Funder and dates: Walsh Fellowship and the Scottish Government (RESAS RD 2.3.1.), 2015-2018
Collaborators/partners: SRUC, Teagasc, Roslin Institute
Aggressive behaviour between pigs is a major challenge to animal welfare, economic productivity and environmental sustainability. Intense aggression occurs when pigs are regrouped with unfamiliar animals, as common in commercial practice, and thereafter chronic aggression persists even in groups of stable composition. Regrouping and long-term aggression both need to be controlled but vary greatly in expression between individuals and between groups. Recent evidence shows that involvement in aggressive behaviour at regrouping, even if a pig is defeated, may be necessary to minimise the costs to that animal of long-term aggression. At present the optimum compromise between regrouping and long-term aggression has not been defined and the aggressive strategies which underlie an optimum trade-off are unknown. This project is a collaboration between Teagasc, SRUC and the Roslin Institute. It will define the aggressive behavioural phenotypes that simultaneously minimise regrouping and long-term aggression, the genetic basis behind these optimum phenotypes and the economic benefits for productivity and reproductive performance associated with these pigs. The project will utilise a comprehensive aggressive behavioural database of >1000 pedigreed animals. In the first stage of the work, social network analysis has been applied to understand pen-level differences in regrouping and chronic aggression. This approach has highlighted the importance of taking account of the full network of both direct and indirect aggressive interactions between pen mates. Reference to the entire network structure better explains the occurrence of injuries from aggression than simply considering the sum of the direct dyadic interactions between animals. Subsequent work will model the dynamic establishment of social network positions and their genetic basis. Lastly, the effects of different combinations of skin lesions from regrouping and chronic aggression on sow reproductive performance will be assessed.