Renal Salt and Water Excretion in the Camel (Camelus Dromedarius)

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Maloiy G.M.O
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Previous studies on the water balance (Schmidt-Nielsen, Schmidt-Nielsen, Houpt & Jarnum, 1956), urea excretion (Schmidt-Nielsen, Schmidt-Nielsen, Houpt & Jarnum, 1957a), temperature regulation (Schmidt-Nielsen, Schmidt-Nielsen, Jarnum & Houpt, 1957b), metabolism (Schmidt-Nielsen et al., 1967) water turnover (Macfarlane, Morris & Howard, 1963; Macfarlane & Howard, 1970) and renal function (Siebert & Macfarlane, 1971) of the one-humped camel have shown that its ability to withstand severe dehydration is partly due to: 1. The excretion of concentrated urine, 2. Its tolerance to dehydration (30% of initial body weight), 3. A low overall water expenditure, 4. The reduction of faecal as well as evaporative water loss. More recently Macfarlane & Siebert (1967) have examined kidney function in hydrated and dehydrated camels exposed to the sun (1000 kcalJm 2 h) in the central Australian desert (air temperatures 35-42°0). The present study was undertaken to examine further 1. The water economy, 2. The rate of urine flow and the ability of the kidney to excrete a concentrated urine, 3. The mechanism by which the camel's kidney regulates salt and water balance. 4. To estimate glomerular filtration rate and tubular reabsorption of salt and water under a variety of controlled experimental conditions. The ability of the camel to drink NaCI solutions of increasing concentrations as its only source of drinking water was also investigated. The Somali donkey, another domestic animal which is herded by nomadic pastoralists in hot semi-arid regions and occupies a similar habitat to that of the camel, was used for a comparison. A brief account of part of this work has been published (Maloiy, 1971).
East African Agricultural And Forestry Journal, 31, p. 243-259