Using network flow modeling to determine pig flow in a commercial production system

The systematic approach to raising pigs in a multi-site production system, in terms of where the pigs are housed and how long they are fed, is generally called pig flow. This complex process is most often approached in a segmented fashion, not looking at all barns at the same time in relation to each other. Linear programming, the basis of most nutritional formulation packages and logistics services, provides a mathematical means for characterizing pig flow that allows a producer to look at the entire flow of pigs in a system at the same time. We describe a teaching model that provides the foundation to characterize pig flow in a commercial production system. The teaching model is built in Microsoft Excel® and incorporates key components of production such as growth rate, mortality, stocking density, seasonality, packer grid pricing, and marketing. The results from this teaching model are sound and provide the foundation for a larger model that is needed for full implementation within a production system, proving this model behaves as expected. The generalizability of the model and its assumptions allows for the inclusion of more barns, a more precise measure of time, and the ability to change the assumptions utilized in this teaching scenario, which are needed for direct application in a production system.