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Animal Sciences

University of Nebraska - Lincoln

2006

Selection

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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 Jan 2006

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

Department of Animal Science: Faculty Publications

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. …


Correlated Responses In Maternal Performance Following Divergent Selection For Heat Loss In Mice, J. M. Mcdonald, Merlyn . K. Nielsen Jan 2006

Correlated Responses In Maternal Performance Following Divergent Selection For Heat Loss In Mice, J. M. Mcdonald, Merlyn . K. Nielsen

Department of Animal Science: Faculty Publications

Divergent selection in mice was applied in 3 independent replicates for high (maintenance high; MH) and low (maintenance low; ML) heat loss for 16 generations. An unselected control (maintenance control; MC) was also maintained in all replicates. Selection ceased for 26 generations; heat-loss measurement and selection resumed at generation 42. Lactation performance, dam weight, dam feed intake, and efficiency of production of pup weight were recorded or calculated for MH and ML dams in all 3 replicates at generation 46 or 47 with the objective of determining whether selection for heat loss has created correlated responses in maternal performance. One-half …