Short-term stability over time and across situations of behavioural traits in gestating and lactating sows

Personality consists of the set of traits which show stable individual differences in behaviour over time and across contexts in a species. Personality has been previously studied in pigs, however few studies have focused on adult females and on both the gestating and lactating phases of their reproductive cycle. The aim of this work was to identify candidate personality traits in breeding females, by assessing temporal stability and associations between situations. Adult female pigs (Sus scrofa) ranging from parity one to seven underwent a series of repeated tests and observations during late gestation (70-110 days after service) and during lactation (1-30 days after farrowing). In gestation, their response to a human in the home pen (median 2 repeated tests per individual, ranging from 1-4) and social behaviour at feeding (median 2 tests, 1-4) were assessed. In lactation their response to a dummy hand (median 2 tests, 1-4) and lying down behaviour (median 2 tests, 1-6) were recorded as indicators of maternal defence and maternal care. Out of the twelve variables measured in these four different situations, five were consistent over repeated tests at different times (i.e. the posterior distribution of their repeatability excluded values less than 0.01): dominance rank, number of attacks, and number of avoidances during feeding, number of vocalisations when exposed to a dummy hand, and probability of vocalising before lying down. We found correlations with an absolute value higher than 0.30 between number of attacks and number of avoidances during feeding, number of attacks and number of vocalisations when exposed to the dummy hand, and between the latter and probability of vocalising before lying down during lactation. Our results suggest that social behaviour at feeding and acoustic signalling in different contexts are stable traits in adult female pigs. The estimated correlations between the traits might also indicate the presence of a proactive behavioural syndrome.