The act of rumination

Abstract

1. A detailed analysis was made of the rumination behaviour of one caged sheep on four combinations of diet, ranging from 100% hay to 100% concentrate meal.2. When hay was fed there was no relationship between the quantity of it ingested and the amount of rumination, which averaged 8 hr. daily. When concentrates were fed alone rumination time fell to 2½ hr. per day and much of this was ‘pseudorumination’.3. Evidence is produced to show that the number of chews and not the time chewing is the accurate way of measuring rumination quantitatively. This particular sheep made an average of 39,000 rumination chews per day when hay was fed.4. The duration of the intervals between boli was constant at 15% of total rumination time, but the rate of chewing varied from 83–99 chews per minute, being slower during the midnight to noon half of the 24 hr., when most rumination occurred.5. Rumination periods last from under 1 min. up to about 2 hr.6. Tiring during a rumination period was reflected by an increase in the intervals between boli but the number of chews per bolus remained unchanged.7. The first bolus of each period of rumination was chewed less than those following. This sheep averaged fifteen periods of rumination per day, a daily total of 500 boli were regurgitated. There were 2500 chews per period and seventy-eight chews per bolus.