Internal parasites (worms) can affect sheep production by competing with the host for nourishment at all times of the year, depriving host of essential protein.
Immunity and resilience should play a bigger role than the drench itself. This is brought about by understanding what a good balanced diet should be and what nutrition is available to the animal at differing times of year. This is particularly important for lifetime breeders or younger ewes coming along. Measurement is the key component, both of animal and feed.
Strategic drenching should be just that…strategic! Summer drenching is a term that is broadly used, and often abused. It can vary greatly from region to region, year to year and even be very farm-specific.
Factors that influence this are also many and varied, including rainfall, stocking rate, time of peak spring feed to dry off, time of weaning, time of joining, monitoring farm specific worm egg counts (WECs), availability of stubble or break crops and use of confinement feeding.
The important take home message is to keep next year’s lambing paddocks in mind from weaning time onward. These are the future paddocks you don't want to have high burdens of worms in, especially with an autumn lambing, but also at any time for that matter.
Effective drenches are used to hit the “reset” button – that is, to clean the sheep out, but more importantly to protect the build-up of contamination on pastures that will be a future problem. Use of multiple active drenches or some of the “newer” molecules are recommended. Once the drench of choice is established and used, perform a drench resistance check by doing a WEC at day 10 post drenching to be sure that drench has been effective and see of any resistance issues are arising. Full drench resistance testing is more involved, but highly advocated.
For more information or to organise a worm egg count for your sheep, please contact your local Elders branch or call your Elders Livestock Production Specialist.