To drench or not at lamb marking

Routine drenching of lambs at marking time may not be in your best interests. Photo by Deb Maxwell.
Routine drenching of lambs at marking time may not be in your best interests. Photo by Deb Maxwell.

Lamb marking time is near. Should your lambs be drenched? Not routinely.

I’ll be presenting the reasons for this at the WormBoss Workshop near Deepwater on Wednesday, November 1 as well as the strategies to reduce your drenching while having fewer worm flare ups.

Some producers will be well ahead of worms, having prepared low worm-risk lambing paddocks and drenched their ewes into those paddocks with an effective short-acting drench. This will have reduced the chance they will need to drench at lamb marking, with some going all the way to weaning before the first drench.

But as conditions vary with season and quality of preparation, we advise producers to always do a WormTest and larval culture on the ewes (not the lambs) 7–10 days before marking to assess the situation. If the ewes need drenching, then also drench the lambs. Test again mid-way to weaning, and then routinely drench all lambs at weaning.

When your results are back just look up the WormBoss Drench Decision Guide on the WormBoss website to see if a drench is warranted. Some producers may only need to drench if their count is 1200 epg (eggs per gram) or more, but for others, a count of 300 epg may be a trigger to drench.

WormBoss advises producers to do a WormTest on the ewes 7-10 days before marking. Photo by Deb Maxwell.

WormBoss advises producers to do a WormTest on the ewes 7-10 days before marking. Photo by Deb Maxwell.

The threshold worm egg count for drenching varies with three key factors: what proportion of each worm species is present (scour worms are drenched at lower egg counts than barber’s pole worm), the condition of the sheep and the condition of the pastures.

What’s the pasture got to do with it you might ask? Good nutrition plays a critical role in the sheep’s immune response. When sheep are in good condition and on good feed they can handle much higher worm burdens before a drench is indicated. Drenching before it is needed can also increase the development of drench resistance.

To attend the Deepwater WormBoss workshop of November 1 RSVP by October 27 to deb@paraboss.com.au or phone 0437 524 163. More information is available at www.wormboss.com.au.