Figure 2.

Energy expenditures for feeding at different heights for 5 min compared with the net energy costs for travelling different distances. The additional metabolic rate owing to an increased blood pressure is related to a resting posture of the neck with an inclination angle of 40° between the neck and the horizontal plane. Yellow line, raising the neck from the resting position; red line, keeping the neck for 5 min in position; green line, energy cost of transport: walking distance 10 m; blue line, energy cost of transport: walking distance 20 m; dark blue line, energy cost of transport: walking distance 30 m.