Twenty-six experimental studies of ammonia emissions from pig buildings that utilise
some form of pit/slurry system have been analysed and compared. Using standard values
for pig weight and total Kjeldahl nitrogen (TKN) content in the waste when these quantities
were unspecified, experimental ammonia emissions were compared on a per cent loss
(of excreted TKN) basis. Correction factors were determined for measurements made
during specific parts of the year, with corresponding differences in temperature, or time of
day, and adjustments were made to put emission data on an annual average basis, when
applicable. When corrected in this way, measurements made in the United States and in
Europe were 22% and 21%, respectively. The standard deviation and standard error of the
mean were 9% and 1.8%, respectively. The 95% confidence interval of the mean was
17.6–24.9%. The proposed emission factor data are reasonably consistent and emission
factors higher or lower must be critically compared to the existing experimental base.