biting. Crib-biting is thought to keep a normal gastrointestinal activity when there is little to forage. Horses are adapted to feed during a large part of both day and night in contrast to modern housing systems where the horses often are given food only a few occasions during the day. The time is often long between night and morning feedings and therefore the stomach is empty long times. Since there always is a continuous secretion of acetous, corroding gastric juice, the walls of the stomach might suffer when the stomach is empty. It can lead to gastric ulcer, which might be the cause of crib-biting. Crib-biting is thought to increase salivary secretion. Equine saliva is a natural buffer but is produced only during mastication. Horse owners often use shavings or peat litter, mostly due to practical reasons, even though horses forage more on straw-bedding. The aim of this study was to investigate if the frequency of crib-biting changes with the use of straw bedding, instead of shavings or peat litter. The result showed, contrary to the hypothesis and earlier studies, that the frequency of crib-biting in crib-biting horses increased to begin with, when straw bedding was used. As crib-biting and forage seems to act together, crib-biting increased when there was more opportunity to forage, as comes with straw-bedding instead of shavings or peat litter. The result might support the theory that crib-biting horses not produce enough saliva and that crib-biting increase the production.