Modelling as a tool for the teaching of livestock dynamics

摘要

Modelling is a way of integrating and formalising the knowledge about how a system works. Thus, it is a relevant approach for teaching agricultural systems analysis to undergraduate students. In most cases, research models or decision support tools cannot be easily used for teaching purposes because conceptual models are too complex to be handled by students during a short training course or do not fit pedagogic goals. However, from our own modelling research, we developed two techniques to support our teaching program in herd dynamics. The first one was based on a deterministic approach and used simple flow diagrams. Students had to fill in a paper chart that depicts the breeding scheme of a flock for several years. Thus, they test if a combinationof decision rules (e.g., breeding, replacement, culling) allows to reach a given production objective. Then, students had to suggest technical means or management decisions that could improve flock productivity. The second technique relied on a stochastic matrix model that was used to illustrate the sensitivity of herd productivity in a tropical environment. The model was computerised using spreadsheets. On the basis of the simulation results, students had to comment on the behaviour of the system andto appraise the model, with respect to the choice of assumptions and formalisation. Because our teaching approach is progressive and interactive, we are confident that students will become well-informed users of more elaborated models such as decision support tools.