As we go into April, sheep farmers need to be aware of the risk Nematodirus can pose to their flock. With the weather warming up it, is likely we will see more cases of the disease and it is important producers keep an eye out for lambs dying suddenly and eliminate Nematodirus as a cause.Nematodirus battus is a deadly gutworm and normally affects young lambs between six and 12 weeks of age. Eggs deposited on pasture by lambs the previous year hatch in spring, triggered by a chilling over winter followed by seven days between 11.5°C and 17°C. The risk is higher when there is a cold spell followed by a significant increase in temperature.
Young lambs take in large numbers of larvae as they graze which damages their gut, leading to black scour and death. Where possible, farmers should avoid putting young lambs on paddocks that could have been contaminated with Nematodirus eggs, particularly if they were grazed by ewes with young lambs during the previous grazing season.
The University of Bristol has developed an online tool, available on the SCOPS (Sustainable Control of Parasites in Sheep) website, which provides a Nematodirus risk forecast. The tool predicts when Nematodirus eggs are likely to hatch in an area and therefore when there is a higher risk of a disease outbreak.The tool now uses daily temperature data from 140 weather stations around the country to help give producers more localised and up-to-date information on the Nematodirus risk in your area. The forecast predicts the likely date of hatching and how long larvae will be infective on the pasture. This is incorporated into a Google map so farmers can identify the weather station closest to their farm, which will provide a risk warning for their area and advice on treatment and management actions.
Variation in spring temperatures over the last few years has meant predicting when outbreaks might happen is becoming more and more difficult. This, coupled with the fact faecal egg counts alone are not reliable because damage is done by immature larvae and not egg shedding adults, means farmers need a reliable warning system and this tool can really make a difference.
Producers are also being encouraged to report Nematodirus cases. This will enable mapping of the disease throughout the season and farmers will be able to view whether there has been an outbreak near them. The first outbreak was reported on 17 March and there are currently five confirmed case of Nematodirus already this year.Farmers should treat young lambs to prevent disease when there is a high risk forecast in their area. More than one treatment, at three-week intervals, may be necessary, depending on the spread of ages in the group and whether the high risk forecast is prolonged. You can find more information on the control of worms by taking a look at the Better Returns Programme (BRP) manual Worm control in sheep for Better Returns.
Visit the SCOPS website to find out the risk forecast in your area and to report cases of Nematodirus by completing the survey. Also, in case you missed it, Lesley Stubbings from SCOPS recently presented a teleconference for AHDB Beef & Lamb about worm control in sheep. Click here to listen again.
Remember: Stay vigilant, check the risk forecast in your area, and report cases of a Nematodirus on your farm.