Dynamic model for ammonia volatilization in housing with partially slatted floors, for fattening pigs

A dynamic model was developed to simulate the ammonia volatilization from pig housing with partially slatted floors, where no litter is used. Simulated ammonia emission levels were compared with measured levels for 1 day in each 3-week period during two fattening periods of 15 weeks (one in winter and one in summer) in each of three fattening compartments. The overall mean ammonia emission measured was 6.84 g d-1 pig-1, while the mean overall simulated emission was 6.36 g d-1 pig-1, with 1.96 g d-1 pig-1 simulated to volatilize from the floor and 4.40 g d-1 pig-1 from the slurry pit. The mean relative difference between the daily simulated and measured ammonia emissions was 16.9%. This was 15.0% at the low and moderate emission levels ( 9 g d-1 pig-1). Simulated effects of different factors corresponded satisfactorily with the measured effects reported in the literature. It is concluded that the ammonia emission from housing for fattening pigs in which the floors are partially slatted can be reasonably well predicted at the low and moderate levels of emission, but is poorly predicted at high emission levels when the solid pen floor is severely fouled at high ambient temperatures

Ammonia emission in a scale model of a dairy-cow house

A scale model of a dairy-cow house was developed for studying factors involved with ammonia emission. The ammonia emission from two different floor fouling methods was measured. In the first case, a urine/feces mixture was applied daily to the floor surface. In the second case, a thin layer of feces was applied daily and urine was sprinkled over it. In both cases, the ammonia emission increased after fouling each day. After seven days the situation stabilized. An ammonia emission peak was always observed within two hours after application of the urine/feces mixture or the urine, while afterwards the ammonia emission rate gradually declined in about 24 h to the level prevailing before the fouling. The second method, which is more comparable to the fouling in a practical cow house, revealed a linear relationship between the height of the ammonia emission peak and the urea concentration of the urine. Measurements at different temperatures and with different air velocities over the floor surface showed that the height of the ammonia emission peak depends on temperature to the power of 0.89 and on the velocity to the power of 0.26

Modelling and experimental determination of ammonia emissions rates from a scale model dairy-cow house

A simulation model was developed to predict ammonia emission from a scale model dairy-cow house. The model described the enzymatic urea degradation and volatilization of ammonia from a slatted floor after applying a mixture of urine and feces or after sprinkling of urine. The parameters needed as input for the simulation model to predict the ammonia emission for a period of 24 h were measured or taken from literature. Lack of fit occurred between the predicted and measured emission when urease-activity values from a laboratory analysis of a urine/feces mixture were used. A better agreement was obtained by using an urease-activity which was about ten times higher. The need for a higher urease-activity is in accordance with the observation that due to repeated fouling of the floor the height of the emission peak measured after the application of an urine/feces mixture increased and the time between the application of the mixture and the moment that the emission reached its peak became shorter. This indicated that due to repeated fouling, the amount of urease on the floor surface increased. The developed simulation model can be used as the basis for a model to predict the ammonia emission from a practical dairy-cow house