Sheep farmers advised to be on high alert for nematodirus

Farmers are advised to be on high alert for nematodirus in lambs as the recent temperature rises have contributed to an increased risk in many parts of the UK.

The Sustainable Control of Parasites in Sheep (Scops) group has advised that the record-breaking temperatures in February could cause nematodirus eggs to hatch earlier than usual.

See also: A guide to effective wormer use

Lesley Stubbings of Scops said: “Locations throughout the UK are already showing a moderate risk on the Scops Nematodirus Forecast map, which means a hatch is likely to take place within seven to 14 days if warm weather persists, putting lambs aged six to 12 weeks of age at the most risk.”

There has already been one confirmed case of nematodirus in January-born lambs  in Cheshire.

Assessing the risk and taking action

Ms Stubbings advises sheep farmers to use the nematodirus forecast map on the Scops website and monitor risk in the local area:

“Find your local weather station and, as soon as it changes colour, carry out a risk assessment to decide whether you need take action for your flock”.

The map can be found on the Scops website.

Hannah Vineer of the University of Liverpool says: “When deciding whether or not to act, it is important to assess the risk to each group of lambs based on the history of the field and its aspect and altitude.

“South-facing fields tend to have an earlier hatch and, as a guide, every 100m increase in altitude will delay hatching by about seven days.

So, for example, if the nearest weather station on the map is at 200m above sea level and the farm 100m above sea level, hatching could be around seven days earlier than our forecast.”

Risk assessment

If your lambs are grazing pasture that carried lambs last spring and you answer yes to one or more of these questions, your lambs are at risk.

  • Are they old enough to be eating significant amounts of grass? (Generally six to 12 weeks of age but may be younger if ewes are not milking well.)
  • Do you have groups where there is also likely to be a challenge from coccidiosis? For example, mixed-aged lambs are a higher risk.
  • Has there been a sudden cold snap recently followed by a period of warm weather?
  • Have you got lambs that are under other stresses – for example, triplets, fostered on young or older ewes.

Source: Scops

If you cannot avoid high-risk pasture grazed by lambs the previous spring and decide you need to treat for nematodirus, Scops advises farmers to use a white (1-BZ) drench. 

If treatment is required, effective use of wormer is all about administering the right product, at the right time, at the right dose and with the right technique.