Oxygen consumption and heat production in chinchillas

Abstract

[With 2 Tables and 1 Fig.]The oxygen consumption of chinchillas (average body weight=402.5 g) was studied in a closed-circuit system respirometer in ambient temperatures from 5 to 35°C. The thermoneutral zone of these rodents is between 20 and 30°C where the minimal resting metabolism rate averages 0.6812 ccm 0 2 /g/h. With the decrease of ambient temperature from 30 to 5°C the oxygen consumption increases by 85%>. Both the metabolism rate and the heat production are lower in the chinchilla than in other rodent species with similar body weight.The chinchillas (Chinchilla lanigcra Molina, 1782) have been thoroughly studied because of their great importance in fur industry. Recently they are often used in comparative physiological studies (White, 1964) but there are almost no data on the metabolism rate of chinchilla. Therefore it seemed appropriate to study the oxygen consumption and the chemical thermoregulation in this interesting rodent. MATERIAL AND METHODSMale chinchillas (Chinchilla lanigcra Molina, 1782) were used for the experiments. These animals were raised at a farm in the temperature of 15°C (± 5°C) and in natural illumination.The chemical thermoregulation was determined by the oxygen consumption in a modified Kalabukhov-Skvartzov respirometer (Grodzinski, 1961). In this apparatus the resting metabolism rate (RMR) was measured. The animals were not fasted before runs. For measurements the animals were placed in 9 liter chambers slightly limiting their movements. The oxygen consumption was determined in six ambient temperatures, every 5° from +5 to +35 c C. The total of 63 thirty minute runs was done on six individuals. The rectal temperature was measured before and after each run with a tele-thermistor thermometer. All experiments were done during the winter. The mean body weight of animals used was 402.5 g (from 330.0 to 498.0 g).The oxygen consumption was measured in ccm/g/h. From this the following values were computed: heat production in cal/g/h, intensity of chemical thermoregulation in per cent and the body insulation index from the formula of Hart. & Heroux (1955).[81]