The problem is not the drenching, but how it is done.
Drench resistance is widespread and is a known threat on sheep farms. A 2006 survey2 also diagnosed drench failure on 94% of 62 beef farms in the North Island. Many sheep and beef farms graze young stock that then go back to the dairy platform, taking parasites from the grazing farm with them. If parasites are resistant to the actives in the drench you use, you could be wasting money.
Furthermore, research has found milk production of dairy heifers can be negatively impacted for several lactations if they were affected by parasites as young animals3.
The dairy survey showed many farmers are still drenching their whole herd at dry-off or around calving and are not using or don't know about other parasite management tools for young stock.
If our drenching methods don't change we could see a decline in animal health and productivity. A starting point is to stop routinely drenching all cows in the herd. Adults are immune to parasites, but this comes at a cost. The 'cost' is less if they are in better body condition, are older and aren't stressed due to weather, feed shortage, disease or other reasons.
Not all animals in the herd will be in the same situation. Cows in good condition can handle stress and a parasite incursion better, so these animals should be left untreated. The larger this untreated (refugia) mob is, the greater the protective effect for slowing drench resistance will be.
If an animal needs to be treated, a short-acting clean-out drench may make you feel better but not really benefit the cow. Yes, it can eliminate parasites in the animal, but when grazing grass, cows are ingesting thousands of parasite larvae daily, especially if feed is short.
So when animals are under pressure and facing a larger challenge, use the longer-acting treatments that can keep killing incoming larvae, giving at-risk cows more protection.
Cydectin® Pour-On is one of the few products with a broad spectrum of persistent activity against many worms. It has ongoing activity against the most production-limiting worm (Ostertagia ostertagi) for 35 days, and 28 days for Trichostrongylus axei and several other parasites. It has no withholding periods so can be used on cows before or after calving, with no bobby calf or milk withhold. It is also effective against biting and sucking lice for cows needing a worm and lice treatment.
Using more of the tools to manage parasites is increasingly important, so speak with your local Farm Source TSR, vet or visit wormwise.co.nz for advice on how best to reduce the effects of parasites on your stock and slow the threat of drench resistance on-farm.
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1 2021 Cinta-Zoetis Agribusiness farmer survey.
2 Waghorn T. et al. Prevalence of anthelmintic resistance on 62 beef cattle farms in the North Island of New Zealand. NZVJ 2006.
3 Ploeger H.W. Effect of Naturally Occurring Nematode Infections in the First and Second Grazing Season on the Growth Performance of Second-Year Cattle. Veterinary Parasitology, 1990.
Article supplied by Zoetis New Zealand Limited.