Limits to sustained energy intake. XVIII. Energy intake and reproductive output during lactation in Swiss mice raising small litters

Zhi-Jun Zhao*, De-Guang Song, Zhen-Cheng Su, Wen-Bo Wei, Xian-Bin Liu, John R. Speakman

*Corresponding author for this work

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Limits to sustained energy intake (SusEI) during lactation in Swiss mice have been suggested to reflect the secretory capacity of the mammary glands. However, an alternative explanation is that milk production and food intake are regulated to match the limited growth capacity of the offspring. In the present study, female Swiss mice were experimentally manipulated in two ways litter sizes were adjusted to be between 1 and 9 pups and mice were exposed to either warm (21 degrees C) or cold (5 degrees C) conditions from day 10 of lactation. Energy intake, number of pups and litter mass, milk energy output (MEO), thermogenesis, mass of the mammary glands and brown adipose tissue cytochrome c oxidase activity of the mothers were measured. At 21 and 5 C, pup mass at weaning was almost independent of litter size. Positive correlations were observed between the number of pups, litter mass, asymptotic food intake and MEO. These data were consistent with the suggestion that in small litters, pup requirements may be the major factor limiting milk production. Pups raised at 5 C had significantly lower body masses than those raised at 21 C. This was despite the fact that milk production and energy intake at the same litter sizes were both substantially higher in females raising pups at 5 C. This suggests that pup growth capacity is lower in the cold, perhaps due to pups allocating ingested energy to fuel thermogenesis. Differences in observed levels of milk production under different conditions may then reflect a complex interplay between factors limiting maternal performance (peripheral limitation and heat dissipation: generally better when it is cooler) and factors influencing maximum pup growth (litter size and temperature: generally better when it is hotter), and may together result in an optimal temperature favouring reproduction.

Original languageEnglish
Pages (from-to)2349-2358
Number of pages10
JournalJournal of Experimental Biology
Volume216
Issue number12
DOIs
Publication statusPublished - Jun 2013

Keywords

  • temperature
  • heat dissipation limit
  • reproductive performance
  • milk energy output
  • peripheral limit
  • pup growth
  • thermogenesis
  • voles lasiopodomys-brandtii
  • dissipation limitation hypothesis
  • brown fat mitochondria
  • mus musculus
  • food-intake
  • peromyscus-maniculatus
  • laboratory mice
  • metabolic-rate
  • small mammals
  • serum leptin

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