Sheep farmers are being urged to conduct regular faecal egg counts, as data reveals there is no such thing as a ‘regular worm season’.
Data from 25 farms across the UK that regularly monitor faecal worm egg counts (FWEC) in lambs as part of the Zoetis Parasite Watch Scheme showed unexpectedly high strongyle (roundworm) burdens as late as autumn last year.
Egg counts began rising in May, peaking in August when the highest average count of almost 600 eggs per gram (EPG) was recorded. Counts dipped in mid- to the late season before rising again to 650 EPG in November.
Zoetis vet, Patricia van Veen said: “This is different to previous years when egg counts typically stayed high during summer and fell during the autumn as the weather turned colder.
“It highlights the importance of conducting regular faecal egg count tests for monitoring and drench efficacy to prevent unnecessary lamb losses.”
Independent sheep consultant Nerys Wright echoed this sentiment: “This clearly shows there is no such thing as a regular worm season due to changing weather patterns.
“I would encourage farmers to remain alert to the risk of parasites later in the season and continue to monitor egg counts to ensure we are treating when it is needed.”
She advised farmers to start monitoring worm burdens when lambs eat enough grass and likely begin to ingest worm larvae – around six weeks-of-age.
She added egg counts should be monitored every three weeks, with 10-15 dung samples taken from each group of lambs.
“Samples should be taken from a representative number of lambs in the group. Samples should be collected when fresh, ideally still warm to the touch.
“If samples cannot be sent to the lab immediately, they must be stored airtight in a fridge to prevent them from heating and worm eggs from hatching,” she warned.
FWEC over 400-500 EPG can indicate a high challenge, although some lambs can better withstand worm challenges according to the sheep consultant.
Alongside FWEC, the monitoring of lamb growth rates and ewe body condition scores can serve as useful indicators of strongyle infection.
Wright has advised farmers to work with their vet to create or update a parasite control plan tailored to their farm, including using a mid- to late ‘break dose’ of group four and group five wormers to help manage anthelmintic resistance and prolong the efficacy of all other wormer groups.
“Regular faecal egg counting in sheep will help you build a picture of what’s happening on your farm and help preserve the efficacy of all wormers,” she said.
Now in its 10th year, farmers, SQPs/RAMAs and vets can use Parasite Watch, the UK’s most comprehensive parasite tracking service, for free and sign up to receive alerts.
