Behavioural patterns of grazing ram lambs exposed to gastrointestinal nematode parasitism

Nematode parasitism is known to affect animal behaviour. Wearable sensor technologies have the capability of automatically detecting behavioural changes of animals in real-time, which may enable early and timely detection of parasite infection, leading to improvements in treatment protocols. The purpose of this study was to investigate the behavioural changes of grazing lambs, detected with wearable accelerometers, when exposed to an infection challenge of gastrointestinal nematodes (GIN). Thirty-six grazing ram lambs (10 weeks-of-age) wearing Cowmanager ear-tagged tri-axial accelerometer sensors were allocated to one of four groups which were managed as one mob on pasture during a six week infection period. Two groups received a trickle infection with both of the gastrointestinal nematodes Teladorsagia circumcincta and Trichostrongylus colubriformis (OP) while the other two groups remained not infected (NP). After four weeks, one of each of the OP and NP groups was then treated with an anthelmintic, giving rise to four treatments, viz, Infected and treated (OP1), infected not treated (OP2), not infected and treated (NP1) and not infected and not treated (NP2). Compared with non-parasitised lambs, infection reduced live weight gain (P = 0.008), and increased both FEC (faecal egg count) (P < 0.001) and IgA antibody titres (P = 0.011). Compared with their respective NP counterparts, infected animals (OP1 and OP2 until day 28 and OP2 from day 42) showed reduced eating (-91.7 mins/d) and ruminating (-15.5 mins/d) time, increased time spent inactive (+88.4 mins/d), active (+7.4 mins/d) and highly active (+12.7 mins/d). In addition, diurnal patterns of activity were altered by both parasite infection and anthelmintic treatment of infected animals. Compared with their respective controls, drenching of lambs increased eating duration during the daytime and at sunset, while altered diurnal profiles of the time spent ruminating, being inactive and highly active were also evident. This study shows the potential use of on-animal automated activity recording technologies to detect changes in behavioral patterns caused by nematode parasitism in grazing lambs. However, lambs had already suffered lost production before behavioural differences were evident, bringing into question the suitability of these technologies as an early detection tool.