Comparison of two tri-axial accelerometers for measuring locomotor activity in ewes and lambs

Abstract

Triaxial accelerometers provide a non-invasive means of recording all small-scale body motions of an animal. The summary metrics that can be extracted from a given accelerometer, and the validity and reliability of the estimates obtained, determine whether a particular accelerometer is suitable for research. The objectives of this study were to compare the performance of two models of triaxial accelerometers in quantifying the behavior of adult ewes and growing lambs, and to compare the circadian rhythms calculated from the locomotor activity data collected by these accelerometers. Ten non-pregnant ewes, and 10 weaned lambs, which were in their fattening period were used in experiment 1 and 2, respectively. Ewes and lambs were fitted with two models of commercially available accelerometers (ActiGraph wGT3X-BT and Axivity AX3), which were attached to a neck collar that remained in place for 10 d The profiles of the mean locomotor activity of ewes and lambs based on the two devices were similar. In addition, the cosinor curves of the two devices fit each other, and their acrophases did not differ significantly. Both accelerometers indicated that all ewes and lambs had a 24 h rhythm in locomotor activity. The coefficient of correlation and the coefficient of determination between the Actigraph and the Axivity data were 0.798 (P < 0.01) and 0.6369 (P < 0.01), and 0.940 (P < 0.01) and 0.8843 (P < 0.01), for ewes and lambs, respectively. Given the strong correlations between the Actigraph and the Axivity tri-axial accelerometers in quantifying the activities of ewes and lambs, and the similarity of the circadian rhythmicity curves calculated from data from the two devices, both brands of accelerometers are suitable for measuring the locomotor activity in these animals.

Keywords

• Sheep
• Accelerometer
• Locomotor activity
• Circadian rhythm