In order to clarify the seasonal changes of grazing behaviors in Japanese Black Breed cows, we observed three cows ( 6-10 years old) constantly for 24 hours on Sambe native grassland in Shimane Prefecture from May to October.
The results obtained are summarized as follows :
1. The grazing time per head during 24 hours varied from 336 to 610 minutes. The maximum grazing time was observed in September while the minimum one was observed in August. In May, June, and July, grazing hours were concentrated in the daytime, while they were dispersed through the whole day in August, September, and October. The grazing time at night was increased remarkably in August.
2. The ruminating time per head during 24 hours varied from 382 to 475 minutes. The maximum ruminating time was observed in August while the miniinum one was observed in May. The ratio of ruminating time to grazing time (R/G) was the highest in August (1.41) and the lowest in October (0.66).
3. The resting time per head during 24 hours varied from 332 to 453 minutes. The maximum resting time was observed in August while the minimum one was observed in October. The resting time at night was longer than that in daytime in every month except August.
4. The total time spent in migrating and loafing per head during 24 hours varied from 67 to 179 minutes. The maximum time was observed in July while the minimum one was observed in September.
5. Both the frequencies of defecation and urination were the greatest in June and that of drinking was the greatest in August.
6. The walked distance per head during 24 hours varied from 3.8 to 9.4 kilometers. The longest distance was observed in August while the shortest one was observed in October.
7. The topographical distribution of every behavior shows that the cows spent the most time in open slope and the shortest time in the pond in every month except August. In August, the cows spent the most time in the pond which is located next to an open slope.