The Effect of Stabling Routines on Potential Behavioural Indicators of Affective State in Horses and Their Use in Assessing Quality of Life.

Increasing interest in equine welfare has emphasised the need for objective and reliable behavioural indicators of horses' affective state. However, research has yielded mixed results regarding behaviours suited for industry use largely because they are subject to anthropomorphic interpretation. Stabling is commonly used to manage domesticated horses despite research indicating that it can negatively impact horse welfare, but its effect on their affective state is yet to be quantified. Ten adult horses (11.8 ± 4.4 years) were observed either on a day- (DS) or night-stabling (NS) schedule over two consecutive 24 h periods. NS horses were kept confined for significantly longer (13.60 ± 0.04 h) than DS horses (7.73 ± 0.07; = 5.70; = 0.0004). Eight behaviours occurred significantly more often during NS than DS: forward ears ( = 3.32; = 0.001), neutral ears ( = 3.47; = 0.001), stepping forward ( = 2.62; = 0.001), stepping laterally ( = 2.39; = 0.001), sternal recumbency ( = 2.64; = 0.001), yawning ( = 2.69; = 0.001), non-nutritive chewing ( = 2.49; = 0.001), and closing eyes ( = 2.71; = 0.001). These behaviours may be candidates for indicators that can be used to determine the affective state in horses and subsequently be used to assess equine quality of life and to optimise individual horse welfare.