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South Australia worms, flies and lice update - September 2018

SA WormBoss Worm Control Programs

SA WormBoss Drench Decision Guides





Adelaide: Colin Trengove, Sheep Health Lecturer (UA Roseworthy campus) (

The season has barely limped into spring for many in South Australia with at most, modest rainfall to keep the pastures/crops growing—the exception being some southern coastal areas and the south east. Fingers crossed rain will continue a long way into spring.

Worms pay little attention to seasonal conditions and recent monitoring indicates significant worm burdens in ewes and lambs around the state. However, the variability highlights the need to check individual mobs. The standard recommendation that lambs be drenched at weaning still applies with recent pre-weaning monitoring showing typical low counts in ewes and high counts in their lambs.

The adverse seasonal conditions have led to the exceptional circumstance of lambs being weaned into confinement–feeding on grain in some areas. Deaths associated with this management strategy are usually due to lamb failure to adjust to the grain ration rather than parasites, although Coccidiosis and Mycoplasma infections can also cause problems, especially for lambs under stress. It is important to have deaths investigated by a veterinarian as different treatments are required depending on the specific cause. Another issue can be shy feeders and regular checking and removal of lambs failing to adapt to grain is critical for their survival—and especially at their current value. These lambs need to be given preferential attention as even modest weight gain post–weaning is essential to prevent mortalities.

Weaning at 12–14 weeks is even more relevant when paddock feed is limiting as lambs need access to the best feed while ewes will happily regain condition once the need to support lambs is finished. Follow up vaccination plus/minus trace elements may also be required.

The next consideration is whether the ewes and weaners will need a drench before summer.

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