Zoetis is warning all farmers to take regular faecal egg count tests to help prevent unnecessary losses, as data shows that the risk period changes yearly.
The animal health company said results from the 25 monitoring farms in its parasite watch scheme found that peak faecal worm egg counts in 2023 occurred between June and October.
The highest average count was in September and was almost 600 eggs per gram (epg). The suggested threshold for considering treatment is 250 epg.
This is compared to 2019, when the risk period started in early March and ran through until the autumn, with moderate levels throughout the season, Zoetis said.
Now in its ninth year, the data from parasite watch shows that no two years are the same.
Zoetis said this means farmers should monitor their lambs for gastrointestinal parasites throughout the grazing season, to ensure they are being treated only when needed.
Zoetis vet Patricia van Veen said: “The Zoetis Parasite Watch data is based on actual FWEC in lambs on 25 farms throughout the UK, updated most weeks throughout the grazing season and can be used to help assess the risk of disease and production losses associated with high worm burdens.
“The only way farmers can truly understand what is happening in their flock and time treatments appropriately is to regularly monitor faecal egg counts, lamb growth rates, and body condition.”
Nematodirus
Data is also available for gastrointestinal parasite disease Nematodirus, that often occurs before eggs appear in the faeces.
Parasite watch data for Nematodirus from the previous year alongside the SCOPS Nematodirus forecast data can be used to highlight the real-time risk, enabling targeted treatment, Zoetis said.
Devon sheep farmer Peter Baber has been monitoring faecal worm egg counts in his flock for over 30 years and breeding worm-resistant sheep in his flock of 900 ewes, which consist of Exlana, Suffolks, SufTex, and Texels.
Baber said it is difficult to predict when worms will pose an issue.
“You have to monitor worms to be able to manage them responsibly. That means keeping an eye on stock condition and performance as well as regularly taking faecal egg counts,” he said.
“Once we have made our breeding selection, there are very few situations when we need to drench everything in the flock.
“Most times, we can selectively treat groups of animals depending on the severity of the infection.”
Baber said monitoring is vital, and that it “makes no sense” to drench any sheep without checking to see if they really need it.
“We’ve got the technology; it is really simple to do and it is so important that it is used,” he said.
