Daily rumination pattern recorded by an automatic rumination-monitoring system in pre-weaned calves fed whole bulk milk and ad libitum calf starter

The present experiment aimed to evaluate the potential of the Hr-Tag rumination-monitoring system (Hr-Tag; SCR Engineers Ltd., Netanya, Israel) to describe the variation in rumination activity behavior in pre-weaned calves from 2 until 35 days of age. The study was carried out in a commercial farm and involved 9 Italian Simmental calves (3 females and 6 males). All calves were provided ad libitum access to water and starter throughout the study and were offered 6 L of bulk whole milk/d from an open-bucket starting at day 2 from birth and through 5 weeks. The Hr-Tag system continuously recorded the rumination time (RT) by Hr-Tag loggers positioned on the left side of the neck, and data were summarized in 2-h intervals. RT recorded by Hr-Tag loggers increased (P < 0.0001) through the first 4 weeks, reaching a plateau at wk 5 and the pattern of daily RT was similar along the weeks. Around milk feeding the observed 2-h intervals of RT drastically decreased (P < 0.0001) compared to the 2-h intervals before. These data shed light on the daily pattern of rumination activity in pre-weaned calves, showing a distinct daily behavior, as observable in adult cattle. Data of this study support the use of the Hr-Tag system for studying rumination activity behavior in the pre-weaning phase of calves.