The mild, wet winter is set to result in an extremely variable challenge to young lambs, from nematodirus across the country.
Sustainable Control of Parasites in Sheep (SCOPS), as a result, has relaunched its nematodirus forecasting tool, which is said to be a valuable method of checking the risk to lambs.
The nematodirus alert map will go live once again on the SCOPS website from Monday, March 2, showing when hatching of nematodirus eggs is predicted based on local weather conditions.
When are hatches most likely to commence?
The exact date of hatching can be influenced by variation in micro-climate and early cases are also possible from overwintered larvae.
A link on the forecast also gives access to an archive section so vets, advisers and farmers can consult previous forecasts when the risk levels changed in their area.
Hatching has been seen in January in some areas and although the colder conditions in February could slow things down, experts believe a protracted hatch is likely.
This has the potential to catch sheep farmers out, if they are not watching the forecast and assessing the risk to their lambs.
Field-to-field variation
“When deciding whether or not to act, sheep farmers must also take into account variation from field-to-field and farm-to-farm,” says Dr. Hannah Vineer, Liverpool University.
“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 every 100m increase in altitude 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.
“Moving lambs to lower risk grazing that was not grazed by lambs last spring will help to avoid a high challenge,” added Dr. Vineer.
“However, nematodirus eggs were commonly seen in faecal samples from sheep of all ages throughout 2019 which means that even land grazed by older sheep could be contaminated.
Although faecal egg counts cannot be used to decide when to treat young lambs for nematodirus – as the damage is done by larvae that don’t produce eggs – regularly monitoring and recording faecal egg counts can help track which fields provide the safest grazing for lambs come spring.
It is also important to monitor for signs of diarrhoea and ill thrift, and don’t exclude nematodirus as a cause of disease in lambs even if your regional hatching risk is not yet high.
Sheep farmers having had cases of nematodirus confirmed on their farm are requested to help inform the forecasting tool themselves by logging their cases on the website using the first half of their postcode.
