Understanding Aggression using Pre-Exposure in Mixed Sow Groups

October 3, 2012 — 

We know that sows will fight when mixed and when having to compete for access to resources. However, there is little information on the effects of pre-exposure when sows are mixed together. This project aimed to investigate whether housing sows next to each other in the service house (pre-exposure) would influence the amount of aggression observed when they were subsequently moved into group gestation pens. Results from our experiment showed: total body lesion scores were significantly higher for pre-exposed sows in the 35-day experiment and numerically higher in the 7-day experiment. In both experiments, significantly more lesions were seen around the head, neck and shoulders of the sows, indicative of pre-exposed sows engaging in more reciprocal fighting behavior. Detailed analysis of the behavioral data is ongoing, but time-budgets indicated no effect of treatment during the early post-mixing period. Closer examination of aggressive behavior so far has shown no significant differences between treatments in aggression, but many of the measures show numerically higher numbers for pre-exposed sows. There is also no effect of treatment on production, with sows in both experiments having similar total litter sizes and numbers born alive and dead. Overall, the study has shown that pre-exposing sows to each other in service crates prior to mixing appears to be disadvantageous at subsequent mixing.

Key Points:
• Mixed groups of sows often fight
• “Pre-mixing” would seem beneficial
• Experiments show no benefit to pre-mixing of sows
• Results indicate mixing of “non-neighbor” sows works best

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Principal Researcher: Jeremy Marchant-Forde., USDA- ARS

Source: Pork Checkoff research Review September-October, 2012