QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online November 19, 2007
Journal of Experimental Biology 210, 4233-4243 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.009779

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JEB Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Król, E. Articles by Speakman, J. R. Search for Related Content PubMed PubMed Citation Articles by Król, E. Articles by Speakman, J. R. Social Bookmarking                         What's this?

Limits to sustained energy intake. X. Effects of fur removal on reproductive performance in laboratory mice

Elbieta Król^*, Michelle Murphy and John R. Speakman

School of Biological Sciences, University of Aberdeen, Aberdeen Centre for Energy Regulation and Obesity (ACERO), Aberdeen, AB24 2TZ, UK

^* Author for correspondence (e-mail: e.krol{at}abdn.ac.uk)

Accepted 24 September 2007

The maximum rate of sustained energy intake (SusEI) may limit reproductive effort and other aspects of animal performance. We have previously suggested that lactating mice are not limited centrally by the alimentary tract or peripherally by the mammary glands, but that the limits to SusEI are imposed by the capacity of the animal to dissipate body heat generated as a by-product of processing food and producing milk. To explore the nature of the limits to SusEI, we bred MF1 laboratory mice at 21°C and then dorsally shaved lactating females to reduce their external insulation and thereby elevate their capacity to dissipate body heat. These mice increased their food intake by 12.0% and assimilated on average 30.9 kJ day^–1 more energy than unshaved animals. With nearly identical mean litter sizes (11.4 pups for shaved and 11.3 pups for unshaved mice), shaved mothers exported 15.2% (22.0 kJ day^–1) more energy as milk than control individuals. The elevated milk production of shaved mice enabled them to wean litters that were 15.4% (12.2 g) heavier than offspring produced by unshaved mice. Our results argue against central, peripheral or extrinsic limits to SusEI at peak lactation and provide strong support for the heat dissipation limit hypothesis. More generally, we see many situations where heat dissipation may be a previously unrecognised factor constraining the evolution of endothermic animals – for example, the latitudinal and altitudinal trends in clutch and litter sizes and the migration patterns of birds.

Key words: heat dissipation limit, lactation, digestive efficiency, metabolizable energy intake, daily energy expenditure, milk production, pup energy content

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

Related articles in JEB:

LIMITS ON LACTATION

Kathryn Phillips
JEB 2007 210: iii. [Full Text]  

This article has been cited by other articles:

				S.-H. Wu, L.-N. Zhang, J. R. Speakman, and D.-H. Wang Limits to sustained energy intake. XI. A test of the heat dissipation limitation hypothesis in lactating Brandt's voles (Lasiopodomys brandtii) J. Exp. Biol., November 1, 2009; 212(21): 3455 - 3465. [Abstract] [Full Text] [PDF]

				Z.-J. Zhao and J. Cao Effect of fur removal on the thermal conductance and energy budget in lactating Swiss mice J. Exp. Biol., August 15, 2009; 212(16): 2541 - 2549. [Abstract] [Full Text] [PDF]

				C. U Guillemette, Q. E Fletcher, S. Boutin, R. M Hodges, A. G McAdam, and M. M Humphries Lactating red squirrels experiencing high heat load occupy less insulated nests Biol Lett, April 23, 2009; 5(2): 166 - 168. [Abstract] [Full Text] [PDF]