This experiment was conducted in order to examine the effect of fasting on rumination activity in sheep. The experiment consisted of two trials, in which the sheep were fasted for 2- and 3-days in trials 1 and 2 respectively. Two sheep were given an orchard grass hay twice a day during consecutive seven days prior to the fasting. Each trial was designed to impose one refeeding day between two fasting periods.
Ruminating behaviour was measured on last two days in preliminary feeding period and then continuously measured on every day until the final day of experiment.
Using a pen-writing recorder joined with strain amplifier and wire resistance strain gauge connected under the jaw of an experimental animal, rumination behaviour was recorded.
The rumination time distinctly declined just after the beginning of fasting, and the rumination time on the first, 2nd and 3rd days of fasting fell to 27-39, 19-23 and 15 % respectively, as compaired with that when sheep were fed normally. The rumination time recovered at once, on the day when sheep was fed hay again after fasting for 2-day, but not completly recovered after fasting for 3-day.
The number of boli regurgitated per day decreased in proportion to the rumination time, from 628 boli when fed normally to 101-108 boli on 3rd day of fasting. There was no meaningful change in the cyclic rate of regurgitation during fasting.
The time spent on each bolus was remarkably reduced with the passage of the fasting day, and total time spent in remasticating per day declined, on 2nd and 3rd days of fasting, to 12 and 6 % respectively as compaired with that when sheep were fed normally.
The circadian distributions of rumination time on fasting days showed the same pattern as appeared on the day when sheep were fed normally.