We measured daily energy expenditure (DEE) and water turnover rates in lactating and non-lactating short beaked echidnas (Tachyglossus aculeatus) using the doubly labelled water technique during the lactation period in spring. Reproductively inactive echidnas were on average significantly heavier (median: 3354 g; range: 2929-3780 g; N=4) than lactating females (median: 2695 g; range: 2690-2715 g; N=3) during the equivalent time period. The median water flux rate of lactating echidnas (152 ml day-1; range: 120-198 ml day -1) did not differ significantly from that of non-lactating females (170 ml day-1; range: 128-227 ml day-1). The median DEE of echidnas that were lactating was 645 kJ day-1 (range: 581-850 kJ day-1), which was not different from the median DEE of non-reproductive control females (763 kJ day-1; range: 720-766 kJ day-1). Lactating females somehow compensate for the energy costs of milk production, resulting in a daily energy budget that is not different from that of non-reproductive females. At least part of their energy minimising strategy could involve the use of moderate heterothermy, allowing a greater proportion of daily energy expenditure to diverted to milk production. © 2003 Elsevier Inc. All rights reserved.

Item Type:	Refereed Article
Research Division:	Biological Sciences
Research Group:	Other biological sciences
Research Field:	Other biological sciences not elsewhere classified
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the environmental sciences
UTAS Author:	Andersen, NA (Dr Niels Andersen)
UTAS Author:	Nicol, SC (Associate Professor Stewart Nicol)
ID Code:	28363
Year Published:	2003
Web of Science® Times Cited:	18
Deposited By:	Anatomy and Physiology
Deposited On:	2003-08-01
Last Modified:	2004-03-23
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