Graphs of physiological variables measured or calculated in healthy, boma-habituated, sub-adult, male white rhinoceros (n = 6), assigned to two treatments administered once each in random order: ES (light blue circles) and EB (dark blue circles). Data were collected 30, 40 and 50 min after the rhinoceros became recumbent (t30, t40 and t50, respectively); either 0.9% saline (treatment ES) or butorphanol (treatment EB) was injected IV at t37. Refer to Fig. 1 legend for further details.

VO₂, oxygen consumption; T_PA, pulmonary artery temperature; T_R, rectal temperature; OER, oxygen extraction ratio; VCO₂, carbon dioxide production.