Fig. 1

Type of production in relation to herd size as reported by the 174 surveyed Swedish pig farms. The figure shows 135 sow holdings, including central units in sow pools (small sized if fewer than 100 sows or less than 220 annual farrowings in a sow pool, medium sized if 100–400 sows or 220–880 annual farrowings in a sow pool and large sized if more than 400 sows or 880 annual farrowings in a sow pool) as well as 39 specialised fattening producers (small, medium sized and large when annually producing < 5000, 5000–10,000 and > 10,000 pigs, respectively). SPF: Specific pathogen free