Behaviour of lambs (Ovis aries) in relation to spatial patterns of defecation on a pasture

Abstract

Twenty lambs (median body weight 37.2 kg) were kept on a paddock of 0.56 ha in England for four weeks in autumn. A 10 m grid was marked out in the paddock and from 10 of the 54 grid squares, all faeces were removed by hand at the start of each week. Faecal abundance was estimated by a point quadrat technique and observations of behaviour were made by scan sampling at intervals of 10 min during 15 h in each week. Each lamb produced on average 0.72 kg wet weight of faeces per day. Removal of faeces had no effect on grazing behaviour and the only correlation between faecal abundance and behaviour was that night lying tended to be on areas where faecal abundance was high. This was probably due to the lambs preferring certain areas for night lying and defecating heavily in these areas before starting to graze in the morning. Faecal encounter during daytime grazing was affected neither by sheep body weight nor by parasite burden. Behavioural mechanisms of avoidance of faeces are probably not detectable when behaviour is studied in the context of grid squares of 100 m2 and further study should include detailed observations on the grazing paths of individual sheep.