AMMONIA VOLATILIZATION AND DUST CONCENTRATION AS AFFECTED BY VENTILATION SYSTEMS IN HOUSES FOR FATTENING PIGS

One way to improve air quality inside houses for fattening pigs is to locate the air inlet near the breathing zones of pigs and the stockman and the outlet near the main source of contaminants, i.e., slatted fl oor and slurry pit This may increase the total emission of ammonia by speeding up the airflow above the emitting area. To investigate this, we compared a ventilation system with the inlet in the feeding passage and the outlet just above the slatted floor (system Fl, with a system common in the Netherlands having a high, diffuse inlet and a high out let (system C). The two ventilation systems were installed in each of two rooms in an experimental house. A layer of oil was used on the slu rry to reduce the volatilization of ammonia from The pit. Ammonia conc entrations, in the air inlet and outlet, in the slurry pit and at anim al level on the solid and slatted floors, and the ventilation rate wer e measured continuously. Dust concentrations were measured 1.5 m above the floor in the feeding passage. The urine wetted area of the solid floor was recorded. We found that system F caused a significant reduct ion in ammonia concentrations at animal level on the solid and slatted floor (P < 0.05) and dust concentration in the feeding passage (P < 0 .001) compared with system C. There was no effect on ammonia emission or on the urine-wetted area of the solid floor due to the ventilation system. We conclude that air quality in houses for fattening pigs can be improved by a low air inlet in the floor of the feeding passage and a low outlet just above the slatted floor and slurry pit, instead of a high diffuse inlet and a high outlet. These locations do not affect the total emission of ammonia to the environment.