Energy costs of locomotion in wapiti

Abstract

Increment in EE (energy expenditure above standing) due to walking increased linearly with velocity (in km/hr). EEwalk is in kcal/kg hr #1: EEwalk = 0.4165 V + 0.0148 (r2 = 0.73, n=40) #2: EEwalk = 0.3426 V + 0.5697 (r2 = 0.62, n=44) pooled: EEwalk = 0.3714 V + 0.3248 (r2 = 0.53, n=84) Table 1: EE for standing, lying, and the 3 speeds of walking. 2 animals were signif. different Table 2: EE per km at different velocities (constant for one animal, decreases with speed for the other). Both animals had same stride frequency at a given speed: Velocity = 0.064 * Str. Freq. - 1.901 r2=0.95, n=59 Taylor et al. 1974 equation predicts a slope of EE increase with speed to be 0.339 kcal/kg km for an animal of this weight. Here results were 0.37, only slightly greater. In contrast to EE expressed as a function of time, total EE per unit distance usually declines with increasing speed to a min. cost which as been widely used in cross-species comparisons. This is due largely to the changing proportional contributions of standard metabolism and the activity increment as velocity increases. Assuming a constant cost for 1 stride (Gold 1973) = 0.0003 kcal/kg, predicted EE compared closely with measured values (p. 369). Assuming 1.7 hr is spent travelling (refs) and assuming an average 3 km/hr, walking would represent an 8.7% increase in daily EE. Would be much more if including cost of walking during feeding.