Electronic sow feeder (ESF) systems are a practical method for managing sows in group housing, as they provide an automated system for controlling individual feed intake. However, increased aggression can result, especially in the initial period following mixing, as sows compete for access to the ESF. The primary objective of this research was to compare different methods for grouping sows housed in static ESF systems, in order to assess differences in their effects on feeding behaviour, sow injury, and production. Sows were housed in groups of mixed parity (control), low parity (parities 2 & 3), medium parity (parities 3-5), and high parity (≥ parity 4). Within this framework, we compared measures of feeding behavior, sow well-being and productivity among high, medium and low parity sows in uniform versus mixed groups. Of specific interest was whether low parity (1 and 2) sows experience less aggression and injury during gestation when managed in uniform groups than in mixed groups, and what effects these treatments may have on production measures at farrowing and backfat.
The preliminary results presented here indicate that housing sows in uniform groups produced some benefits, especially for younger sows. Sows in uniform groups had reduced lameness following mixing compared to mixed groups. Increases in backfat over gestation showed that younger sows fared better in uniform groups. Young (parity 1 and 2) sows were able to increase backfat in uniform groups, as opposed to loosing it in mixed groups, suggesting that competition at the feeder was less of a challenge in the uniform group. No production differences were found between sows in uniform groups as compared to mixed groups. Managing gilts as a separate group is already a common practice, and results from this study suggest that parity 1 and 2 sows can also benefit from this practice. Maintaining uniform groups also helped to reduce mixing injury, with injuries sustained following mixing being equal to or lower than the mixed parity groups, with only the low parity uniform group having higher injury scores. However, greater injuries in younger sows is more likely related to the social ability of these animals, and management of gilts to improve sociability may be a further management consideration that could be implemented.