Effect of sampling order on the salivary cortisol level of group-housed pigs

The aim of this work were to study, in the final stage of fattening of animals accustomed to contact with people, the influence of the saliva sampling order of group-housed pigs and that of the multiple saliva sampling to a particular animal, also group-housed, on the level of cortisol in saliva of fattening pigs. For this, on the one hand, samples of saliva were taken in the morning and in the afternoon to 144 pigs weighing 100 kg, 72 entire males and 72 females, housed in single sex pens (six pigs/pen, 1.2 m(2)/pig), controlling the sampling order (first to sixth) within each pen; on the other hand, in the morning, saliva samples were collected from 24 pigs weighing 100 kg, entire males and females, housed in four single-sex pens (six pigs/pen; 1.2 m(2)/pig), in three different moments, in the same order at all times: minute 0, minute 10 and minute 30. The concentration of salivary cortisol was not affected by the sampling order in each pen, both in the morning (p = 0.7089) and in the afternoon (p = 0.2292). On the other hand, there were no significant differences between cortisol levels in saliva at minutes 0 and 10 (p = 0.4856) nor between levels at minutes 0 and 30 (p = 0.3838 ) or between levels at minutes 10 and 30 (p = 0.1447). In the conditions of our study, neither the order of sampling of saliva to group-housed pigs nor multiple saliva sampling to a particular animal, also housed in a group, influenced the level of salivary cortisol of fattening pigs. These results support the idea that saliva collection is not stressful for pigs.