PRELIMINARY INVESTIGATIONS INTO THE ETIOLOGY AND TREATMENT OF COCKLE,A SHEEP PELT DEFECT

A defect of sheep pelts known as cockle, detectable after depilation, but usually first noted only in the pickled pelt or tanned stage of pr ocessing, was studied to establish causal factor(s) and effective trea tments. In addition, data on the histology and seasonal prevalence of the disease were obtained. Samples collected soon after slaughter from pelts identified at the pickled pelt stage as having cackle, had a su perficial dermatitis with infiltration of eosinophils. This may repres ent an immediate hypersensitivity reaction of the sheep to lice. Treat ments of sheep with either insecticides, disinfectants or shearing sho wed that where biting lice (Bovicola avis) were removed, cackle lesion s had either disappeared or regressed on pickled pelts. In Trial 1 dia zinon reduced cackle prevalence and severity substantially; cypermethr in had a less pronounced effect. In Trial 2 diazinon, cypermethrin, Hi bitane(R) and Savlon(R) were equally effective in reducing biting lous e numbers as shown by counts oflice at 35 and 63 days post-treatment. Reduction of cockle on pelts from sheep slaughtered at 39 days post-tr eatment was achieved best by both diazinon and shearing. Examination o f other pelts at 67 days post-treatment showed diazinon and Hibitane t o be equally effective in reducing cackle. Furthermore, shearing in th e absence of insecticides reduced the severity and extent of lesions o n cackled pelts. The diazinon excipient and zinc sulphate were consist ently poor at removing lice and reducing cackle prevalence and severit y. The results have important implications for the leather industry in that shearing and good dipping practice with appropriate chemicals at the right time can lead to improved pelt quality. However, an incenti ve scheme for farmers, and a means of identifying individual pelts to the farms or origin, are both necessary before a marked improvement is likely to occur.-