How group housed
sows are managed can have an impact on their welfare during gestation. The present study examined the effects of housing
management (static vs. dynamic), stage of gestation at introduction, familiarity within the group, and age of sow on some
aspects of the behaviour and physiology of sows in an electronic sow feeding system. Eight groups were introduced into
either a static or dynamic management system. Within an introduction group, 21 to 23 focal sows were selected based upon
their stage of gestation (pre vs. post-implantation), familiarity with groupmates (familiar vs. unfamiliar) and parity [young
(1st parity) vs. intermediate (2nd and 3rd parity) vs. old (4th parity and higher)]. The aggression at mixing, aggression at
the feeder, injuries, feeder entry order, lying patterns, and salivary cortisol concentrations were recorded. There were no
differences in the behaviour or physiology of sows housed in either housing management system, or based upon familiarity.
Sows mixed post-implantation were less aggressive (P=0.01), entered the feeding station later (P=0.03) and were
observed lying in the least preferred areas of the pen (P=0.001), than sows grouped within a few days of breeding. Older
sows were involved in more aggressive encounters (P=0.04), spent more time fighting at mixing (P=0.02), and lay against
the wall more (P<0.001) than did young sows, which tended to sustain more scratches (P=0.07), and ate later in the feed cycle (P<0.001). A dynamic management system is just as effective as a static management system when certain management criteria are met. Familiarity does not have an impact on the sows during gestation. Stage of gestation and parity should be considered along with the group dynamic as it can impact aggression and access to resources.