When to mix sows in groups?

As farmers in many parts of the world adapt to meeting requirements for housing gestating sows in groups, pressure continues to reduce stall use. Can further limitations on stall use impact sow fertility and production, or are there advantages to be gained from managing sows loose from the time of weaning? In North America stall housing predominates, however some individuals and larger production companies have been incorporating loose housing in both new builds and renovations. In response to