Table 1.

Behaviour sampling ethogram used to measure the frequency of selected behavioural events during confinement or transportation. Total stress-related behaviour was calculated summing the frequency of all behavioural events related to stress. Total balance behaviour was calculated summing the frequency of all behavioural events related to balance. Total behavioural events were calculated summing the frequency of all the single behavioural events.

Behaviour	Description
Behavioural events related to stress (Expressed as frequency) (n/20 min)
Biting neighbour	The horse bites the neighbour
Explorative behaviour/sniffing	The horse sniffs around, it sniffs some area of the truck/box
Head Surveying	Head scanning through forty-five degrees or more, ears pricked up pointing forwards and stationary for 3 s or more (adapted from [26])
Head tossing/shaking	The horse shakes its head suddenly, violently and frequently [5]
Chewing/licking	Opening of mouth with extension and retraction of tongue, lip smacking without tongue extension, lateral jaw movements involving partial opening of the lips [27]
Licking the truck/wall	The horse licks part of the truck/box (wall, stall rails)
Pawing	One front leg is lifted from the ground slightly, then extended quickly in a forward direction, followed by a movement backward, dragging the toe against the floor in a digging motion [28]
Scratching	Rubbing any part of the body against part of the stock/truck (Adapted from [26]
Stereotypy	The persistent repetition of a behaviour for no obvious purpose [27]
Touching tie cord	The horse touches the rubber cord with which he is tied [5] in the truck or in the stocks
Turning the head	The horse turns his head and neck to the right or to the left appearing to look at his flank
Total stress-related behaviours	Sum of the behavioural events related to stress
Behavioural events related to balance (Expressed as frequency) (n/20 min)
Backward movements	The horse steps backward
Forward movement	The horse steps forward
Lateral movements	The horse steps sideways
Leaning on stall rails	The horse gently leans laterally against one of the two stall rails of the stock or of the bay
Loss of balance/dashing on the partitions	The horse losses his balance and crashes/bumps on one stall rails
Total balance-related behaviours	Sum of the behavioural events related to balance
Other behavioural events (Expressed as frequency) (n/20 min)
Interaction with neighbours	The horse interacts with one of his neighbours through the stall rails, they sniff each other
Stand on three limbs	The horse is standing on 3 or 4 limbs without moving in any direction [29]
Body stretching	Rigid extension of the limbs and arching of the neck and back [26]
Yawning	An involuntary sequence consisting of mouth opening, deep inspiration, brief apnoea, and slow expiration [30]
Total behavioural events	Sum of all behavioural events