Gilts response in behaviour tests : investigation of differences between two genotypes

Sammanfattning: When the breeding with the Swedish Yorkshire (SY) breed ended in 2012, the Dutch Yorkshire (ZY) breed was introduced to Swedish pig producers. Swedish farmers have noticed behavioural differences between SY sows and ZY sows. Different breeding goals and selection environment for the two breeds (different production systems, e.g. single or group housing systems) and different management could cause such behaviour differences. Some behaviours of importance in pig production are aggressive behaviour towards unfamiliar pigs, response towards handling and adaption to environmental changes. The aim of this MSc thesis was to assess differences in reaction in behaviour tests between the breed crosses SY'Hampshire (H) and ZY'Hampshire (H). In total, five behaviour tests were performed: a back test, a human approach test, a novel object test, a suddenness test and an intruder test were performed on 60 gilts in three different age categories (20 individuals in each category): at 10-21 days of age, at 2.5 months of age and at 5 months of age. Half of the gilts were crossbreed SY'H and the other half were crossbreed ZY'H. The SY'H gilts had a tendency to adapt their behaviour patterns towards changing stimuli more easily. In addition, the ZY'H gilts showed tendencies to be more fearful of humans than the SY'H gilts. Knowledge about the behavioural differences between the breeds and the biological background of the differences are important to take into consideration in order to adapt management to the animal material being used.