Short-term effects of early social experiences on reactions to unfamiliar pigs

Sammanfattning: In Europe, there is an ongoing transition from individual housing to group housing for sows and gilts. The two housing systems will meet some of the needs of the sows but fail in meeting others. Individual housing systems can limit the possibility for aggressive behaviours between animals, whereas it fails in providing possibilities for social interaction and relevant space allowance. On the other hand, sows in group housing systems displays more aggressive behaviours but the sows have more space and the possibility to socially interact with other sows. In 2012, Sweden ended the breeding of Swedish Yorkshire (SY) and genetics from the Dutch Yorkshire (DY) was introduced instead. These two breeds have been selected in different environments (group housing vs. individual housing) which may have caused behavioural differences that may be of importance for group housing systems. This Master thesis aim was to investigate social behaviours, body posture, solitary play behaviours and exploratory behaviours of five weeks old gilts and see if there were any differences between the two genotypes (SY and DY). The aim was also to see if behaviours changed between groups depending on if the gilts had the opportunity to socially interact with other unfamiliar piglets during nursing (called access pen (AP)) or if they could only socialise with their own litter and mother (called control pen (CP)). Protocols and ethograms were developed for registering the behaviours in a paired interaction test on 102 gilts for a total of three minutes. The practical study was carried out at the Swedish University of Agricultural Sciences (SLU) Research centre at Lövsta, Uppsala. Which was then observed via video recordings. The results showed some significant differences between genotypes and social treatments, as well as the interaction between genotype and social treatment. Overall, SY gilts were more explorative than DY gilts. SY gilts also initiated the social interaction with more severe behaviours than DY gilts, as well as responding to social interactions with less severe behaviours at a larger proportion of the social interaction. The severity of the interaction was assessed by looking at the responding pigs’ proportion of screaming. Regarding the different social treatments, AP gilts explored their surroundings more than CP gilts. The results also showed that AP gilts performed more severe social behaviours than CP gilts, which was also based on that the responding pigs’ proportion of screaming. Early socialised pigs exhibited aggressive and severe behaviours quicker, but are also assumed to form dominance hierarchies quicker which will reduce their stress and injuries as well as improve their welfare and production.