Anthelmintic resistance (AR) is more likely to develop if worm populations are being exposed to the same active ingredients repeatedly. Introducing new active ingredients into an annual protocol will help to minimize the development of AR. On cattle farms this probably means reducing reliance on ivermectin and using white and yellow wormers more often. For example, we could save our ivermectin dose for housing time in pour-on form, given its activity against external parasites and inhibited ostertagia larvae. Opting for other clear wormers is also an option on cattle farms, as research has shown that the likes of moxidectin or doramectin can be effective against ivermectin-resistant worm populations.
On some sheep farms, white wormer resistance has reportedly developed. With this in mind, one strategy is to target nematodirus in lambs with a white wormer in April/May – white wormer-resistant nematodirus populations are rare and the species with documented resistance to white wormers will not be proliferating at this time. Thereafter, farmers could switch to clear and yellow wormers for lambs.
Talk to your vet, licensed merchant or animal health adviser about developing the best rotation specific to your farm.
Anthelmintic resistance (AR) is more likely to develop if worm populations are being exposed to the same active ingredients repeatedly. Introducing new active ingredients into an annual protocol will help to minimize the development of AR. On cattle farms this probably means reducing reliance on ivermectin and using white and yellow wormers more often. For example, we could save our ivermectin dose for housing time in pour-on form, given its activity against external parasites and inhibited ostertagia larvae. Opting for other clear wormers is also an option on cattle farms, as research has shown that the likes of moxidectin or doramectin can be effective against ivermectin-resistant worm populations.
On some sheep farms, white wormer resistance has reportedly developed. With this in mind, one strategy is to target nematodirus in lambs with a white wormer in April/May – white wormer-resistant nematodirus populations are rare and the species with documented resistance to white wormers will not be proliferating at this time. Thereafter, farmers could switch to clear and yellow wormers for lambs.
Talk to your vet, SQP or animal health adviser abpout developing the best rotation specific to your farm.
