RESUMEN
BACKGROUND: Eating and rumination variables were recorded in 300 healthy lactating dairy cows of 3 different breeds (100 Brown Swiss, 100 Holstein-Friesian, 100 Swiss Fleckvieh cows). Eating and rumination variables were monitored during a 24-h period using an automated system that recorded jaw movements via a pressure sensor integrated into the noseband of a halter. Phases of eating and rumination were reliably identified in the recordings based on typical patterns seen in previous studies. The variables analysed included duration of eating and rumination, number of chewing cycles during eating and rumination, number of regurgitated cuds and number of chewing cycles per cud. RESULTS: The cows ate for an average of 265 ± 54 min and chewed 17,077 ± 3646 times per day. The duration of rumination was 441 ± 71 min, there were 578 ± 94 cuds per day and 55 ± 10 chewing cycles per cud. There were significant correlations (P < 0.01) between duration of eating and number of chewing cycles during eating (r = 0.94), between duration of rumination and number of chewing cycles per regurgitated cud (r = 0.56) and between duration of rumination and number of regurgitated cuds per day (r = 0.53). CONCLUSIONS: The eating and rumination variables established in the present study reflect the current conditions of Swiss dairy farming and serve as reference intervals for assessing sick cows.