Environmental aspects of improving sow welfare with group housing and straw bedding

After intensifying pig husbandry in the second half of the 20 ^th century to improve economical development, public concern brought about legislation to secure animal welfare and ecological values.The development of welfare-friendly sow husbandry in recent years focussed mainly on two purposes: to keep sows loose in groups and to provide the sows with straw bedding. The main objective of this research was to establish the effect on ammonia emission of group housing and straw bedding, and eventually to find tools to reduce the emission. With straw bedding, the greenhouse gases methane and nitrous oxide were also considered, because environmental goals are not served by pollution swapping.

The results showed that group housing of sows does not increase ammonia emission compared to individual housing of sows. Given appropriate straw management, providing a straw bed reduces ammonia emission, and emissions of methane and nitrous oxide are not substantial. However more research is needed in order to understand the conditions for low greenhouse-gas emissions. Although the measured effect was modest, shifting feeding time might be a tool to reduce ammonia emission. A model was developed to estimate ammonia emission from a sow house with group housing and straw bedding as the sum of the emissions from straw, solid floors, slatted floors and pits after urinations. The results of simulations show that measures to reduce ammonia emissions are most effective if aimed at decreasing the emission from the solid floor and stimulating relatively more urinations on the straw bed. The model appeared to be a useful tool for designing straw-bedded sow group-housing with low ammonia emissions.