ABSTRACT
A comparative study of heat production and dissipation was carried out on Rhabdomys pumilio from two extremely different climatic zones. Our results show higher oxygen consumption (Vo2) values for the desert population at Ta = 5 degrees C when compared to the mesic population. The overall thermal conductance is also higher for the desert population. It seems as though penetration into mesic areas of R. pumilio, which originated in an arid zone, was accompanied by an increase in body mass.
Subject(s)
Acclimatization , Body Temperature Regulation , Muridae/physiology , Animals , Climate , Female , Geography , Male , Oxygen ConsumptionABSTRACT
1. A comparative study of calcium and bicarbonate in the urine was carried out on the subterranean mole rat Cryptomys hottenttus and the terrestrial vlei rat Otomys irroratus. 2. The two species were kept on two different diets; carrots, a high calcium diet (41 mg/ 100 kg) or potatoes, a low calcium diet (14 mg/ 100g). 3. The results show that the urine of the mole rat contained high values of calcium bicarbonate on either diet. 4. The urine of the vlei rat showed high values of calcium bicarbonate only when kept on the high calcium diet. 5. From these results we assume that in subterranean rodents excretion of calcium bicarbonate is an adaptive mechanism to unload CO2 without increasing its concentration in the hypercapnic environment.
Subject(s)
Bicarbonates/urine , Mole Rats/urine , Muridae/urine , Adaptation, Physiological , Animals , Calcium, Dietary/metabolism , Diet , Mole Rats/physiology , Muridae/physiologyABSTRACT
Resting metabolic rates (RMR) below thermoneutrality in adult hyrax acclimated to 26, 15 and 10 degrees C remained unchanged, i.e. thermal conductance (K) remained constant. Conductance in juveniles decreased with acclimation to lower ambient temperatures (Ta). Body temperature (Tb) dropped by 3.8 degrees C in adults exposed to Ta of 30-5 degrees C. The decrease was constant. Body temperature fell by 1.5 degrees C in juveniles exposed to Ta of 30-20 degrees C but stabilized between 20 and 5 degrees C. The labile Tb, associated with behavioural strategies and lower than predicted RMR, can be seen as an energy-conserving mechanism of particular importance during winter conditions.
Subject(s)
Body Temperature , Energy Metabolism , Hyraxes/growth & development , Mammals/growth & development , Acclimatization , Aging , Animals , Body Temperature Regulation , Circadian Rhythm , Female , Male , TemperatureABSTRACT
In rams a positive correlation (P less than 0.001) existed between average testosterone levels from 30-min blood sampling for 18 h and average testosterone levels of samples taken 0, 1 and 2 h after injection of LH-RH administered 90 min after anaesthesia. Attempts were therefore made to assess testosterone status by LH-RH challenge and limited blood sampling in animals immobilized in their natural habitat. In impala (Aepyceros melampus) territorial males had higher plasma testosterone values than did bachelors after LH-RH challenge (8.1 compared with 2.6 ng/ml, P less than 0.05). In blesbok (Damaliscus dorcas), the relationship was less clear, but testicular volume was correlated with plasma testosterone concentration and with testicular responsiveness measured by testosterone produced per unit of LH (P less than 0.001 and P less than 0.05, respectively). The LH-RH challenge technique therefore has value as a measure of testicular function and permits study of ungulates in their natural environment.
Subject(s)
Animal Population Groups/physiology , Animals, Wild/physiology , Antelopes/physiology , Artiodactyla/physiology , Gonadotropin-Releasing Hormone , Reproduction , Social Environment , Testis/physiology , Testosterone/blood , Animals , Luteinizing Hormone/blood , Male , SheepABSTRACT
Rock hyraces were exposed to the dorsal gland and urinary odors' of conspecifics in a test chamber constructed such that electrocardiographic biopotential could be picked up through the plantar surfaces of the feet. Both heart rate acceleration and deceleration were observed. Female hyraces responded more strongly to odors than males, but no reponse was observed towards the odor of the dorsal gland of sexually inactive males. Electrocardiography allows a more sensitive measurement of response to odor stimuli than has hitherto been reported, and the technique may have a wide applicability in studies on other mammalian species with naked foot soles.
