A Preliminary Study Investigating the Influence of Auditory Stimulation on the Occurrence of Nocturnal Equine Sleep-Related Behavior in Stabled Horses

The physical environment is known to influence nocturnal behavioural time budgets of the stabled horse, but less evidence exists to suggest how this might be affected by including additional sensory stimuli. This study aimed to establish the impact of novel auditory stimuli on the frequency of equine sleep-related behaviour. Seven horses stabled for 24 hours per day on the same yard receiving the same daily management routine were observed from 2030 to 0630 over nine nights. Frequency of nocturnal behaviour were recorded using focal intermittent sampling against a predetermined ethogram and an infrared CCTV camera system. Data were recorded under the following conditions: without music for two nights (phase A1), five nights exposure to music (Beethovens’ 9th Symphony) played at an average of 62.3 decibels (phases B1 [nights 3-4] & B2 [nights 6-7]), and two further non-consecutive nights (phase A2) when music was no longer played. General Linear Model was used to determine differences in the frequency of parametric behavioural data with a significantly higher occurrence of ‘ingestion’ (F[3,18]=7.910, P=0.001) during phases in B compared with A, and a significant decrease in the occurrence of ‘other’ behaviour (F[3,18]=10.25, P=0.000) comparing phase A1 with all other phases. The Wilcoxon Signed Rank highlighted significant differences in the frequency of ‘lateral recumbency’ between specific phases (P<0.05). The addition of music appears to have a significant effect on the equine nocturnal time budget that might be beneficial from an equine sleep perspective.