Triaxial accelerometers for recording grazing and ruminating time in dairy cows: An alternative to visual observations

Abstract The aim of this study was to validate the recordings of a commercial triaxial accelerometer (HOBO Pendant G data loggers) with respect to visual observations of grazing and ruminating time of dairy cows. Seven lactating Holstein cows with a mean body weight of 602 ± 45 kg were used for the study. Grazing and ruminating times were recorded using HOBO loggers (31.5 hours of total observations for grazing and ruminating) that were attached to the lateral-medial side of the jaw using a strap attached to the head of each cow in a position such that the X-axis was parallel to the ground, the Y-axis was perpendicular to the ground pointing upward, and the Z-axis was parallel to the ground pointing away from the sagittal plane; these relative positions were defined when the cow was in a natural head-up position. Median acceleration (m/s 2 ) readings in the X-axis >0.175 and −0.275 and 0° and 0° and P P > 0.05) for estimating ruminating time. When acceleration and tilt were used for estimating grazing (X- and Y-axis) and ruminating (Z- and Y-axis) time, the slope in both showed a significant ( P ≤ 0.001) relationship. The prediction R 2 in both activities indicated that acceleration (X- and Z-axis) and tilt (Y-axis) of HOBO loggers explained 0.961 and 0.945 of the variance in visual observations per cow/day. Therefore, the validation of the HOBO loggers was successful on a per cow/day and per day basis.