DYNMOD is a simple tool for demographic projection of tropical ruminant livestock populations. DYNMOD is well adapted for fast and crude ex ante or ex post diagnostics, in various applications as for example livestock population management, herd production estimation or exploration of scenarios in development projects.

Based on simplified demographic processes, DYNMOD simulates the dynamics of the population size and the number of animals produced per year. DYNMOD also calculates live weights, meat production and secondary productions (milk, skin and hides, manure) at population level, as well financial outputs that can be used in more integrated financial calculations (e.g. benefit-costs ratios or internal return rates). Finally, DYNMOD provides crude estimates of the population feeding requirements in dry mater.

DYNMOD predicts what would happen under some hypothetical scenarios, not what will happen in the real world. In that sense, DYNMOD is more a projection model than a prediction model (Caswell, 2001). In a simulation, the user has to judge by itself of the relevancy of the scenario considered.

DYNMOD was developed under Microsoft® Office EXCEL by CIRAD and ILRI. The present version consists in three interfaces:

• STEADY1: simulation of the 1-year population production assuming a demographic steady state – with constant sex-by-age structure and growth rate
• STEADY2: simulation of the 1-year population production assuming a demographic steady state – with constant adult population size and null growth rate;
• PROJ: simulation of the population dynamics and production of a over a period of time in a possibly variable environment (the period can last from 1 to 20 years).

The three interfaces are based on the same underlying demographic model but represent different hypotheses.

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DYNMOD materials

Contact

matthieu.lesnoff@cirad.fr