Reducing exposure to liver and rumen fluke

Some 86% of condemned livers, in meat factories, were due to liver fluke, according to a recent trial conducted by University College Dublin’s Dr. Theo de Waal.

Results show, of these livers examined, 97% were already at the adult stage; with only a small percentage in the immature liver fluke stage.

Liver fluke is a parasitic disease caused by a flat worm that affects cattle and sheep. Depending on the degree of infection, it can be associated with economic losses such as reduced meat and milk production.

liver

Fertility in beef cattle can also be reduced when liver or rumen fluke are present, he told a crowd of over 500 farmers at this week’s Teagasc National Beef Conference.

Beef cattle affected by fluke may take an extra 80 days to reach target market weights. Losses can also occur when livers are condemned in meat processing plants.

Heavy burdens of immature rumen fluke can cause disease and sometimes mortality, due to the damage caused to the intestinal wall; mature rumen fluke infections are usually of lesser importance.

Negative impacts on production such as lower milk yields and slower growth rates have been reported.

Both rumen and liver fluke use the mud snail as an immediate host. The mud snail is widely distributed in Ireland. Both the snail and the eggs of these parasites thrive in mild, wet and damp environments – conditions that are present on almost every Irish farm from year-to-year.

Non-chemical control and pasture management

There are many ways farmers can reduce the possibility of exposure to liver and rumen fluke larvae – both by the sustainable use of drugs and non-chemical controls.

According de Waal, identifying the risk of infection is the first step on any farm. Avoiding high-risk pastures, along with keeping cattle and sheep on separate grazing platforms, is key to minimising the risk.

Infection risk is highest in late summer and autumn – early housing must be considered if pastures are wet.

“Abattoir feed back is also a good indication as to the status of the disease present on the farm,” he claimed.

Wet muddy areas need to be either drained or fenced off – these areas are snail habitats. Minimising water areas around troughs and ensuring any leaking pipes are fixed are crucial to ensuring mud snail control.

He said: “Animals that are known to have an infection or have a history of infection should be quarantined and treated appropriately.”

Other measures include fencing off draining ditches, ponds and watercourses, while reducing the stocking rate will limit poaching and thus, reduce the risk of exposure.

Drug treatment

He also claims that different flukicides kill liver fluke at different stages of maturity; so it’s important to know what stage is likely to be present to select the appropriate drug.

“The aim of a treatment programme is to remove liver fluke to prevent damage to the host. It is commonly administered at housing to cattle that have grazed fluke-infected pastures.

By the strategic use of these drugs we can reduce the contamination of the environment and the life cycle of the parasite.

Currently, oxyclozanide (normally marketed as a treatment for liver fluke) is the only drug with proven efficacy against immature and mature rumen fluke infections.

The detection of rumen fluke eggs in faecal samples, or the detection of the adults in the rumen, is not a reason to start specific control measures.

The routine implementation of a preventive dosing regime for rumen fluke is rarely justified – except on farms where severe disease and losses have been confirmed in the past.

According to de Waal, the over-use of any flukicide should be avoided in order to minimise the risk of resistance.

This is especially important in the case of rumen fluke, where the indiscriminate use of a single compound like oxyclozanide over several years can rapidly lead to the development of resistance.

“Resistance of liver fluke to triclabendazole, albendazole and closantel has been reported,” he concluded.

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