Microdialysis in free-moving reindeer
1.Purpose
The purpose of this proposal is to develop new 3Rs approaches to investigating the relationship between hormone secretion, metabolism and the temporal organization of physiology and behavior in ruminants. Like humans, ruminants organize their days into periods of activity and rest, but rather than a simple day / night patterning, activity bouts of a few hours duration occur all around the clock, separated by rest periods of a few hours. This patterning is known as ultradian rhythmicity and is generally believed to reflect the demands of ruminant nutrition: to keep the rumen functioning efficiently as a food supplying fermenting vat, it must be continuously re-supplied by grazing. How rumen fermentation is coordinated with metabolic energy demands and behaviour is an important unresolved issue, with major implications for farm animal health. In this proposal we wish to develop novel 3Rs research approaches allowing a quantitative analysis of the links between two key hormones controlling temporal organization (melatonin and cortisol), production of rumen metabolites (volatile fatty acids – the energy nutrient provided by rumen fermentation) and ruminant behaviour. The key innovation is to develop methodology allowing us to use a portable microdialysis device (U-rhythm), originally designed for medical diagnostics to assay hormone and rumen metabolite levels in freely moving reindeer. To get a comprehensive picture within individual animals, we will marry this novel technology with accepted approaches to assaying activity (actiwatch accelerometers in a collar), and metabolism (subcutaneous body temperature easured using an Anipill datalogger).
2.Distress
Fitting of the U-Rhythm microdialyis device requires subcutaneous insertion of a cannula needle, while implantation of an Anipill data logger requires a small skin incision to be made. These procedures rate as moderate distress, and can be performed under local anesthesia only, in the highly tamed animals. Blood sampling from the jugular vein will cause mild distress.
3.Expected benefit
Mouse / human templates for circadian-dominated behavioural organization are not readily applicable to ruminants, and the planned studies will provide new insights into the roles of rumen metabolites and ultradian hormone (especially cortisol) secretion in organization of activity. The results will have wide relevance in veterinarian and live-stock research directed at improving health, welfare and performance.
4.Animals
Reindeer
5.3Rs
Reduction: This study will develop an approach to be used in small numbers of tame animals, where serial sampling allows individual animals to yield rich information.
Refinement: The approach will use small numbers of tame animals used to human contact from an early age, combined with biologging methods (U-Rhythm, Anipill) in which data can be collected from freely moving animals in controlled semi natural settings. This approach reduces confounding effects of stress, improving data quality.
Replacement: Krogh's principle states: "for such a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied." Norwegian reindeer are ideally suited to study how endocrine and metabolic signals organize behavior because dependent on time of year, there are distinctive periods when behaviour is dominantly ultradian and other periods where diel / circadian patterning dominates.
The purpose of this proposal is to develop new 3Rs approaches to investigating the relationship between hormone secretion, metabolism and the temporal organization of physiology and behavior in ruminants. Like humans, ruminants organize their days into periods of activity and rest, but rather than a simple day / night patterning, activity bouts of a few hours duration occur all around the clock, separated by rest periods of a few hours. This patterning is known as ultradian rhythmicity and is generally believed to reflect the demands of ruminant nutrition: to keep the rumen functioning efficiently as a food supplying fermenting vat, it must be continuously re-supplied by grazing. How rumen fermentation is coordinated with metabolic energy demands and behaviour is an important unresolved issue, with major implications for farm animal health. In this proposal we wish to develop novel 3Rs research approaches allowing a quantitative analysis of the links between two key hormones controlling temporal organization (melatonin and cortisol), production of rumen metabolites (volatile fatty acids – the energy nutrient provided by rumen fermentation) and ruminant behaviour. The key innovation is to develop methodology allowing us to use a portable microdialysis device (U-rhythm), originally designed for medical diagnostics to assay hormone and rumen metabolite levels in freely moving reindeer. To get a comprehensive picture within individual animals, we will marry this novel technology with accepted approaches to assaying activity (actiwatch accelerometers in a collar), and metabolism (subcutaneous body temperature easured using an Anipill datalogger).
2.Distress
Fitting of the U-Rhythm microdialyis device requires subcutaneous insertion of a cannula needle, while implantation of an Anipill data logger requires a small skin incision to be made. These procedures rate as moderate distress, and can be performed under local anesthesia only, in the highly tamed animals. Blood sampling from the jugular vein will cause mild distress.
3.Expected benefit
Mouse / human templates for circadian-dominated behavioural organization are not readily applicable to ruminants, and the planned studies will provide new insights into the roles of rumen metabolites and ultradian hormone (especially cortisol) secretion in organization of activity. The results will have wide relevance in veterinarian and live-stock research directed at improving health, welfare and performance.
4.Animals
Reindeer
5.3Rs
Reduction: This study will develop an approach to be used in small numbers of tame animals, where serial sampling allows individual animals to yield rich information.
Refinement: The approach will use small numbers of tame animals used to human contact from an early age, combined with biologging methods (U-Rhythm, Anipill) in which data can be collected from freely moving animals in controlled semi natural settings. This approach reduces confounding effects of stress, improving data quality.
Replacement: Krogh's principle states: "for such a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied." Norwegian reindeer are ideally suited to study how endocrine and metabolic signals organize behavior because dependent on time of year, there are distinctive periods when behaviour is dominantly ultradian and other periods where diel / circadian patterning dominates.