Table 1.

Descriptions of the evaluated behavioural activities. Adapted from Raspa et al. [20].

Behavioural Activities	Descriptions
Self-grooming	The horse cleans its body by shaking its entire body or a part of it, nibbling or licking the coat hair, rolling on the ground, or rubbing parts of the body against objects or other parts of the body (e.g., rubbing the muzzle against the limbs)
Mutual grooming	Body cleaning is performed reciprocally, or by one horse towards a conspecific
Lying	The horse is lying on the ground in the sternal position or in lateral position
Playing	The horse plays alone or with other horses. It includes: play with structural parts of the pen, sexual play, locomotor play, and play fighting
Locomotion	The horse moves inside the pen by taking steps; the neck is in a horizontal position or lowered to the ground to sniff
Feeding	The horse eats hay, straw, or feedstuff in the trough or on the ground
Drinking	The horse drinks
Standing	The horse is in a quadrupedal station. The expression is relaxed (standing relaxed) or attentive (standing alert)
Snaking	The horse stretches its neck towards a conspecific with the ears turned backwards, threatening to bite
Kicking	The horse lifts one or both hind limbs off the ground and quickly stretches it/them towards a conspecific
Biting	The horse quickly opens and closes its mouth, and its teeth touch the body of a conspecific. Its ears are turned backwards
Sexual behaviour	The stallion sniffs or bites the female’s genitals. Or the stallion mounts the female: erection and penetration are present
Stereotypic behaviour	The horse expresses a stereotyped behaviour: both oral and locomotor stereotypes are considered