UK - Pigs and poultry farm practices survey 2009

• 79% of holdings with outdoor pigs use a site rotation system with an average of 17 months being spent in a paddock before rotation.
• 35% of holdings with pigs are part of a pig breeding pyramid.
• The majority of pig slurry is stored either in cellars, pits or channels beneath livestock housing (38%) or in unlined earth bank lagoons (30%).
• A large proportion of farmyard manure (FYM) is stored in the open with 56% of FYM being stored in the open with no constructed base and 33% of FYM being stored in the open on a concrete base.
• 46% of pig holdings use contractors to spread their farmyard manure or slurry.

http://www.defra.gov.uk/evidence/statistics/foodfarm/enviro/farmpractice/documents/FPS2009-pigspoultry.pdf