EVIDENCE FOR THE ROLE OF THE SHEEP-BITING-LOUSE BOVICOLA-OVIS IN PRODUCING COCKLE, A SHEEP PELT DEFECT

The prevalence and severity of cockle, a sheep pelt defect characteris ed by raised lumps, was assessed on lambs that were either louse-infes ted (Bovicola ovis) or louse-free at birth. Assessments were made on p ickled pelts, 10 months after the lambs had entered the trial. Lambs k ept free of lice did not develop cockle, whereas the defect was common in lambs (about 90%) that were infested with lice. There was a direct correlation between louse scores and cockle, high louse scores being associated with a more severe degree of cockle. The results give suppo rt to the strong causal relationship between B. ovis and cockle, but q uestions such as the minimum number of lice needed to cause cockle and the time required for cockle to develop still need to be answered.