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 behavioral 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 behavior. 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 behavior was 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), exposure to music for five nights (Beethoven's ninth Symphony) played at an average of 62.3 decibels (phases B1 [nights 3-4] and B2 [nights 6-7]), and two further nonconsecutive nights (phase A2) when music was no longer played. A general linear model was used to determine differences in the frequency of parametric behavioral data with a significantly higher occurrence of ingestion (F [3,18] = 7.910, P = .001) during phases in B compared with A, and a significant decrease in the occurrence of other behavior (F [3,18] = 10.25, P = .000) comparing phase Al with all other phases. The Wilcoxon signed rank test highlighted significant differences in the frequency of lateral recumbency between specific phases (P < .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. (C) 2019 Elsevier Inc. All rights reserved.