Researchers from Scotland's Rural College (SRUC) have been awarded £580,000 to study possible ways to reduce pig aggression, to improve welfare and the economic benefits to farmers.
The team will look at the way the animals fight, specifically on how they settle contests on first meeting. The U.K.'s Biotechnology & Biological Sciences Research Council (BBSRC) has funded the project to help try to decrease this persistent problem.
Pig aggression is difficult to tackle and can cause major reduction in growth rates, an announcement said. Fighting among animals increases significantly when they are mixed in unfamiliar groups. Mixing occurs a number of times throughout a pig's life and is often necessary due to economic constraints facing farmers.
Simon Turner, SRUC senior researcher who is leading the project, said, "Pigs are going to be mixed over the course of their lives a number of times. Changing that is just not practical so over the years researchers have tried to change the pigs' environment, adapting it so they will react less aggressively when mixed. However, these changes, such as adding straw, mixing the animals at night and tranquilizing them, have not worked in the long-term."
Pigs have a strict social hierarchy, when they are mixed with unknown animals they need to form this hierarchy, resulting in aggression. The researchers believe that if they can work out how the pigs think, how they assess their fighting abilities and whether they can make sensible decisions on when to give up, practical ways can be found to manage pigs that will reduce aggression.
"Humans are able to assess both their own fighting abilities, and those of their attacker," Turner said. "There is evidence that some species can do one or the other, but not both. We know little about how pigs make decisions on who to fight and when to give up, but this knowledge will probably prove to be essential in designing management systems that are effective in reducing the welfare and economic costs of aggression."
Therefore, the key to reducing aggression could be allowing pigs to form their natural hierarchies in as painless a way as possible making them far calmer during mixing.
"We need to help pigs realize when it would be sensible not to engage in aggression, because their opponent is likely to beat them," Turner said.
Areas of investigation include whether mixing pigs at a younger age could reduce their aggression when mixed later in life.
In separate work, the researchers will also explore how much a pig's genetics play in how aggressive they are and whether selective breeding could help address the issue.
Turner said, "At the end of these projects, we hope to be able to offer better advice on how to manage and breed pigs in ways that will help the animals make the best decisions for their own welfare, and so reduce aggression."