29 July 2025
The use of wormer in a Welsh sheep flock has reduced significantly thanks to targeted selective treatment (TST), a process that identifies which lambs need worming and avoids blanket dosing.
TST uses specific individual markers, such as growth rate, and considers the flock’s faecal egg count (FEC).
Father and son Glyn and Chris Davies, who run a flock of 650 crossbred ewes at Awel y Grug, Cefn Coch, Montgomeryshire, have been trialling this approach as one of their Farming Connect Our Farms projects, and the results have been very positive.
In July, when high temperatures and rainfall resulted in an FEC of 446 eggs per gram (epg), they would ordinarily have treated all lambs.
But by sticking to the TST policy, less than 50% of the lambs actually needed dosing, says Owain Pugh, Farming Connect red meat sector officer for mid Wales, who is supporting them with their Our Farms projects.
“Following a TST strategy has so far resulted in 855 fewer doses administered over the course of two treatment cycles, one in June and another in July, and a saving of close to £60 in drench,’’ says Owain.
“It’s a good financial saving on top of the massive benefit of reducing anthelmintic resistance developing and protecting dung beetles.’’
It is a further step in the programme the Davies’ have in place around responsible anthelmintic use, a journey they started when Chris first became a member of Farming Connect discussion groups in 2018.
Initially, a FEC reduction test was carried out to establish the efficacy of white drench (1-BZ); this revealed worm resistance to that anthelmintic group which may have developed from over-reliance on a single drench group.
Going forward, the Davies’ were advised by their veterinary practice, Hafren Vets, to only use white drench to treat for Nematodirus when strongyle worm burdens were low.
For the rest of the season, they rotate yellow (2-LV) and clear (3-ML) drenches and use orange (4-AD) and purple (5-SI) strategically to avoid resistance to those groups.
They invested in an auto-calibrated dosing applicator which connects to their weigh scales and allows them to adjust dose according to lamb weight.
There were technical challenges in setting this up but with support from livestock advisor Matt Blyth, facilitated by Farming Connect, this was resolved; they invested in a specific weigh head which was compatible with the Cotter Agri Smart worm app used for TST.
Fiona Kenyon, Principal Research Scientist at the Moredun Research Institute, analysed the FEC samples to establish which worm species were present.
This is valuable information that helps to understand which worm species are developing wormer resistance, she says.
“It will allow us to optimise when specific drug classes are most effective,’’ she says.
TST, says Fiona, offers potential to save time, labour and cut drench use, all of which reduces input costs.
“It’s fantastic to see that the TST approach is working so well for the Davies family.
“TST has the added benefit of slowing the development of wormer resistance, helping our limited wormers remain effective for longer.
Using our wormers in a sustainable manner is of critical importance and this project shows that it can be done without affecting animal productivity and saving time and money.’’
For Glyn and Chris, the project has been transformative.
Not only have dosing periods speeded up considerably – one session took them only 30 minutes, three times quicker than treating the entire group – but they have made cost savings and, importantly, worms aren’t building up immunity to drenches.
Chris says establishing the exact weight of each lamb and administering a corresponding dose makes sense in multiple ways.
He now realises that guessing the weight of an animal by visual assessment, as he did in the past, is unreliable. “With TST we are not under or over dosing,’’ he says.
By monitoring weights more closely, the business has been able to capture higher lamb prices.
“When I can see lambs are consistently gaining weight, and rotational grazing is helping with that, I can hold off from selling them for a few weeks to allow them to gain more weight,’’ he says. “In the past I would have been aiming to sell them as quickly as possible.’’
Chris admits that setting the system up was challenging and he needed Matt’s support with that. “I can see why farmers might give up at that stage but once everything is up and running, they won’t look back.’’
TST and other project work he has been involved in through the Our Farms network, including growing clover for finishing lambs and rotational grazing, has transformed the business, he adds.
“All the changes we have made in the last two years have put us in a much stronger position.’’