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Many important characteristics in swine production such as genetics, feeding efficiency, feed content, feed distribution methods, environment control, and waste management systems affect nitrogen content of liquid manure. However, it is not obvious to estimate the impact of these characteristics on the daily fresh manure production and characteristics per animal unit. Simulation of nitrogen fluxes in swine production systems using mathematical models have shown potential impacts of some the aforementioned characteristics on either swine excretion or ammonia volatilization in buildings and outdoor storage facilities. Here, we used already published mathematical sub-models to construct a dynamic model simulating nitrogen fluxes in both batch and continuous production systems. The resulting model allows for prediction of daily concentrations and amounts of nitrogen inside buildings and storage facilities. The model has been validated using data from a farrowing building of approximately 800 sows and a growing/finishing building system of approximately 5000 hogs. Characteristics of both production sites were obtained using a survey and direct measures were taken (ambient and slurry temperatures, ammoniacal nitrogen and total nitrogen in slurry and slurry pH). Sensitivity analysis confirmed the already acknowledged importance of feed content and methods of distribution - information that can be easily obtained from producers and, thus, should allow for determination of regional amounts of nitrogen produced by swine production systems (e.g., municipality, county or watershed level). Also, the sensitivity analysis confirmed the importance of production system characteristics such as slurry pH and air speed over slurry - characteristics that are seldom known to producers or farm managers. (Download PDF)    (Export to EndNotes)