Dynamic Simulation Model of Nitrogen Fluxes in Pig Housing and Outdoor Storage Facilities

Many factors in pig production, including genetics, feeding efficiency, feed composition, feed distribution method, environmental control, and waste management, affect the nitrogen content of pig slurry. However, estimating the global impact of these factors on the nitrogen (N) content of daily fresh manure and stored slurry is not easy. Mathematical modelling of certain N fluxes in pig production systems have shown good potential for predicting the impact of some of the aforementioned characteristics on either pig excretion or ammonia volatilisation in buildings and outdoor storage facilities. However, none considered both excretion and ammonia volatilisation over the entire production site. To do this, equations from the literature were used to construct a dynamic simulation model of N fluxes in both batch and continuous production systems. The resulting model allows for prediction of daily concentrations and quantities of N in buildings and storage facilities. Total N concentration in outside slurry tanks can be accurately predicted within an error range of 6·4% for the growing-finishing site and 9·3% for the reproduction site.