裏山放牧哺乳子牛の行動およびエネルギー消費率について

The grazing behaviours and rates of energy expenditure were studied with 5 suckling calves of the Japanese Black Breed. Furthermore the difference was compared between the behavioural pattern when confined in the free-barn and when grazed on the moun tain range neighbouring the farm-house.
The principal results obtained were as follows :
1. The grazing and loafing hours were longer, and the suckling and ruminating hours were shorter, on the range than in the free-barn. But there was no difference in the time spent for resting.
2. As compared to the abult cattle, the time spent for grazing and ruminating during 24 hours by the calves was half, and the time spent for resting and loafing was about two times as much. This result suggested that one reason for the decrease in body weight of the grazing calves was their unproductive behaviour.
3. As the season changed from spring to autumn, the calves spent more hours for grazing and ruminating, and less hours for resting and loafing.
4. The grazing hours increased markedly when the calves grew to two months old, but thereafter no increase was found. The resting hours reduced gradually as the age advanced. The rgazing and ruminating hours of the grazing calves were considerably shorter than those of the adult cows or young steers.
5. The 24-hour grazing pattern in particular showed that grazing hours were remarkably shorter and ruminating hours were longer at night than in daytime.
6. The heart rate increased by only 5% when grazed on the range. It seemed that the energy expenditure did not increase much by grazing when the calf had been kept in the free-barn before grazing.
7. From these results, it was concluded that the calf-grazing on the range neighbouring the farm-house was profitable when the calves were creep-fed.