Seasonal variation in the plasma and the urine electrolyte concentration of the arid zone kangaroos Megaleia rufa and the Macropus robustus

Abstract

The seasonal variation in the plasma and urine electrolyte concentration and osmolality of the arid zone kangaroos Megaleia rufa (red kangaroo) and Macropus robustus (euro) has been examined. The urine osmolality of both species appeared to be influenced by environmental temperatures and also the status of feed. The osmolality of urine from red kangaroos was generally higher than that from euros. However, the relative medullary thickness of euro kidneys was greater than that of red kangaroo kidneys, indicating that euros may have the greater urine-concentrating capability. The pattern of sodium and potassium excretion indicated that species of Atriplex (saltbush) and Kochia (bluebush), which are high in sodium relative to potassium, may comprise a major part of the diet of the red kangaroo and euro in western New South Wales.