Pig behaviour in GxE study using social foraging paradigm

An animal’s genotype, as well as the environment, are known to have an impact on animal behaviour, but the potential genotype-by-environment interactions have received little attention in behavioural studies. The aim of this study was to investigate behavioural differences in crossbred pigs based on commercial genetics and indigenous breeds, housed either in a barren or enriched environment. We investigated measures of fearfulness, persistence and motivation to engage in a social foraging paradigm (the joint-log-lift task) while accounting for coping strategies. Pigs (n = 102), housed across 24 groups of 4-5 pigs, were tested twice in a backtest pre-weaning (at 2 and 3 weeks age). Between 9-11 weeks of age, they were tested once in a joint-log-lift task. We recorded the latency to touch the test device, their engagement with the test device and agonistic interactions. Data were analysed in mixed models with genotype, environment, and their interaction as predictor variables, while accounting for sex, body weight, coping style and group effects. Results showed that pigs approached the novel apparatus within 5 ± 4.2 s (mean ± SD) and remained engaged with the device for approximately 50% of the 15-minute test duration. Neither the duration of engagement nor the proportion of time spent manipulating the device was affected by genotype, environment, or their interaction. Overall, 32% of pigs successfully lifted the log together and obtained a reward. Solo and joint task engagement, and agonistic behaviour were not influenced by genotype, environment, their interaction. Greater task persistence was associated with increased agonistic behaviour, particularly among lighter pigs, although this relationship was unrelated to within-pen body weight ranking. Females tended to engage with the task for longer than males. In conclusion, social foraging behaviour in the joint-log-lift task is relatively robust to the genetic and environmental contrasts examined in this study, with individual behavioural variation playing a greater role than genotype-by-environment.