The Ammonia Gas Emission Model for Swine (AGEM-S), a nitrogen flow model, was created with the objective of assisting in the reduction of ammonia emissions in the Hungarian pig sector. Regarding the applied technological processes and considering the factors that influence ammonia emissions, the model quantifies the amount of ammonia emissions of pig farming in all stages (feeding, housing technology, manure storage, and application in the field). The aim of the project was to create a system that performs general calculations using the input data used by practicing farmers, without compromising the information content of the output data. Using this system, the input parameters can be entered as simply as possible and in the shortest possible time. In addition to demonstrating the impact of ammonia emission reduction measures to farmers from an integrated N management approach, AGEM-S has the potential to support the transfer of emission reduction technologies and practices at the farm level as a knowledge transfer tool primarily, but also as a decision support tool for technological change.

The effects of feeding low-protein (LP) diets and the age and genotype of fattening pigs were evaluated in an N-balance trial. Sixty weaned piglets of two genotypes were allotted to three different diets. Besides the control diets for the crossbred Topigs 20 × DanBred Duroc (TD) and Hungarian Large White (HLW) pigs, two LP diets were fed containing 1.5 (T1.5) and 3% (T3) less dietary protein than the control. The LP diets were supplemented with crystalline lysine, threonine, tryptophan, and methionine to equalize their digestible amino acid contents. Starter diets were fed between 20–30, grower I between 30–40, grower II between 40–80 and finisher between 80–110 kg live weights. Pigs were kept in floor pens, with 10 animals per pen. In all phases, six pigs with similar live weight were placed into individual balance cages and in the frame of a seven-day long balance trial, the daily N-intake, fecal and urinary N-excretion were measured. From the data N-digestibility, the total ammoniacal nitrogen (TAN) and N-retention were calculated. All the investigated main factors, the genotype and age of pigs and the protein content of the diets had significant effects on the N-balance of fattening pigs. The determinacy of the factors depended on the investigated parameter. Fecal N-excretion and N-digestibility were steadier compared with the urinary N-exertion and TAN percentage. N-digestibility increased and the urinary N-excretion decreased when LP diets were fed. The urinary N-decreasing effect of LP diets was not linear. Compared with the control (19.6 gN/day), T1.5 treatment resulted in 14.5, treatment T3 in 12.4 g daily urinary N-excretion. The TAN and the N-retention of HLW pigs were more favorable than those of TD pigs. Based on our results, it can be concluded that the accuracy of the nitrogen and TAN excretion values of pigs, used in the calculation of the national NH₃ inventories, could be improved if the genotype, the more detailed age categories and the different protein levels of feeds are considered.

In Hungary, there is a lack of information on the pig production technologies in place in the base year of 2005 and changes since then, as well as a lack of information on the number of pigs kept in different age and production categories, which makes it difficult to calculate ammonia emissions and reductions in the national inventories. Our research team conducted a representative survey of pig farms to assess housing and manure management technologies in the Hungarian pig sector in 2005 and 2015. Novel expert-based calculation methods were developed to convert farm data on pig populations into daily average numbers (DAN) of animals in different statistical categories and feeding phases. The survey resulted in a representative database of housing, manure handling, storage and manure application practices in Hungarian pig production. The data and methodology from the survey helped to develop an ammonia emission calculator and knowledge transfer tool (AGEM-S) for use by farmers.

In this trial, the effects of different nutritional treatments on the N balance parameters of fattening pigs in the 55–65 kg live weight category were evaluated. The following diets were used: control diet (C) and low-protein (LP) diet with 2% crude protein reduction, with and without 10% sugar beet pulp (S) or 0.5% benzoic acid supplementation. Six pigs per treatment with similar live weight were used, and in the context of the balance trial, the daily N intake, fecal and urinary N excretion and the pH of urine were measured. From the data N digestibility, the TAN % and N retention were calculated. Feeding LP diets reduced the fecal, urinary and total N excretion and also the pH of urine significantly compared with the control diet. Sugar beet pulp significantly increased the fecal N excretion and urinary pH, and it also reduced significantly N digestibility and the TAN ratio. Benzoic acid failed to reduce urinary pH. The measured N excretion, retention and TAN excretion values were more favorable than those that can be found in the different guidelines or those used in the Hungarian ammonia emission inventory.