Investigating aggressive temperament in pigs
When pigs are mixed into new groups, they show aggressive behaviour such as fighting and bullying towards unfamiliar animals. This occurs from a young age and at similar levels in males and females. Personality/temperament is important: there are differences between individual pigs in their propensity to show aggression (aggressiveness) which are stable across contexts and over time. Aggressiveness measured in standardised tests such as the resident-intruder (R-I) test predicts aggression in a group mixing situation and in repeat-testing studies aggressiveness (either in R-I tests or group mixing) shows a degree of stability over several weeks. Aggressiveness does not appear to be related to other aspects of temperament such as the response to being handled by humans. Quantitative genetic studies show that aggressiveness is moderately heritable. However, in common with many other complex (e.g. behavioural) traits, a genome-wide association study did not reveal any genes of large effect, suggesting it is a polygenic trait. As in other mammals, the vasopressin and serotonin neurochemical systems vary between pigs of different aggressiveness, suggesting various candidate genes. We are working with commercial pig breeding companies to investigate different approaches for genetic selection to reduce aggressiveness.
Other Titles/Title of Conference
International Society for the Study of Individual Differences, London, UK