REST AND ACTIVITY CONDITION RECORDED IN HORSES BY USING TWO DIFFERENT ACCELEROMETER DEVISES

Rest activity represents a component of the physiological activities encompassed by total locomotor activity (TLA), which includes conscious and unconscious motions and is influenced by different factors such as photoperiod, stabling conditions, feeding schedules or exercise (1). The present study evaluated rest activity as part of the locomotor activity in horses through the use of two different accelerometer devices (Actiwatch-Mini system and SENS motion). Actiwatch-Mini device includes different behaviors, such as feeding, drinking, walking, grooming, and small movements during sleep/rest. The SENS motion device monitor TLA by splitting movement in different categories according to intensity and devise position, identifying rest activity as the hours each animal spent lying down in a state of immobility (lying/sitting rest). Ten Italian clinically healthy saddle horses were enrolled in the study and divided in two groups according to their sport activity. Group A (n=5) consisting of 3 nonpregnant females and 2 geldings (10±3 years old) were stabled in boxes undergoing weekly training. Group B (n=5) consisting of 2 non-pregnant females and 3 geldings (12±2 years old) were housed in paddock during daytime and in boxes during nighttime, not subjected to training. TLA was simultaneously monitored for 48 consecutive hours using both devices. Data collected were averaged at five-minute intervals. A factorial analysis of variance ANOVA was applied to Actiwatch-Mini raw data and on the lying/sitting rest category obtained with SENS motion devise to investigate the effect of day and group. The Bland-Altman test was performed to assess the agreement of the intensity of the movement recorded with both techniques. Significant effect of group (p<0.0001) and day (p<0.0001) was obtained in both measurements. Post hoc comparison test showed a significantly greater number of rest hours during day 1 compared to day 2 (p<0.0001) in Group A recorded with both techniques. No differences between days were observed in group B using SENS motion (p=1) and Actiwatch-Mini (p=0.2). A significant greater number of rest activity hours was shown in group A than group B (p<0.0001) with both measurements. Bland-Altman test showed an agreement between both technique values in group A during day 1 (Bias: 202.3 ranged from -86.77 to 491.4) and day 2 (Bias: 101.9 ranged from-101.1 to 304.8) and in group B during day 1 (Bias 159.2 ranged from -70.16 to 388.6) and day 2 (Bias: 180.7 ranged from -60.28 to 421.7) as all data fell within the upper and lower limit of agreement. The difference in groups was not an index of variation in the quality of rest, which instead was more likely to be influenced by physical activity. These results suggest that, in the context of management of athletic horses, it is critical to always maintain adequate time and space for rest in order to promote recovery, reduce the risk of muscle overload, and ensure welfare (2). An overlap of the results obtained through the different measurement techniques can be observed. In particular, SENS motion device could be a viable replacement for the classic assessment of TLA by taking into account different classifications of movement and intensity, providing an equal but more precise and specific assessment of rest activity.