The public concern related to the potential for water and air pollution from swine facilities demands that alternative management practices be developed. Dietary manipulation offers a potential method to reduce nutrient excretion by swine. Results from this experiment suggest that lowering crude protein by four percentage units with amino acid additions and fiber addition can reduce total nitrogen excretion by 35%. Furthermore, using a pilot scale facility, ammonia emissions from manure produced from pigs fed a low protein, amino acid supplemented diet with fiber addition was reduced slightly when loading of manure was based on equal total nitrogen. Taken conversely, these results show that if loading is based on an organic matter basis, which is generally the case, changing from the conventional diet to the fiber fortified low protein, amino acid supplemented diet will result in an approximate 50% reduction in ammonia emissions. However, carbonaceous gas emissions from manure produced by pigs fed the fiber fortified low protein, amino acid supplemented diet increased. This increase was primarily due to an increase in methane emissions when loading was based on an equivalent nitrogen basis. While these results demonstrate the marked effect that diet can have on ammonia emissions, more research is needed to clarify the effect of diet on methane and carbonaceous gas emissions.