In this investigation energy demands from offspring were varied for the MF1 mouse after litter sizes were manipulated and set to 5 pups/litter or 16 pups/litter by cross-fostering to examine the effects on immediate lactation and subsequent reproductive performance. Pups reared in manipulated large litters grew slower and were weaned lighter (half the size of pups reared in small litters) than pups reared in manipulated small litters. Mortality of pups was high in the large litters but pups did not die in small litters. The results of a subsequent reproduction that followed the first lactation suggested an apparent cost for the female group that previously reared pups in large litters. This is because in the subsequent reproduction, the group raised litters that were significantly (P<0.05) 12.7g less in mass than litters raised by females that previously reared pups in small litters. This apparent cost, however, did not appear to have severe negative impact on the general reproductive performance because data showed comparable litter sizes and masses at birth, growth rates of pups, and the number and masses of pups weaned between this group and females that previously reared pups in small litters. At reproductive age, female offspring previously weaned from large litters weighted significantly (P<0.05) 5.8g less than female offspring previously weaned from small litters. During their first breeding attempt or episode, female offspring previously weaned from large litters did not catch-up in body mass with those previously weaned from small litters. In spite of this, the two groups ingested similar quantities of food prior to mating and during lactation. The groups did not differ significantly (P>0.05) in efficiencies of energy utilization, milk energy output and daily energy expenditure. Consequently, they showed comparable breeding success. Different age groups of male and female offspring previously weaned from manipulated small (5 pups/litter) or large litters (16 pups/litter) and unmanipulated normal litters (10 pups/litter) varied significantly in body mass and did not show compensatory growth at the time they were examined for susceptibility to obesity and glucose intolerance. A batch of six months old male offspring previously weaned from litters whose mothers were fed a particular macronutrient diet during lactation did not differ significantly in body mass when they were also examined for susceptibility to obesity. All groups and sexes showed a tendency to develop obesity when they were challenged with a diet that contained up to 45% fat by calories. Development of obesity did not appear to depend on a particular litter size in which the mice were previously reared and weaned or whether the mice were previously suckled by mothers that were fed a particular macronutrient diet. However, the development of obesity exhibited sexual dimorphism with the male offspring showing a higher tendency to develop obesity than female offspring.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:499669 |
| Date | January 2009 |
| Creators | Agyeman, Duah Osei |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=26022 |
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