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Energy & Protein Model





Project Title: Modelling the energy and protein dynamics of Rangifer.

The purpose of the energy-protein model is to predict changes in the body condition of caribou in response to changes in environmental conditions and human disturbance. The model predicts the daily body weight and body composition change of a caribou cow, her milk production and the daily body weight change of her calf as a function of energy and nitrogen intake. Key inputs to the model include the availability and quality of forage, diet of the animal, activity budgets and snow depth.

The model begins by calculating the cow's food intake and then simulating the functioning of the cow's rumen and her digestive kinetics; this determines the metabolizable energy and nitrogen intake of the animal each day.  The activity budget of the animal, along with its reproductive status and the depth of snow in the winter, is used to determine its daily energy and protein requirements for activity and maintenance, base nitrogen, gestation and lactation. Comparing the animal's requirements to its intake each day, the model can then predict the daily change in fat and protein reserves of the animal.



NRG model_output






Through the support of CARMA a number of modifications are currently underway with the model, including the following: 
- revised equations to track the intake and allocation of protein;
- improved user interface for setting model inputs, running the model, and viewing output;
- development of a spreadsheet tool to assist users in parameterizing the model for additional herds;
- added ability to handle uncertainty in parameter estimates through stochastic (i.e. Monte Carlo) model runs;
- development of a linkage betweent the model's body condition predictions and population (i.e. herd) level effects;
- full documentation of all model equations.

The revised model is being developed in Microsoft VB.NET and the code will be published in open source format. 






The model has been applied to examine the impacts of industrial development and climate change on a number of North American herds. This application will be expanded as new research and herd specific data is available. Currently the model is being used to examine the cumulative impact of development within the range of the Bathurst Caribou Herd.





Russell, D. E., R. G. White and C. J. Daniel. 2005. Energetics of the Porcupine Caribou Herd: A computer simulation model. Technical Report series No. 431. Canadian Wildlife Service. Ottawa, Ontario, 64 pp.

Murphy, S.M., D. E. Russell, and R.G. White. 2000. Modeling energetic and demographic consequences of caribou interactions with oil development in the Arctic. Rangifer, Special Issue No. 12: 107-109






Don Russell
Yukon College
Box 10038, Whitehorse, YT Y1A7A1
don.russell 'at'


Robert White
Emeritis, Institute of Arctic Biology
University of Alaska Fairbanks,
Fairbanks, AK 99701
Ffrgw 'at' 



Colin Daniel
Apex Resource Management Solutions
ph: 613.729.9871
fax: 613.822.5674
colin.daniel ' at '