Sheep producers must act now to mitigate against fluke levels and avoid losses this lambing season, animal health experts are warning.
Scotland’s Rural University College (SRUC) figures reveal acute and chronic fasciolosis prevalence reached a record high in 2012.
Experts are blaming the wet and mild weather conditions, which have provided perfect breeding conditions for the parasite.
Heather Stevenson, SRUC veterinary investigation officer, says post-mortem examinations revealed a tenfold increase in the number of confirmed fluke cases in November.
She warns it is the “tip of the iceberg” and is urging producers with infected flocks to take steps to reduce liver fluke and prevent mortality.
Some flocks are reporting losses of more than 50%. In mid Wales, one sheep producer, who wished to remain anonymous, told Farmers Weekly he had lost 70% of his flock.
Out of a total of 395 breeding ewes and lambs he only has 120 surviving animals.
Early post-mortem results, first carried out in September, showed dead animals had suffered from acute fluke.
The producer believes he has been the victim of Triclabendazole resistance, after random faeces samples taken at a later date showed unusually high egg counts post treatment.
He is now treating animals with a different product but says the outbreak has already cost him an estimated £60,000.
Ms Stevenson stresses it’s essential to conduct post-dosing faeces samples on 6-10 animals three weeks post treatment to ensure efficacy.
John Vipond, SRUC sheep specialist, warns flocks at highest risk are those with undiagnosed chronic fluke.
“If ewes are close to lambing the stress may be the final straw. You have got to treat now, not last minute, because by then the animal is under a lot of pressure.”
Despite many producers treating their flocks for the parasite, experts say there has been a high rate of re-infection this year due to the heavy weight of the challenge.
Dr Vipond says producers that don’t treat for fluke risk problems at lambing such as lower lamb birthweights, inadequate colostrum intake and potentially higher lamb and ewe mortality.
He advises producers to treat six to eight weeks prior to lambing to give ewes time to recover.
But he highlights there is no “blueprint” and says producers should consult with their vet before treating.
Meanwhile Dr Vipond says flocks that had been affected by liver fluke should consider collecting blood samples four weeks prior to lambing to assess energy levels, with the view of updating diets.
He says producers should also avoid feeding excessive starch intakes to prevent sub-acute acidosis.
“Sub-acute acidosis will put more pressure on the animal so it is best to avoid that, because they will already be fragile.”
Instead he recommends replacing starch with sugar beat pulp or distillery by-products, which he says act as good fibre and energy sources in the run up to lambing.
He says producers with infected flocks might also want to think about feeding earlier to repair liver damage and reduce stress prior to lambing.
“They need plenty of access to trace elements and minerals and good quality feed to recuperate.”
Ms Stevenson says fluke risk this year “hinges” on the weather condition in the coming months.
She predicts more wet weather will spell disaster for many sheep producers. “Farmers won’t be able to cope on top of the fluke problem they have had this year.”
In the meantime she said it was important for producers to check fluke forecasts, which can be found at www.nadis.org.uk