Nematodirus battus, keep an eye on the forecast this spring…

February 6, 2024

Nematodirus is a worm that can cause sudden death and significant growth reductions in lambs. It is different to other worms because the larvae survive within the egg on the pasture, allowing infection to pass from one lamb crop to the next year’s lamb crop. This means pasture that had ewes and lambs on in the Spring last year is high risk for Nematodirus this year. Mass egg hatching is triggered by a sudden increase in temperature. If the hatch coincides with the time when lambs are starting to eat grass, lambs may suddenly start dying. Worm egg counts will not be increased because the larval worm can cause significant damage before it develops into an egg-producing adult. This means we need another way of identifying when to take action. SCOPS run a forecast which predicts when the risk of Nematodirus is increased. It is advisable to keep a close eye on the forecast for your region to decide when the risk is high. At this point you may opt to move lambs to a lower risk pasture or use a wormer if moving is not possible. White (1-BZ) drenches are normally highly effective for treating Nematodirus so should be used as the first treatment of spring.

Find the forecast here:

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