Managing grazing

Because the mud snail is critical to the liver fluke lifecycle , identification and exclusion of snail habitats from livestock offers some measure of control – but is very difficult to do in reality. For example, drainage eliminates the snail and offers an effective means of control, but does not sit well with environmental schemes to protect wetland areas.

Practical options to consider if appropriate for your farm

• Keep stock off the wettest fields in the autumn and the winter, when the incidence of disease is at its highest.
• Fence off high-risk areas, such as drinking areas or streams that can be replaced by water troughs. In dry years, both the snails and livestock concentrate in these areas, which means the risk of infection can be very high.
• Prevent/repair leaks from pipes and water troughs, as leaks can create a perfect habitat for the mud snails, even if only temporary.
• Housing animals to remove them from high-risk pastures is an extreme strategy some farms in high-risk areas have to employ. Feeding well-made silage during this time poses no risk to them, although there is evidence that small numbers of viable liver fluke cysts can be found in poorly made silage (20% dry matter exposed to oxygen for the duration of the ensiling process).
• Get to know your risk areas over time and map them, to help understand options for control and to target the right groups of livestock for diagnostic testing.

This useful guide to mapping your farm for fluke risk is available on page 23 of the Liver fluke control in grazing livestock booklet compiled by the levy bodies.

Another management consideration, in addition to grazing management, is managing the presence/type of fluke on your farm. If you have mud snails on your farm but no fluke, you do not want to introduce the parasite. If you have mud snails and fluke but not treatment-resistant fluke, you do not want to introduce resistant parasites. Therefore, quarantine treatment and management for incoming stock is vital.