Behavioural patterns of lambs detected with tri-axial ear-mounted accelerometers while grazing endophyte-infected perennial ryegrass

Abstract

The infection of the endophytic fungus (Epichloë festucae var. lolii) within perennial ryegrass (Lolium perenne) pastures can produce toxic alkaloids, including lolitrem B and ergovaline which can negatively impact animal welfare and behaviour through causing ryegrass staggers as well as poor growth and increased sensitivity to heat stress. Wearable 3-axis acceleration sensors can provide an alternative to automatically monitor individual grazing livestock who need essential treatment to minimise the impact of grazing pastures infected with an endophyte. The objective of this study was to categorise changes in ruminating, eating and other behavioural activities of grazing lambs exposed to endophyte-infected perennial ryegrass via commercial accelerometer sensors. Lambs were fitted with the ear-mounted accelerometer sensors (CowManager SensOors, Agis, Harmelen, the Netherlands) and allocated randomly within live-weight strata to graze either endophyte-free (Control) or wild−type endophyte-infected (Endophyte) perennial ryegrass pasture. Live weight change, behaviour and incidence of staggers were monitored over a 2-month grazing period. Moderately severe staggers (score 4/5) occurred in 40% of lambs in the Endophyte treatment with a mean staggers score of 2.33 ± 0.41 across the group. Compared with control lambs, endophyte-infected lambs compensated for reduced eating (−36.0 min/day) and inactive (−43.7 min/day) duration in favour of increased ruminating (+40.2 min/day) and active (+29.9 min/day) duration. The sensors also identified diurnal adaptations in behaviour of lambs which were affected by endophyte staggers, presenting significant effects of endophyte challenge by hour interaction on the diurnal eating duration (P < 0.001), diurnal ruminating duration (P < 0.001), diurnal inactive duration (P < 0.001), diurnal active duration (P < 0.001) and diurnal highly active duration (P < 0.001). In conclusion, these sensors were able to detect subtle changes in the behaviour of grazing sheep that can be used to detect subclinical symptoms of ryegrass staggers when consuming ryegrass staggers.