The mixing of unfamiliar sows usually results in fighting which can have adverse consequences for both welfare and production. It has been suggested that aggression may be moderated by both the presence of a boar and by allowing sows access to feeding stalls (Arey and Edwards, 1998). The objective of this experiment was to investigate these effects on the behaviour of newly weaned sows mixed into two loose-housing systems.

In the first system (dynamic), 24 Large White x Landrace mixed parity sows were introduced 4 days post weaning to a dynamic group of 22 sows and 2 boars with a replacement rate of 2 sows per week. Observations were carried out on the 2 newly introduced sows each week. The straw-bedded pen provided 4.5 m2 space per animal. The sows were floor fed 3 kg/sow at 08.00 each day.