Behavioural and cardiac responses towards different novel objects in juvenile female and male pigs (Sus scrofa)

Abstract

The way in which environmental stimuli affect animals and translate into behavioural and physical responses is of high importance with regards to the animals’ well-being. The aim of the study was, to gain deeper understanding of the relationship between behavioural responses and cardiac parameters. Our study investigated the effect of eight novel objects on the behaviour and the cardiac responses of 9 female and 9 male growing pigs in postnatal weeks 6-9. The novel objects tested were a rope, a soil heap, a Kong®, an experimental glove, a dog intelligence game, a wallow, a rubber duck and a heap of leaves. Every animal was tested twice per object. During novel object tests, the exploratory behaviour towards the objects and the test environment as well as play and tail wagging behaviour were recorded. Simultaneously, heart rate (HR) and further cardiac parameters (SDNN, RMSSD, LF, HF) were measured using the Polar® System. Results show that “complex” objects (soil, wallow, leaves) were explored more than “rigid” objects (rope, glove, Kong®, IQ game, duck; p = 0.01). The novel objects tested had a significant influence on the behavioural traits, as well as the cardiac traits HR and LF (p = 0.001). In general, correlations between exploratory behaviour and cardiac parameters were not significant. We conclude from our findings that juvenile pigs have clear exploratory preferences with regards to the structure of novel objects. There was no evidence of a strong link between exploratory behaviour and cardiac responses.