Using wormers correctly will help stop resistance

A SERIES of meetings organised by DairyCo and Eblex have been reinforcing their joint initiative – control of worms sustainably (COWS). Angela Calvert reports from one of the meetings, which was held in Leicestershire.
Farmers should be questioning how they use their wormers; are they using them correctly and effectively, and are they always needed.
So says Alan Murphy, veterinary investigation office with the VLA, Sutton Bonnington.
He said wormers currently available do a very good job in controlling the problem, if used responsibly.
However, with the EU already looking closely at the use of antimicrobials in livestock he added it was likely they would turn their attention to anthelmintics in the future.
This, coupled with the fact no companies are investing in the development of new worming products, means it is vital farmers ensure wormers currently on the market remain available and anthelmintic resistance does not develop, as is becoming the case with sheep.
Every farm is different said Mr Murphy, so farmers need to look at their own situation and know what they are dealing with.
Rather than routine treatment, he advised using faecal egg counts (FEC) to establish the extent and type of problem on farm. This could be cost effective as it may prove worming is not needed.
FECs give a guide to the level of infection in a herd, but several samples are needed to get an accurate picture.
Further investigation by blood sampling may be needed if worms/larvae are not active at the time of FECs, but this should be discussed with a vet or advisor.
He advised farmers to develop a strategy which works for their own farm, based on the knowledge of parasites on the holding, and it should be adapted to any change in management.

Under dosing

Although anthelmintic resistance in cattle is relatively low it develops on some farms, he said, mainly as a result of treatment failure with the biggest cause being under dosing.
This is usually because bodyweight is underestimated, poor maintenance of equipment, poor treatment techniques and failure to follow manufacturers’ instructions. “Dose only when needed,” said Mr Murphy.
“Dosing of adult cows is not normally required, indoor calves are usually worm-free at turnout and use strategic preventative treatments if pasture infectivity is considered high.
“Chose the right wormer – use narrow spectrum products when possible and rotate products where appropriate.
“Reduce dependence on wormers by managing grazing – alternate cattle and sheep grazing, provide low-risk pasture at the start of the grazing season and move mid-season to low-risk pastures, such as aftermaths and make use of new leys.”
Mr Murphy stressed worms and liver fluke are two very different parasites and should be treated separately, saying he was not in favour of combination products.


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