Ammonia emission from houses for growing pigs as affected by pen design, indoor climate and behaviour

The ammonia volatilization in pig houses should be reduced to protect the environment and to improve the air quality inside the house. The objective of this study was to examine the effects of various housing factors and animal behaviour on the ammonia volatilization in houses for rearing and fattening pigs. The study was intended to yield ways that pig farmers could reduce the emission of ammonia by combining effective and economic housing measures. A marked increase was found in the ammonia emission during the growing period of the pigs. Ammonia emission was generally higher during the summer than the winter season and was positively related to the urine-fouled floor area and the frequency of urination. Reducing the slatted floor and slurry pit area and using slatted floors of smoother material and with more open space than concrete slatted floors, lowered the ammonia emission. The air quality was improved by using a ventilation system with a low air inlet in the floor of the feeding passage and a low outlet just above the slatted floor, instead of a high diffuse inlet and a high outlet. The ventilation system did not affect the total emission of ammonia. The ammonia emission could be reasonably well predicted with a dynamic numerical model at the low and moderate levels of emission, but was poorly predicted at high levels of emission. It is concluded that by combining simple housing measures it is possible to reduce appreciably ammonia emission from houses for growing pigs at relatively low costs. Furthermore, animal welfare and health and the working conditions of the stockman can be improved by these measures.

Ph.D. thesis, Institute of Agricultural and Environmental Engineering (IMAG-DLO), department of Livestock Engineering, P.O. Box 43, 6700 AA Wageningen, the Wageningen Institute of Animal Sciences (WIAS) and the Department of Agricultural Engineering and Physics of the Agricultural University Wageningen.

This study was financially supported by FOMA (Financieringsoverleg Mest- en Ammoniakonderzoek). Their contributions are gratefully acknowledged.