Technical Note: Evaluation of an ear-attached movement sensor to record rumination, eating, and activity behaviors in 1-month-old calves

Sixteen male Holstein calves were fitted with ear-attached motion sensors to evaluate the sensor's (3-dimensional accelerometer with algorithms to process the collected data, CowManager SensOor, Agis, Harmelen, the Netherlands) ability to record rumination, eating, and activity behavior compared with scan sampling by trained observers. Before and after weaning, Holstein calves were in individual pens fed milk replacer with free-choice textured starter and water. Three trained observers used live observation to evaluate individual calf behaviors (Table 1). Instantaneous recording was applied at 1-min intervals (5 to 10 s/calf each min) for 12 h/d on 4 different days. Observation periods included after the morning milk replacer feeding; midday; and just before, during, and after the evening milk replacer feeding. Data were analyzed with regression and ANOVA methods, with significance declared if P ≤ 0.05. Behavior scoring did not differ among the 3 individuals. Relationships of sensor versus observed times were not significant (R2 <0.3) in 4-wk-old calves; however, changes were made to sensor placement in ear, and face fly irritation of calves for reevaluation. In wk 6 around the time of weaning, simple regression analysis of sensor versus observed rumination (R2 = 0.91), eating (R2 = 0.75), and not active (R2 = 0.97) times had y-intercepts that did not differ from zero and significant slopes. Sensors were a valid measurement tool for rumination, eating, and inactivity times in 6-wk-old calves, but ear placement and environmental conditions discussed are critical for success.