• camels;
  • donkeys;
  • energy expenditure;
  • cost of transport


This study sought to quantify the rate of energy expenditure (inline image), the total cost of transport (COTtot) and the net cost of transport (COTnet) in camels Camelus dromedaries and donkeys Equus asinus during level locomotion. inline image of camels and domestic donkeys were measured at exercise speeds between 0 and 4.17 m s−1. Resting inline image for camels was significantly (P<0.05) lower than predicted, while donkeys exhibited resting values similar to mammals of the same body mass. In both camels and donkeys inline image increased in a nearly linear fashion over the range of exercise speeds. The minimum COTtot of camels in the walking and pacing gaits were not significantly different (P=0.27). Similarly, donkeys exhibited no significant difference (P=0.09) in the minimum COTtot while walking and trotting. In both camels and donkeys, the minimum COTtot was significantly (P<0.05) lower than the predicted COTtot for mammals of the same body mass. The COTnet in both camels and donkeys was determined to be gait dependent and significantly (P<0.05) lower than the predicted minimum COTnet values for walking and running. The low COT seen in camels and donkeys results in energy and water savings.