A regional model of sheep lice management practices to examine the impact of managing straying sheep combined with other management choices

A model of lice management systems was used to investigate the potential benefits of improved fencing against straying sheep, used in conjunction with other management options for lice control. The impact of combined strategies was simulated over a 20-year period. Management options included in the model were: lice eradication rate, lice detection, intervention level, improved fencing to reduce straying sheep, and biosecurity of purchased sheep. The modelling found it was cost-effective to improve fences for an initial average cost of $20 000/property if the number of properties from which strays could enter was reduced by ≥40%, but for average Australian properties this represents less than 20% of the boundary replaced. In order for fencing to be a cost-effective part of lice management, the fencing must target sections of boundary fence that will provide the greatest protection from contact with neighbouring flocks. The model showed that improved biosecurity against straying sheep combined well with improved eradication rates. However, biosecurity for purchased sheep may be the most cost-effective option.