Joan-Bryce Burla

Space Allowance of the Littered Area Affects Lying Behavior in Group-Housed Horses

Horses can sleep while standing; however, recumbency is required for rapid eye movement (REM) sleep and therefore essential. Previous research indicated a minimal duration of recumbency of 30 min per 24 h to perform a minimal duration of REM sleep. For group-housed horses, suitable lying area represents a potentially limited resource. In Switzerland, minimal dimensions for the space allowance of the littered area are therefore legally required. To assess the effect of different space allowances of the littered area on lying behavior, 38 horses in 8 groups were exposed to 4 treatments for 11 days each; T0: no litter provided, T0.5: 0.5× minimal dimensions, T1: minimal dimensions, and T1.5: 1.5× minimal dimensions. Non-littered areas were covered with hard rubber mats. Lying behavior was observed during the last 72 h of each treatment. The total number of lying bouts per 24 h was similar in treatments providing litter, whereas in treatment T0, recumbency occurred only rarely (F1,93 = 14.74, p = 0.0002) with the majority of horses lying down for less than 30 min per 24 h (χ12=11.82, p = 0.0006). Overall, the total duration of recumbency per 24 h increased with increasing dimensions of the littered area, whereby the effect attenuated between treatment T1 and T1.5 in high-ranking horses but continued in low-ranking horses (F1,91 = 3.22, p = 0.076). Furthermore, low-ranking horses showed considerably more forcedly terminated lying bouts in treatments T0.5 and T1, but were similar to high-ranking horses in T1.5 (F1,76 = 8.43, p = 0.005). Nonetheless, a number of individuals showed durations of recumbency of less than 30 min per 24 h even in treatment T1.5. The lying behavior was dependent on the availability of a soft and deformable surface for recumbency. A beneficial effect of enlarged dimensions of the littered area was shown by increased durations of recumbency and decreased proportion of forcedly terminated lying bouts in low-ranking horses. Taking this into account, it became evident that the minimal dimensions for the littered area as implemented in the Swiss animal welfare legislation do not ensure undisturbed lying behavior for all members of a given group.

Effects of feeding management and lying area on the behaviour of group-housed horses

The observation of locomotor activity and resting behaviour is used to determine time budgets, which may give some indication for the assessment of horses’ welfare concerning management and housing. As an alternative to time-consuming direct observations, a common automatic measuring method is the use of pedometers. One disadvantage of pedometers is the loss of information due to pooling of data, which also disallows the distinction of different gaits. In this study, the suitability of an accelerometer (MSR145 data logger) for automatic gait determination was tested. The aims of the study were to define acceleration value ranges for stand, walk, trot and gallop and to compare acceleration data with a commonly used pedometer (ALT-Pedometer). For the validation, 20 horses of different breeds and height at withers were all exercised in stand, walk, trot and gallop for 5 min each with both measuring devices attached to the left foreleg. Acceleration of the vertical leg movement was measured at a sampling rate of 10 Hz. Acceleration data was calculated per second and averaged over the entire 5 min interval to obtain acceleration values. Steps measured by the pedometer were accumulated during minimum sampling intervals of 1 min. For gait determination, breed classes Horse (> 148cm), Pony ( 148cm) and Icelandic horse were analysed separately. Results revealed a significant influence of gait on mean acceleration values without overlap between the different gaits, when Icelandic horses were considered separately from other horses and ponies. Therefore, data allowed the determination of gaits by definition of distinct acceleration value ranges for stand, walk, trot and gallop. A positive correlation between acceleration values measured by MSR145 data logger and step activity measured by ALT-Pedometer was found for stand and walk; trot and gallop could not be distinguished by the pedometer. The validation revealed a clear suitability of the MSR145 accelerometer for gait determination in horses. The MSR145 was shown to be a high-precision measuring device that appeared to be an advantageous alternative to pedometers for measurements of locomotor activity in horses.