Sleep vs. no sleep; equine nocturnal behaviour and its implications for equine welfare

Sleep is well recognized as an important facilitator of physical well-being and optimal mental functioning. Providing nocturnal environments that promote sleep should therefore be considered a key responsibility of human care givers for animals managed within artificial settings. Stabling is a convenient and widely used method of managing the domestic horse, with a number of human-perceived benefits for the horse. Evidence exists, highlighting how instrinsic diurnal behavioural patterns are limited due to this type of management, including grazing, social interaction, and free-movement. This abstract outlines a series quasi-experimental and observational studies completed over the last five years, which describe and provide insight into equine nocturnal behavioural patterns. All studies employed focal continuous sampling methods and involved the use of infrared CCTV systems. These studies conform to ISAE Ethical Guidelines, with ethical approval gained from the Hartpury Ethics Committee. Results highlight that nocturnal behaviour is indeed affected by a range of factors linked to stabling. In the first study published in 2013, duration of nocturnal recumbent and ingestive behaviours were recorded from 7pm to 7am for stabled horses bedded on either wood shavings (n=5) or straw (n=5). Differences between groups were analysed using Mann Whitney-U and although non-significant (p>0.05), horses bedded on straw spent a greater propotion of the nocturnal behavioural time budget recumbent (29%) compared with horses bedded on shavings (12%). Stable designs enabling social interaction through the use of barred instead of brick walls are generally considered an example of good welfare. After observing twelve horses for two consecutive nights between 10pm and 7am, significantly less (t=2.436, P<0.05) standing sleep was recorded for horses stabled in solid walled, and although non-significant a greater proportion of time was spent recumbent compared to horses in barred wall stables. Ten horses observed for a total of four non-consecutive nights between 7pm and 7am, following the move from overnight turnout to overnight stabling demonstrated an acclimatization period through a significant increase (P<0.01) in duration of recumbent behaviour from the first week of stabling (5% of the time budget) to six weeks later (16% of the time budget). A preliminary study investigating whether sleep-related behaviours impact upon subsequent ridden performance found a positive correlation (R2 = 0.513) between competition performance and average duration of nocturnal recumbent behaviour. Anecdotally horse owners may not consider what the horse does whilst stabled overnight, with assumptions about the occurrence of sleep. This collection of studies highlights how husbandry practices may be (re)considered to facilitate sleep-related behaviours. Moreover, although tenuous, links to performance are also evident, therefore next steps might involve determining specifically how lack of sleep manifests within diurnal equine behaviour.