SUMMARYBody mass is the primary determinant of an animalʼs energy requirements. At their optimum walking speed, large animals have lower mass-specific energy requirements for locomotion than small ones. In animals ranging in size from 0.8g (roach) to 260kg (zebu steer), the minimum cost of transport (COT min ) decreases with increasing body size roughly as COT min ϰbody mass (M b ) -0.316±0.023 (95% CI). Typically, the variation of COT min with body mass is weaker at the intraspecific level as a result of physiological and geometric similarity within closely related species. The interspecific relationship estimates that an adult elephant, with twice the body mass of a mid-sized elephant, should be able to move its body approximately 23% cheaper than the smaller elephant. We sought to determine whether adult Asian and sub-adult African elephants follow a single quasi-intraspecific relationship, and extend the interspecific relationship between COT min and body mass to 12-fold larger animals. Physiological and possibly geometric similarity between adult Asian elephants and sub-adult African elephants caused body mass to have a no effect on COT min (COT min ϰM b 0.007±0.455). The COT min in elephants occurred at walking speeds between 1.3 and ~1.5ms . The quasi-intraspecific relationship between body mass and COT min among elephants caused the interspecific relationship to underestimate COT min in larger elephants.

This study sought to quantify the rate of energy expenditure ( _ VO 2 ), the total cost of transport (COT tot ) and the net cost of transport (COT net ) in camels Camelus dromedaries and donkeys Equus asinus during level locomotion. _ VO 2 of camels and domestic donkeys were measured at exercise speeds between 0 and 4.17 m s À1 . Resting _ VO 2 for camels was significantly (Po0.05) lower than predicted, while donkeys exhibited resting values similar to mammals of the same body mass. In both camels and donkeys _ VO 2 increased in a nearly linear fashion over the range of exercise speeds. The minimum COT tot 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 COT tot while walking and trotting. In both camels and donkeys, the minimum COT tot was significantly (Po0.05) lower than the predicted COT tot for mammals of the same body mass. The COT net in both camels and donkeys was determined to be gait dependent and significantly (Po0.05) lower than the predicted minimum COT net values for walking and running. The low COT seen in camels and donkeys results in energy and water savings. IntoductionThe one-humped camel Camelus dromedarius and domesticated donkey Equus asinus are large desert-adapted ungulates of great economic importance to nomadic inhabitants of hot arid regions in Africa and the Middle East. While camels have proven to be remarkably suited for transporting loads long distances, slow-footed donkeys have demonstrated an outstanding capacity to carry loads in mountainous terrain. For desert-adapted species, selective pressures should favour locomotory adaptations that lower energy expenditure and reduce water loss. Therefore, we thought it would be of interest to determine the effect that locomotion has on energy expenditure ( _ VO 2 ) in exercising camels and donkeys.Working camels and donkeys are often required to move at a range of slow to moderate speeds not of their choosing. However, when migrating, wild African ungulates choose to move at a narrow range of speeds near the mid-range within each gait (Pennycuick, 1975). At this preferred range of speeds, the energetic cost of transport (COT), the energy (J) required to move a unit of body mass (kg) a given distance (m), is minimized in some species (Hoyt & Taylor, 1981;Alexander, 1989;Langman et al., 1995;Griffin et al., 2004). The COT can be calculated as the total cost of transport (COT tot ) or the net cost of transport (COT net ) depending on the level of analyses. The COT tot reports how much total energy is expended for locomotion, while the COT net provides an estimate of the energy required by active muscles during locomotion above that required for standing quietly. We sought to determine whether economy in energy expenditure and muscle performance existed in large desert-adapted ungulates while exercising at a wide range of speeds.

SUMMARYGigantic size presents both opportunities and challenges in thermoregulation. Allometric scaling relationships suggest that gigantic animals have difficulty dissipating metabolic heat. Large body size permits the maintenance of fairly constant core body temperatures in ectothermic animals by means of gigantothermy. Conversely, gigantothermy combined with endothermic metabolic rate and activity likely results in heat production rates that exceed heat loss rates. In tropical environments, it has been suggested that a substantial rate of heat storage might result in a potentially lethal rise in core body temperature in both elephants and endothermic dinosaurs. However, the behavioral choice of nocturnal activity might reduce heat storage. We sought to test the hypothesis that there is a functionally significant relationship between heat storage and locomotion in Asian elephants (Elephas maximus), and model the thermoregulatory constraints on activity in elephants and a similarly sized migratory dinosaur, Edmontosaurus. Pre-and post-exercise (N=37 trials) measurements of core body temperature and skin temperature, using thermography were made in two adult female Asian elephants at the Audubon Zoo in New Orleans, LA, USA. Over ambient air temperatures ranging from 8 to 34.5°C, when elephants exercised in full sun, ~56 to 100% of active metabolic heat production was stored in core body tissues. We estimate that during nocturnal activity, in the absence of solar radiation, between 5 and 64% of metabolic heat production would be stored in core tissues. Potentially lethal rates of heat storage in active elephants and Edmontosaurus could be behaviorally regulated by nocturnal activity.

The objectives of this study were twofold: first, to develop noninvasive techniques for measuring the thermal characteristics of materials commonly used in construction of zoological exhibits; and second, to use these techniques to compare a portion of the Audubon Zoo's sea lion exhibit before and after renovations completed in 1993. We characterized the thermal environment of the sea lion enclosures by diurnal measurements of the two primary heat gain components, longwave and shortwave radiation. Measurements of wet sea lion coats showed that they absorbed 91.6% of all types of shortwave radiation. The surface of gunite “rocks” in the enclosure in 1991 reflected 41% of shortwave radiation, while the same area, after renovation, reflected only 8% of shortwave radiation. Darkening the color of the gunite surfaces and adding two effective shaded areas to the enclosure decreased the shortwave heat load in the exposed beach areas and the longwave heat load in the shaded areas. We conclude that thermal properties of materials used in zoo enclosures are an important determinant of the animals' heat load and should be considered in the design of captive habitats. © 1996 Wiley‐Liss, Inc.

The purpose of this study was to quantify the thermal microclimate provided by a shade structure in the African elephant enclosure at Zoo Atlanta. The hypothesis was that the interior of a weather instrument shelter (a Stevenson screen) would provide the maximum environmental shielding and the coolest possible ambient conditions without artificial heating or cooling. The ambient conditions inside the Stevenson screen were compared with the ambient conditions in the shaded and nonshaded sections of the exhibit to quantify the extremes possible under the environmental conditions. The Stevenson screen reduced the radiant heat load by 766 W m -2. The shade structure in the elephant enclosure reduced the radiant heat load by 278 W m -2 , which was 37% of the total possible reduction represented by the interior of the Stevenson screen. The longwave radiant heat was 10% greater in the direct sun and 37% greater in the shaded area than the shortwave radiant heat. The shade structure reduced the shortwave radiant heat by 254 W m -2 or 43%, but only reduced the longwave radiant heat by 24 W m -2 or 3%. Shade structures alone may not provide adequate protection from radiant heat for captive species. A cool microclimate in an artificial enclosure should be designed to reduce all sources of radiant heat.

Measurements of rate of oxygen consumption (VO2) recorded during controlled exercise is used to assess cardiovascular health in test individuals. In low- or middle-income countries, where Mycobacterium tuberculosis is common and older VO2 systems are in use, three specific preventative measures should be in place to prevent the transmission of tuberculosis. These include: (1) disinfecting reusable plastic masks and rubber tubing with bleach solution; (2) limiting maximum exposure of test individuals to Cl2 gas to <1–3 ppm for a duration of ≤15 min to prevent respiratory distress; and (3) carefully inspecting for degradation of plastic VO2 masks and rubber tubing repeatedly disinfected with bleach and replace these at the first signs of deterioration.

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