This dataset contains sensor data collected from 10 multiparous Holstein cows fitted with Axivity AX3 sensors mounted on neck collars. The cows were monitored during pasture access periods (07:30–14:00 daily) over a three-week period in April 2024 at ILVO (Melle, Belgium). Accelerometer data were sampled at 12.5 Hz and processed using a supervised decision-tree classifier developed for resource-constrained environments. Behavioral classifications include grazing and ruminating activities. The dataset supports real-time in-situ classification and provides a foundation for developing edge-based livestock behavior monitoring tools.