Research at Teagasc Grange has highlighted potential issues around wormer resistance on Irish livestock farms.

While resistance to all three classes of anthelminthic wormers (white, yellow and clear drenches) has been found recently on sheep farms, the extent of the problem on cattle farms is yet unquantified.

Dr Orla Keane and Teagasc Walsh Fellow Anne Kelleher examined anthelminthic resistance on 16 dairy calf-to-beef farms using the faecal egg count reduction method of sample, dose, sample.

Fenbendazole (white drench, oral) and ivermectin-based (clear drench, injectable) products were tested.

A fully effective anthelminthic dose will reduce egg count to zero. On 16 out of the 16 farms tested, the ivermectin product failed to reduce egg count by more than 95%. The fenbendazole product failed in a similar fashion (<95% kill) on 12 of 16 farms. The other four farms responded to treatment.

Commenting on the results, Dr Keane stressed that the results were preliminary and that validatory lab work was ongoing.

“We’ll be looking for new farms for a follow on next year,” she added.