Catrin Jones, Tirlan Farm, Brechfa, Carmarthenshire, and four other farms were involved in a three-year European Innovation Partnership (EIP) project in Wales¹. The study looked at the spring rise - a relaxation of immunity in the ewe around the period of lambing, which can lead to increased worm egg production.  

The study found nutritional stress, as measured by a loss in Body Condition Score (BCS), was the key to determining which ewes had the highest Faecal Egg Count (FEC) and when this occurred relative to lambing.  

Renewed Advice  

Previous advice has been to only worm ewes with a low body condition score. However, this study has refined the advice, meaning only ewes losing body condition in the six weeks up to lambing should be targeted.  

Ms Jones, who lambs 400 primarily Beulah Speckled Face ewes from 10 March onwards, would traditionally blanket treat all ewes with a wormer in May.  

However, with support from Independent Sheep Consultant Lesley Stubbings, who was involved in the project, she could target wormer use to only those ewes that needed it, cutting wormer use last year to just 37%. 

Targeting What Ewes to Treat  

Ewes are body condition scored at scanning and then again when given their clostridial vaccine in mid-February. Anything that has lost condition is marked and drenched with the long-acting wormer CYDECTIN 2% LA at lambing.    

CYDECTIN 2% Long-Acting Injection has a worm persistency period of up to 111 days. Its long persistency means it can help reduce the risk of pasture contamination and therefore reduce the need to treat the lambs, saving time, and money and reducing the number of wormer doses on the farm.  

However, its use must be considered carefully to get a balance between preventing anthelmintic resistance and controlling worms.  

Although the data is yet to be analysed, Ms Jones believes the new worming policy has resulted in fewer worm counts in the lambs and treatments.  

"We regularly FEC lambs from six weeks old until they are sold. We think we used less drench in the lambs last year, but we will know once we have analysed the data.  

"Working with Lesley has given me the confidence to move away from blanket treating and only to target those ewes that need it. We must do what we can to reduce wormer resistance," she added.  

Although the project has ended, Ms Jones continues to target wormer use in the same way. She said: "We have already earmarked the ewes losing body condition this year and they will be targeted with CYDECTIN 2% LA at lambing," she said.  

Ms Stubbings said the results from the study have allowed them to target further what ewes need worming and when.  

"Just because you have a low body condition score ewe, it doesn't necessarily mean they are the ones to treat. It's those ewes that are losing condition that are the ones to target," she said.  

"By worming in this way and using a long-acting product, farmers can reduce pasture contamination without blanket treating ewes.  

"It's important farmers understand what is happening in their own flock for sustainable worm control," she added.  

Zoetis Vet Ally Ward urges farmers to embrace the study's new advice and use CYDECTIN 2% LA responsibly. "Work with your animal health advisor and understand what is happening on your farm. One way to do this is by assessing which ewes are under nutritional stress by body condition scoring.  

"By targeting ewes losing body condition when you treat, you are helping to safeguard the product for future use," she added.  

    1.     Stubbings, et. al., 2022. Targeting anthelmintic use in ewes.