Metabolism and evaporative heat loss in the dik-dik antelope (Rhynchotragus kirki)

Abstract

1. Under controlled conditions, the rate of oxygen consumption (View the MathML source) respiratory frequency, evaporative water loss, heat balance, rectal (Trec) and surface temperatures were determined in the dik-dik antelopes at ambient temperatures (Ta) ranging from 1 to 44°C. 2. The thermal neutral zone was found to be between 24 and 35°C. 3. Respiratory frequency ranged between 27 and 630 breaths/min. 4. At a Ta of 44°C, 95% of the heat produced by the dik-dik was lost via respiratory evaporation. Despite an increase in Trec, cutaneous evaporation did not increase. 5. During panting, View the MathML source increased in accordance with the expected Q10 effect, contrary to earlier findings. 6. Measurements of circadian rhythm [LD 12:12 (7–19) CT26°C] in View the MathML source showed that the minimum .VO2 (0.42ml O2/g/hr) occurred at midnight while the maximum (0.78ml O2/g/hr) occurred at midday. The 24 hr mean View the MathML source was 0.61 ml O2/g/hr. 7. These measurements suggest that in nature, determinants other than light may be responsible for triggering the variations observed in View the MathML source