Oxygen consumption and body temperature of the Chuditch (Dasyurus geoffroii)

Abstract

The average relation between O2 consumption rate and ambient temperature in the range 9–39°C for five adult litter‐mates was found to be y= 36.237–3.6821 x+ 0.26685 x2—0.0094468 x3+ 0.00011974 x4 where y is the O2 consumption rate in ml./kg min and x is the ambient temperature in °C. The O2 consumption rates of females showed a much greater variation about this regression than did the rates of males.This regression estimates the minimum O2 consumption to occur at an ambient temperature of 31.5°C but scatter diagrams show the thermal neutral range to extend from about 28 to 33°C.Twenty‐six oxygen consumption rates measured at 30°C (in the thermal neutral range) had a mean value of 67% of those predicted for eutherians of similar body weights but the range extended from 40 to 105%. Prolonged (13 to 28 hours) O2 consumption measurements at the same temperature show that, in the absence of activity, comparatively low O2 consumption rates are maintained for long periods.The linear regression equation relating simultaneous O2 consumption rates and colonic temperatures measured at an ambient temperature of 30°C estimates that O2 consumption will increase from 40 to 105% of that predicted when body temperature is raised from 34.5 to 38.7°C; and furthermore that an O2 consumption rate of 67% of the predicted should occur at a body temperature of 36.2°C.Animals kept in small cages at an ambient temperature of 30°C were found to have mean colonic temperatures of about 34.9°C during the day when they were resting and 37.4°C in the early evening when they were active. When kept at ambient temperatures lower than the thermal neutral a similar daily cycle in colonic temperature was found but the females showed a much larger variation about the daily trend than did males.The low O2 consumption rates maintained during inactivity and a lack of strict thermoregulation result in a relatively low body temperature and a considerable saving in metabolic energy is thereby effected. The higher colonic temperatures reached in the evening result mainly from the higher energy usage during acitvity.