In order to study the effect of age and nurrsing on the grazing behaviors, four groups of Japanese Black Breed of Cattle, 3 heifers (18-21 monthes after birth), 3 prime cows (5-7 years old), 3 prime cows nursing (5-6 years old) and 3 old cows (9-10 years old) were used in this study under constant observation on range for 24 hours in May 23 to 30, 1961.
The results obtained are summarized as follows :
1. Grazing times per 24 hours of old and nursing groups were longer than those of young and prime ones.
2. On ruminating and grazing times per 24 hours, a similar tendency was found in old and nursing groups, but the ruminating times of these groups were short in spite of the fact that the grazing times were long.
The ratio of ruminating time to grazing time was low than expected in both groups.
3. The remasticating time was longer in old group than in young, and the number of remastication was few in old group.
4. It seems that the effect of nursing on the resting time was most remarkable and the resting time of nursing group was the longest of all groups.
5. The migrating time of nursing group was the longest and its loafing time was the longest of all.
6. The distance walked was the longest in the nursing group, and the shortest in the old.