Rumination activity was measured in three sheep intravenously infused with adrenalin. In the first Expt, adrenalin was administered for 4 hr., that is, 9:00-13:00 or 13:00-17:00, in dose of 10μg/hr･kg body-weight. In the second Expt, adrenalin were infused during every 2 hr. of 13:00-15 00, 21:00-23:00 and 3:00-5:00, at a dose of either 20 or 10μg/hr･kg body-weight. Adrenalin infusion was made with an peristaltic pump at 50ml of fluid volume per hour through the jugular vein catheter. In both experiments, the ainmals were offered the hay diets of 1% body weight as dry matter, at 9:00 and 17:00. The ruminating behaviour was recorded by using the strain gauge held under the jaw of sheep, for two days and three days in the 1st and 2nd Expts, respectively.
Adrenalin infusion shortend the daily ruminating time in the 1st Expt, and tended to reduce the daily ruminating time but the tendency was not significant in the 2nd Expt. The daily mean of parameters in rumination activities, such as number of boli, number of rumination periods and cyclic rate of regurgitation, were not so much affected by adrenalin infusion, in both experimets. The ruminating time markedly diminished during both periods of adrenalin infusion in the 1st Expt, but the ruminating time declined in the 2nd Expt, only for 13:00-15:00, the first period of adrenalin infusion in a day.