A new parasite tracking initiative is reporting an increase in exposure to the gutworm ostertagia ostertagi in cattle during the 2020 grazing season – but also indicated that liver fluke exposure is currently low, except for hot spots in Central and South-west Scotland.

Launching the tracker, Boehringer Ingelheim Animal Health's senior brand manager, Victoria Hudson, explained that the data collected from 90 dairy farms in GB, via National Milk Laboratories, was helping track parasite risk and provide more specific guidance to livestock producers.

She said: “Our data is collected from Elisa bulk milk tests from dairy farms, but we expect this information will be of use to all livestock producers due to the prevalence of liver fluke and ostertagia ostertagi across Great Britain. When bulk milk tank antibodies to these parasites become elevated, it provides an indication of regional risk that is relevant to other cattle producers and the liver fluke results will also be relevant to sheep producers.

“We hope when this data is used in combination with parasite forecasts, farm-specific conditions, and herd history, livestock producers, animal health advisors and vets will be able to make better-informed decisions on parasite monitoring and control.”

Data to the end of August, showed that around 80% of tested herds had high levels of ostertagia antibody in a bulk milk sample, indicating high exposure to this worm during the season. “This highlights the potential risk that it may pose to cattle of all ages grazing in all regions of GB,” said Boehringer’s ruminant technical manager, Sioned Timothy.

“Dairy herds that have not treated for worms during the grazing season should consider testing a bulk milk sample. In addition, producers should be mindful that the warm and wet autumn weather will promote ongoing larval activity on the pasture, and could leave youngstock at ongoing risk of parasitic gastroenteritis,” she warned.

It is a different story for liver fluke, where the majority of herds remain classed as negative, with 68% presenting no or very low levels of antibody in a bulk milk sample. However, a small number of herds tested positive, primarily in the westerly areas of Great Britain.

“Dairy farmers in westerly areas of England, Wales and Scotland that haven’t treated herds for liver fluke this year should consider performing a diagnostic test to determine whether chronic fluke infection established in 2019 is impacting on the farm’s productivity,” said Ms Timothy.

“There is some evidence that antibody levels are increasing in these regions. This is most notable in South-west Scotland. Livestock in this area are potentially being exposed to infective fluke on the pasture and as a result, there may be a risk of acute fluke disease in sheep."

Cattle and sheep producers are urged to speak to their vet or animal health advisor for advice on how to monitor and treat liver fluke and ostertagia ostertagi on their farms.

• Maps showing infections levels of Fluke and Ostertagia across England Wales and Scotland. Green = negative/weak, yellow = low, orange = medium, red = high