The Sustainable Control of Parasites in Sheep (SCOPS) group has said that it will now provide a nematodirus forecast that will “prove to be an invaluable resource for producers, vets and advisers”.

The nematodirus forecast is an interactive map, updated daily using data from 140 weather stations, SCOPS said. Farmers, vets and advisers can select their nearest or most representative weather station and use the traffic light warning system to quickly check the level of risk.

The forecast also provides advice on treatment options and possible management actions.

Independent sheep consultant Lesley Stubbings said nematodirus battus, the parasite that causes nematodirus, can cause many difficulties for farmers.

“Nematodirus battus…is a tricky one for sheep farmers, as it has a different lifecycle to other worms,” she said.

“Eggs overwinter on ground grazed by sheep the previous year and hatch the following spring once the weather exceeds 10°.

“Over the last few years, the SCOPS forecast has become a key source of information, with many farmers, vets and advisers checking it on a regular basis.”

Risk assessment

Stubbings warned that farmers should be clued in and aware of the conditions and temperatures in their areas to be prepared for the risk posed by nematodirus.

“While the news is full of predictions of the coldest March on record, some parts of southern England have been experiencing sunny spells ideal for nematodirus to hatch and early born lambs could already be at risk,” she said.

“It is really important that sheep farmers know what is happening in their area. If we do get a very cold March followed by a sudden warm spell, lambs that are starting to eat significant amounts of grass (at about six weeks of age) are at high risk.

“This can happen very quickly, causing high numbers of mortalities and stunting the growth of lambs that do survive.”

As well as using the forecast, the SCOPS group advises sheep farmers to monitor for signs of diarrhoea and ill thrift in lambs, and not to exclude nematodirus as a cause of disease even if their regional hatching risk is still low.
“The forecast highlights the level of risk based on local weather conditions – but the exact date of hatching can be influenced by variations in microclimate,” Stubbings said.

“Sheep farmers and their advisers must also take into account 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 every 100m increase in altitude between the farm and the weather station on the forecast map will delay hatching by about seven days.

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