Improved Design and Use of Shower and Plunge Dipping Equipment for the Eradication of Sheep Body Lice (Bovicola ovis)

Considerable evidence was available indicating that wet dipping practices were failing to eradicate lice on sheep and that ineffective wetting was believed to be a major contributory factor. To examine wetting of sheep in plunge and shower dips, a series of experiments were undertaken to investigate both the mechanical and management opportunities which might improve the efficiency and efficacy of wet dipping of sheep for the eradication of the sheep body louse Bovicola ovis. Results indicated that significant improvements could be made to both shower and plunge dipping equipment and practices which would enhance the likelihood of eradication of sheep body lice. On shower dips there was no significant difference between modified nozzle arrangements and the existing Buzacott® single slot arrangement provided the pump pressure was maintained at >390 kPa at a flow rate >18 l/s (nozzle pressure >230 kPa). Pipe diameter had a substantial effect on pressure losses. Wetting of sheep was significantly affected by their position. Wetting of the sheep in a plunge dip was significantly improved by fully immersing the sheep twice during the course of their swim. Swim length was also significant. The work has also identified a number of issues associated with pesticide residues in raw wool, concerns over pesticide concentrations in the dip wash and a number of occupational health and safety issues. Email: [email protected]