The unseasonal high temperatures in February means earlier-born lambs are at risk from nematodirus, warns the Sustainable Control of Parasites in Sheep (SCOPS) group.
Farmers can view risk in their area using the SCOPS nematodirus forecasting tool at www.scops.org.uk/nematodirus.
Many locations are already highlighted at moderate risk, warns SCOPS, and a confirmed case of disease reported in January-born lambs in Cheshire means farmers need to be on high alert.
Lesley Stubbings of SCOPS says: “Nematodirus eggs look set to hatch much earlier than last year amid recent record-breaking temperatures in February.
“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.
The forecast map is updated daily using data from more than 140 weather stations around the UK, tracking changes in risk throughout the spring and early summer.
Last year it showed the ‘beast from the east’ delayed the annual hatch which meant the threat to lambs in most areas was also pushed back, a stark contrast to this year’s situation.
Hannah Vineer of Liverpool University was involved in developing the online tool. She 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, 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.”