Comparison of feed energy costs of maintenance, lean deposition, and fat deposition in three lines of mice selected for heat loss

D. L. Eggert, Merlyn K Nielsen

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Three replications of mouse selection populations for high heat loss (MH), low heat loss (ML), and a nonselected control (MC) were used to estimate the feed energy costs of maintenance and gain and to test whether selection had changed these costs. At 21 and 49 d of age, mice were weighed and subjected to dual x-ray densitometry measurement for prediction of body composition. At 21 d, mice were randomly assigned to an ad libitum, an 80% of ad libitum, or a 60% of ad libitum feeding group for 28-d collection of individual feed intake. Data were analyzed using 3 approaches. The first approach was an attempt to partition energy intake between costs for maintenance, fat deposition, and lean deposition for each replicate, sex, and line by multiple regression of feed intake on the sum of daily metabolic weight (kg0.75), fat gain, and lean gain. Approach II was a less restrictive attempt to partition energy intake between costs for maintenance and total gain for each replicate, sex, and line by multiple regression of feed intake on the sum of daily metabolic weight and total gain. Approach III used multiple regression on the entire data set with pooled regressions on fat and lean gains, and subclass regressions for maintenance. Contrasts were conducted to test the effect of selection (MH - ML) and asymmetry of selection [(MH + ML)/2 - MC] for the various energy costs. In approach I, there were no differences between lines for costs of maintenance, fat deposition, or protein deposition, but we question our ability to estimate these accurately. In approach II, selection changed both cost of maintenance (P = 0.03) and gain (P = 0.05); MH mice had greater per unit costs than ML mice for both. Asymmetry of the selection response was found in approach II for the cost of maintenance (P = 0.06). In approach III, the effect of selection (P < 0.01) contributed to differences in the maintenance cost, but asymmetry of selection (P > 0.17) was not evident. Sex effects were found for the cost of fat deposition (P = 0.02) in approach I and the cost of gain (P = 0.001) in approach II; females had a greater cost per unit than males. When costs per unit of fat and per unit of lean gain were assumed to be the same for both sexes (approach III), females had a somewhat greater estimate for maintenance cost (P = 0.10). We conclude that selection for heat loss has changed the costs for maintenance per unit size but probably not the costs for gain.

Original languageEnglish (US)
Pages (from-to)276-282
Number of pages7
JournalJournal of animal science
Volume84
Issue number2
StatePublished - Feb 1 2006

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energy costs
Hot Temperature
Fats
Maintenance
heat
Costs and Cost Analysis
mice
lipids
feed intake
gender
energy intake
protein deposition
ad libitum feeding
selection response
densitometry
body composition
X-radiation
Energy Intake
testing
prediction

Keywords

  • Fat deposition energy
  • Lean deposition energy
  • Maintenance energy
  • Mice
  • Selection

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics

Cite this

Comparison of feed energy costs of maintenance, lean deposition, and fat deposition in three lines of mice selected for heat loss. / Eggert, D. L.; Nielsen, Merlyn K.

In: Journal of animal science, Vol. 84, No. 2, 01.02.2006, p. 276-282.

Research output: Contribution to journalArticle

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