Sensing the worms : automated behaviour monitoring for detection of parasitism in grazing livestock

Abstract: Gastrointestinal nematodes (GIN) are common in grazing livestock and is a major cause of impaired health and productivity. Current control practices of GIN infections depend largely on the use of anthelmintic drugs. However, misuse of anthelmintic drugs has led to a widespread development of anthelmintic resistance. Behavioural monitoring has been suggested as a novel method to detect parasite infection in grazing livestock, enabling targeted (selective) treatment, where only infected groups or individual animals within a group are treated. The aim of this thesis was to investigate how multispecies GIN parasite infections affect behavioural patterns in grazing livestock on a group level using different on-animal sensors. The effect of subclinical GIN infection on activity and rumination patterns in first season grazing steers were investigated in contrasting groups during two grazing seasons, using different commercial sensors. The results indicate that untreated steers exposed to a higher GIN level had an increased lying time, lower activity level and affected rumination patterns over time, compared with dewormed steers. To enable the assessment of behavioural responses in lambs, the validity of two sensors for cattle for use in lambs were first evaluated. The effect of subclinical GIN infection on activity in lambs around weaning was then investigated in a replicated grazing trial with treated and untreated groups. The results indicate untreated lambs had a shorter daily lying time over time as well as a lower activity level, compared with dewormed lambs. In conclusion, this thesis supports that behavioural patterns are affected by subclinical GIN infections and the results demonstrate the potential use of automated behavioural observations as a diagnostic tool.