A MLA funded Producer Demonstration Site (PDS) trial in Western Victoria demonstrated a new method of reducing drench costs and drench resistance in adult ewes.
A worm drenching decision program (targeted drenching - TD) designed to reduce drenching levels in adult ewe flocks at strategic intervals, without incurring significant production loss was applied on 7 properties in South–West Victoria. Expected benefits include significant delays in development of drench resistance and savings in drench costs.
Targeted Drenching uses the average flock worm egg count (WEC) to calculate a proportion of the flock to be drenched to reduce WEC below a critical level compatible with acceptable worm control, rather than to zero. The number to be drenched is calculated after provision for drenching all scouring or obviously thin ewes. Ewes to be drenched are then allocated from the lowest body condition score upwards.
Average drench reductions of 58% and 48% were achieved in 2010-2011 and 2011-2012 respectively without identified production penalties. Summer drenching was reduced by 63% and 49% respectively. The second summer drench averaged across both seasons was reduced by 66%.
Producers either had or rapidly developed the skills required to implement TD on their properties.