Challenges with Parasite Resistance
New Zealand’s livestock industry is facing challenges with parasite resistance, particularly concerning the supply of effective drenches. Wormwise Programme Manager Ginny Dodunski highlights the ongoing issue of triple-drench resistant parasites affecting lambs.
Last autumn, there were instances of lambs suffering from these resistant parasites, with limited treatment options available. This issue is not confined to sheep; dairy support blocks and dairy beef-rearing properties are also experiencing similar challenges.
Drench Supply Constraints
The supply of ‘novel’ drenches, namely Zolvix and Startect, is expected to remain limited this season, as was the case in 2022. Zolvix, containing Monepantel, and Startect, containing Derquantel, have been used for about 12 years.
These trenches are typically reserved for special treatments, such as quarantine and knockout drenching, or on farms where combination resistance is diagnosed. Zolvix is approved for use in both sheep and cattle, while Startect is registered only for sheep.
Manufacturers Elanco (Zolvix) and Zoetis (Startect) have advised that due to manufacturing constraints, they are unlikely to meet the market demand in New Zealand this autumn. The active ingredients in these products are produced in manufacturing plants with limited capacity, leading to supply issues.
Advice for Farmers
Dodunski advises farmers to plan ahead and monitor the effectiveness of their routine drenches. She recommends collecting faecal samples from lambs or calves post-drenching (7 to 10 days for lambs, 14 days for calves) to check for the presence of eggs, indicating the drench’s effectiveness. Testing can be done through local vet clinics, FecPak, or private providers.
If eggs are present post-drenching, farmers should consider their options in terms of drench selection and managing young stock numbers, feeding, and rotational strategies to reduce worm challenges. It’s also important to ensure that breeding stocks are well-prepared for dry conditions.
Wormwise Initiative
Wormwise is a collaborative effort funded and run by Beef + Lamb New Zealand, with input from the NZVA, APHANZ, DairyNZ, and MPI. This initiative aims to provide farmers with tools and skills to combat parasite resistance on their properties.
The issue of parasite resistance in New Zealand’s livestock is a pressing concern, with limited availability of effective drenches like Zolvix and Startect. Farmers are encouraged to actively monitor and manage their drenching strategies to prevent the spread of resistant parasites.
