Social behaviour in animals is partly genetic. Currently, only the traits of the individual are used for selection. However, selection methods which also include the effect of an individual on its group members appear to be more successful. In an article that was published last week in Frontiers in Genetics, researchers from Wageningen UR put all the existing knowledge together. Breeding with social genetic traits appears promising and may in the future simultaneously improve production and welfare in livestock.
Social interactions between individuals living in a group can have both positive and negative effects on welfare, productivity, and health of these individuals. Negative effects are easier to observe than positive effects. For example, laying hens may develop feather pecking and pigs may develop tail biting. Cooperation and mothering behaviour are examples of positive social interactions. These types of social interactions are partly encoded in the DNA and contribute to the genetic variation that breeders can use to improve their breeds. Genetic improvement of socially-affected traits, however, has proven to be difficult until relatively recently.
The use of classical selection methods, like individual selection, may result in selection responses opposite to expected. For example, laying hens that have good genes for survival could also be more likely to show high levels of aggressive and competitive behaviour, which reduces the survival of their group mates. It has become clear that improvement of socially-affected traits requires selection methods that take into account the social effects of an individual on its group mates. The success of this method has been shown in different studies. For example, feather pecking behaviour in laying hens can significantly be reduced and cannibalism and tail biting in pigs can be diminished.
Livestock are nowadays more frequently kept in (larger) groups, resulting in an increase in social interactions between individuals. Moreover, treatments to limit the consequences of adverse social interactions, such as beak trimming in poultry and tail docking in pigs, will probably be banned in the future, so that the negative effects of social interactions will likely increase unless action is taken to avoid that. The genetic variation and selection tools are available. Nevertheless, successful application in commercial breeding programs faces a number of challenges. For example, livestock do not live their entire lives in the same group and groups are often large which makes it unclear which animals have social contact with each other. Also, many social traits are strongly influenced by the environment, in addition to the genetic aspect. In practice, therefore, improving social traits must be achieved by improving both the environment and the genetics. For improvement of the genetics, expanding genomic selection (the selection of breeding stock on the basis of their DNA) to social traits is a promising approach. This is currently studied in a follow-up project.
On November 21, Naomi Duijvesteijn, one of the co-authors of the article, will defend her PhD thesis 'Sociable Swine: prospects of indirect genetic effects for the improvement of productivity, welfare and quality'. The ceremony starts at 16:00 in the Aula of Wageningen University.
See for more information the announcement.
Read the full article here.