Reducing Aggression in Pigs at Mixing by means of Environmental and Genetic Selection Tools

In commercial production systems, abrupt mixing of pigs commonly results in aggression to establish social ranking (Turner et al., 2008). While mixing is beneficial for the producer, enabling batch finishing and space efficiency, significant welfare implications exist (Bracke & Hopster, 2006; Turner et al., 2009). Pigs exhibit physiological stress responses in association with aggression (Arey & Edwards, 1998). In addition to affecting production traits such as daily weight gain and meat quality, aggression typically causes superficial injuries, social stress and impaired immunity (D’Eath, 2002). This paper looks at research into the genetic components of aggression and administering a synthetic maternal pheromone at mixing to enhance welfare.