Liver fluke problematic parasite for cattle farmers
Liver fluke continues to be a problematic parasite for cattle farmers. Once confined to wetter areas of the country, cattle movements and a trend towards warmer, wetter winters has resulted in the liver fluke parasite being found across the UK.
The impact of the liver fluke is not always visible, but the sub clinical effects of a fluke burden can significantly affect productivity, resulting in losses.
Slower growth rates, reduced daily liveweight gain, extended finishing times and in the case of breeding herds, impaired fertility, can all be costly.
The presence of even 10 liver fluke has shown to increase time to slaughter by up to 10 days1, and affected animals produce lighter, poorer quality carcasses than cattle with no evidence of fluke infection1.
All of these factors, plus the cost of livers that are condemned due to fluke damage, will reduce profitability of individual animals and the herd as a whole.
Housing cattle over the winter prevents them from picking up any new fluke infections from pasture. Treating for liver fluke at the point of housing will ensure that cattle benefit immediately from the production improvements associated with fluke control. Implementing a housing treatment strategy that ensures cattle are turned out free of fluke at the start of the next grazing season will reduce the infection risk the following year.
A single treatment at housing may not be sufficient to remove all liver fluke present in an animal and protect its productive capability throughout winter. In cattle, production loss can be caused by all ages of liver fluke, but it is the adult stages that have the greatest effect, reducing feed intake by up to 15%2 even where burdens are low.
Different treatments are effective against different stages of the liver fluke. For example, triclabendazole given as a drench is effective against fluke from early after initial infection or from six weeks post infection when applied as a pour-on. Nitroxynil (Trodax®) and closantel are effective from approximately 6-8 weeks post infection, while clorsulon (in Ivomec® Super), oxyclozanide, and albendazole are effective from 10-12 weeks post-infection.
Cattle may be infected with a mixed population of fluke, including varying ages and strains, which may also include a mixture of triclabendazole-susceptible and resistant strains.
The choice of treatment for liver fluke at housing should take into account the population of fluke that are present, but practical considerations such as route of administration and meat withhold times will often also play a role.
The choice of flukicide treatment is also complicated by reports of emerging resistance to triclabendazole. This is the only flukicide which treats the early immature stage of liver fluke, which causes acute disease in sheep but does not typically cause disease in cattle.
Prescribing an alternative to triclabendazole for cattle at housing will reduce selection for resistance and, by targeting the later stages of the parasite, control the impact of liver fluke on productivity.
In order to ensure that fluke control is sustained for the entire housing period and animals are turned out fluke-free in the Spring, cattle should either be tested and retreated if necessary or retreated strategically during housing. The timing of this test will depend on the product used and your vet or animal health advisor will be able to help determine this and to decide on the best test to use.
The wet weather experienced from late summer through early autumn 2019 provided ideal conditions for the fluke’s intermediate host, the mud snail. In areas with mild winters, the fluke may continue to develop into the infective stage, meaning out-wintered cattle may be at higher risk of fluke infection. A late winter dose may therefore be needed, according to local conditions.
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