This is the message from SAC (Scottish Agricultural College) researchers whose latest study found pig aggression is a genetic trait that can impact on welfare, carcass value and meat quality. The findings also open the way for reducing pig aggression through genetic selection.

The SAC-led study was part of the major pan-European SABRE project, published this week. Researchers from SAC’s Animal and Veterinary Sciences Research Group found that pigs with aggressive ‘personalities’ cause more fighting and experience more stress when mixed in unfamiliar groups.

Co-operation with international pig breeding company PIC gave access to a commercial farm. Project partners INRA in France and FBN Dummerstorf in Germany, went on to analyse pig tissue to identify genes linked with aggression, stress and meat quality and how they interact.

Explaining the significance of the findings for the pig industry, SAC Behavioural Scientist Dr Rick D’Eath said: "The mixing of pigs into new groups commonly occurs pre-slaughter. Increased fighting presents an obvious welfare concern and can also reduce carcass value when scratched or damaged areas have to be discarded. In addition, the pigs we studied which experienced stress prior to slaughter had less acidic meat post-slaughter, which can reduce its eating quality.

"Therefore, reducing pig aggression, particularly pre-slaughter, could bring welfare and financial benefits while reducing waste and improving meat quality. Producers, hauliers and slaughterhouses could work together to avoid the mixing of pigs in unfamiliar groups before slaughter, such as by ensuring that farm groups of pigs are penned separately on the truck and at lairage. In the longer term, the study also opens the way for tackling the issue of pig aggression using genetic selection."