Routine testing of cattle dung for roundworm eggs throughout the summer has led to less use of wormers, reducing cost and the stress and effort of rounding up first season grazers, on three cattle farms near Preston in the North West of England.
All three farmers, clients of vet Rob Howe of LLM Farm Vets Lancashire, are taking part in a project which examines past anthelmintic use and sets out a new plan centred around testing before treating.
“Most current control strategies rely on the use of wormers applied to entire groups of animals at pre-determined times of the year,” Mr Howe, who is also a member of the Control of Worms Sustainably (COWS) group, explains. “On many farms the same products have been used at the same time every year, for more than a decade. But some of my clients have now taken a different approach and many are surprised they have not actually had to treat.”
Mr Howe advocates a three-pronged approach. This includes vaccinating against lung worm just before turnout and monitoring roundworm levels by taking faecal egg counts during the grazing season. Animals are only treated if results show high levels.
Finally at housing, testing for liver fluke antigen in the dung can quickly and simply alert farmers to the risk level, as can antibody detection tests in blood or milk samples.
Where faecal egg counts for roundworms remain high over summer, a housing dose of a macrocyclic lactone would go some way to prevent a possible outbreak of Type II ostertagiosis late in winter. It would also clear out any lungworms, reducing the risk of pasture contamination next spring.
Testing for roundworms
LLM vet technicians, who were often visiting clients’ farms to do routine vet tasks such as disbudding and fly control, took muck samples from groups of ten animals when they were out in the fields. This was done monthly and then every three weeks from the end of May on participating farms.
They also noted down body condition and the field name. This means future grazing plans could be drawn up so that first season grazers can avoid the worst affected fields. The samples were taken back and analysed for roundworms by the vet team in-house.
“It takes about half an hour to collect the poo samples,” says LLM vet technician Emily Hallet. “If the animals are lying down when you arrive it is easy, because they dung when they stand up. If the results come back as zero or low – there is no need for farmers to worm.”
Derek and Robert Haworth run 90 Ayrshire dairy cows on their 50-hectare Rose Farm, Poulton-Le-Fylde in Lancashire. For 20 years, they had always administered a first grazer bolus at the start of the season to their heifers, which released seven doses of wormer at three-week intervals. Five years ago they changed to giving an injectable solution of moxidectin in each animals’ ear – but liked the sound of testing before treating after talking to Mr Howe.
“We don’t weigh our heifers when they are out so cannot gauge precisely how well they are growing,” says Derek Haworth. “The vet techs came to take dung samples throughout the season and the results came back between zero and 80 eggs per milligram at the highest.
“We were watching the cattle closely when the number went up, but there were never any clinical signs, so we didn’t treat at all this summer. This was better on our pockets, there was less effort and stress on the animals and better for the land and the dung beetles living here. From now on we will keep a watching brief before treating for roundworms.”
Alistair Knowles milks 230 Holstein cross dairy cows at Higher Park Farm, near Preston and had dosed his youngstock routinely three times during their first grazing season with an ivermectin-type product for many years. When samples taken by the LLM vet techs came back showing no sign of roundworm eggs this year, Mr Knowles did not treat them.
“I was really surprised when the vet techs said they didn’t find any eggs in the samples,” says Mr Knowles. “The product I had always used was cheap and I thought it was doing a good job. But in fact it was a waste, as there were never any roundworms there to kill.
Part-time farmer Tom Richardson of Sturzaker House Farm, near Preston has 30 beef shorthorn suckler cows which calve in March.
“We were worming the first season grazing heifers every eight weeks during the summer – but we were doing that based on no actual evidence,” says Mr Richardson. “We used a cheap pour-on wormer and didn’t really think about it.
“While I am working away from the farm, it is very useful to have the vet techs coming here as they are a second pair of eyes. When the results came back negative for roundworms, we stopped treating. I am very keen on dung beetles and other fauna and have sown some herbal leys and I am trying to be more regenerative in my approach. Taking out unnecessary treatments that will harm other creatures, is a good thing for biodiversity.”
Emily Hallett is pleased with how the farmers have reacted to the project so far.
“Last year was the first time we started to talk to farmers about their worming strategies,” she says. “ We were pleased with how many stopped treating for roundworms once tests showed it wasn’t necessary at that time.”
“We have some clients with very large herds who have now not wormed for two summers because the results showed no need. But we have done blood pepsinogen tests with some of them before housing to check there hasn’t been a build-up of roundworms that could cause Type II ostertagiosis in late winter. But so far, the results have come back negative.”