Difference in general behaviour and social interactions of young Yorkshire gilts in different social environments

Abstract: In Sweden, there was a switch of breeding material for pigs in year 2012 where Swedish producers were introduced to the Dutch Yorkshire (DY) instead of the Swedish Yorkshire (SY). Gestating sows have, in Sweden, been kept in group housing since the 1980s while DY gilts on the contrary have been kept in individual stalls. Consequently, the genetic selection of these lines of Yorkshire pigs was conducted in different environments and are thus indirectly selected for behaviours beneficial for each respective environment. This may induce behavioural differences between them, which may be of importance in group housing systems. In the wild, piglets usually have the opportunity to socialise with other pigs outside the litter and piglets that can socialise outside the litter have better social skills later in life. Piglets that do not have the opportunity to engage in social interactions outside the litter may behave differently than piglets that have that opportunity. This Master thesis is a part of an ongoing project “Improving sow welfare in group housing systems” which aims to develop commercially relevant and sustainable breeding and rearing strategies for sows in group housing systems. The aims of this MSc thesis were to investigate if there is a difference in behaviours and social interactions between young gilts with two different lines of Yorkshire breeds and if the behaviours and social interactions are affected if they have the opportunity to socialise outside the litter during an early socialisation period. Direct observations where performed on 118 gilts where half were of the breed SY (49 gilts) and the other half DY (56 gilts). Approximately half of both breeds had access to the neighbouring pen during the last four weeks of the nursing period. Scan sampling was used to record different variables for body position, location in pen and activity. Continuous observations were performed for two minutes per animal on each observation occasion to record social interactions and stereotypes. Overall, the results displayed some behavioural differences between both breeds and treatments. In general behaviour, SY gilts were more active than DY gilts. In addition, gilts of the breed SY performed more social nosing and nosing belly region then DY gilts. Regarding receiving pig behaviour, gilts of the breed SY responds to a performing pigs’ social interaction with no reaction in a larger proportion of the observation occasions in comparison with gilts with the breed DY. Regarding different treatments, gilts held in an access pen (AP) slept less and were more active directly after weaning (when the pop holes were closed). It was also found that AP stimulates the gilts to perform a larger variation in social behaviours and showing different types of behaviours to a larger extent. The largest differences in behaviours occurred around weaning. This study includes the first steps of mapping differences in behaviours during early socialisation between these breeds and treatments, but further studies need to be done on the long-term effects.