The grazing behaviour and heart rate of Japanese Black cows were studied on tame pasture with high amount of herbage and native pasture with very sparse herbage. On both pastures, 24hr observations of grazing habits were conducted and heart rates were also measured at 5 min intervals for 24hr by telemetry with two cows in a herd.
The time spent in grazing were prolonged on the native pasture(693min) and grazing time was markedly longer on the native pasture than on the tame pasture (423min). However, longer time was spent in ruminating on the tame pasture (452min) compared with on the native pasture(334min). From these results, it is suggested that intake of herbage was less on the native pasture than on the tame pasture. The amount of loafing time and the total distance of walking were not different between pastures.
Heart rates measured at same activities were lower on the native pasture than on the tame pasture and mean of heart rates was 14-16% lower on the native pasture than on the tame pasture.
It was considered that the lower heart rates would be caused by the smaller amount of ingested herbage on the native pasture.