News & Advice


Sep 3, 2020 | Dry stock, Grazing youngstock, Sheep

Heifers pre-mating: Pre-mating drenches should be given a few weeks before the planned start of mating to ensure that the heifers are in the best health before the bulls go out. Faecal egg counts and larval cultures are very useful at this point to see what worms are present and to determine the best products to use. This can be a very cost effective test; a pooled sample from 10 to 12 animals from the mob will give a reliable estimate of the worm challenge in the group. Once again any heifers still recovering from facial eczema will benefit from a drench now, and giving Ostertagia protection is a good idea after a stressful winter to avoid potential Type II Ostertagia. Dectomax injection or pour-on works well for this.

Lambs: Lambs born to ewes given long acting drenches pre-lambing (Eweguard, Exodus, Dectomax, Boluses etc) will not usually need drenching at docking.

Exit Drenching of Ewes: Ewes treated with long acting drenches pre-lambing should be drenched with Startect or Matrix at the end of the ‘long action’ period. This aims to help prevent development of drench resistance by eliminating worms not killed by the long acting drench. Due to the variation in duration of action, a faecal egg count now will help you determine know how well your long acting product is working. A pooled sample of 10 to 12 ewes will give us a good idea of the worm burden.

If the ewes have not been given a long acting drench pre-lambing, they should be given a broad spectrum, multi action drench at docking such as Arrest, Switch or Matrix. In general, the lambs are not likely to benefit from a drench this early in life.

The benefit of drenching ewes at docking lies mainly in reducing the output of worm eggs that could infect the lambs as well as providing a direct effect on the ewes’ health and production.

Drenching tips for calf rearers

As with anything there are a few golden rules that everyone should follow to ensure that the job is done right.

  • Never drench calves at the calfeteria or mix drench with milk. Most oral drenches require slow absorption from a rumen depot for effectiveness – adding to milk prevents this happening because sucking milk causes closure of the oesophageal groove, then the milk bypasses the rumen and goes straight to the abomasum or fourth stomach.
  • Oral white and clear drenches are the best for calves (oxfen and levamasole). Calves that are under 120kg cannot have Abamectin drenches. Check the label instructions if you are unsure.
  • Determine if they actually need drenching at all with a faecal egg count and faecal coccidial count.
  • Always check that the drench gun is measuring accurately and that the dose is correct. Weigh enough animals to get an accurate weight. Issues can arise with either underdosing or overdosing. You need to drench to ensure the heaviest animal is accurately dosed. If there is a large weight range in the group then you need to split them and give a heavy and a light dose.
  • Never swap drench containers. If decanting to a smaller drenching container always write on container or transfer back to the original container when finished. Double check the correct product is being used.
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