Sow welfare legislation has meant that many dry sows are now housed in large dynamic groups. The large group sizes involved in these systems and the constant turnover of sows does not allow stable relationships to be formed and so leads to agonistic behaviour (Moore, Gonyou and Ghent, 1993). The aim of this study was to determine if pre-mixing weaned sows in small groups for five weeks prior to introduction into the large group would reduce the overall level of agonistic behaviour.

Sixteen groups of four newly weaned and unfamiliar sows were allocated at one week intervals to one of the following treatments. Treatment 1 (T1) involved introducing sows into small static groups of four for a period of 5 weeks prior to introducing them into a large dynamic group. Treatment 2 (T2) involved introducing sows directly into a separate large dynamic group.