Experts are advising farmers to monitor for liver fluke and consider treating cattle 8-10 weeks after turnout, because of the higher risk of infection this spring due to the wet winter.
“The risk of infection following turn-out has been increased by the mild and very wet winter weather we have just experienced,” says Lynda Maris, from Merial Animal Health. “Liver fluke infection can affect growth rates and delay finishing.”
Research by the firm shows that even low levels of infection can depress live weight gain by up to 1.2 kg/week while a separate study by EBLEX estimates that the parasite costs beef farmers £87 a case.
The key focus is giving cattle a dose at housing, but another treatment can help control fluke at grass when administered 8 to 10 weeks after turnout if the housing treatment has been ineffective.
As it typically takes 8-12 weeks from cattle becoming infected at pasture to the stage where fluke are in the liver as egg-laying adults, implementing treatment into spring and summer grazing programmes can help kill adult fluke, reduce egg output and decrease pasture contamination.
“Treating cattle post-turnout can help to break the life cycle of the parasites and reduce chances of infection later in the season,” says Mrs Maris.
“It will remove fluke from the animal and improve liveweight gain from grass.”
Treatment has been proved to give a 31% increase in weight gain over untreated cattle and an 8% increase over those treated only for roundworms.
Before treating, Vet Hilary Jones from Usk Veterinary Centre, Usk, Monmouthshire, recommends taking and testing faecal samples to find out if cattle have a parasite burden.
“Despite the wet weather, further treatment should not be necessary for cattle that have been housed during the winter months and have been treated with an appropriate product during this period. However, success depends on the stage of the parasite in its lifecyle when using adult only products, as it may allow younger fluke to develop throughout the winter.”
It is cattle that have been outwintered which are at higher risk, she adds.
Where farmers suspect there is infection, she recommends testing for infection. This avoids unnecessary treatments and minimises the risk of parasites developing resistance.
Certain fields have more of a problem and the risk depends on weather, soil type and wetness. Therefore, the risk is higher in the north than in drier areas of the UK.
Treatments ideally should kill adult fluke as well as having the advantage of providing protection against roundworms, such as combination endectocide ingredients ivermectin and clorsulon, which can replace wormer-only products. If farmers are looking just to treat fluke then albendezole and oxyclozanide will target the adult stages.
“Farmers should consider contacting their vet or use NADIS for an up to date risk assessment and parasite forecast,” says Mrs Jones.