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

SIMPLE SUMMARY: The keeping and use of horses have become of increased interest to the public due to welfare concerns. It is therefore vitally important to better understand the impacts on the horse’s emotional state and how to measure and use observed behaviours to determine the effects of common husbandry practices on the horse. This will enable steps to be taken to improve equine quality of life and ensure the social licence to operate within the horse industry. In order to achieve this, reliable animal-based behavioural indicators of welfare that can be used in industry are needed. The behaviour of horses kept on day-stabling routines was compared to that of horses kept on night-stabling routines. Eight behaviours including ear movement and locomotory leg movements as well as yawning, recumbency, and non-nutritive chewing occurred significantly more often in horses on a night-stabling routine. These behaviours have been identified as potential indicators of affective state (the animal’s underlying emotional state) and equine welfare that can be used in dynamic quality of life assessments. ABSTRACT: 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; t(7) = 5.70; p = 0.0004). Eight behaviours occurred significantly more often during NS than DS: forward ears (t(7) = 3.32; p = 0.001), neutral ears (t(7) = 3.47; p = 0.001), stepping forward (t(7) = 2.62; p = 0.001), stepping laterally (t(7) = 2.39; p = 0.001), sternal recumbency (t(7) = 2.64; p = 0.001), yawning (t(7) = 2.69; p = 0.001), non-nutritive chewing (t(7) = 2.49; p = 0.001), and closing eyes (t(7) = 2.71; p = 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.