A sustainable approach to worm control in lambs can limit selection pressure for anthelmintic resistance.
Warm and wet weather conditions can cause rapid development and release of worm larvae onto pasture, according to Sioned Timothy, ruminant technical manager at Merial Animal Health.
She outlines four ways farmers can deal with worms in their lambs while also preserving the efficacy of anthelmintic treatments:
- Aftermaths: use aftermaths to provide weaned lambs with clean grazing in July and August.
- Faecal egg counts and wormer tests: understand your resistance through faecal egg counting and testing wormer efficacy before and after drenching. This will inform product selection.
- Targeted selected treatments: TSTs in lambs can reduce the likelihood of selecting for resistant strains of worms. TSTs allow a pool of unselected parasites to pass out eggs onto pasture helping to maintain wormer efficiency.
- Regular weighing: weigh lambs every three to four weeks and monitor body condition to help TSTs. Lambs in good condition and growing well can be left unwormed – in general, 40-60% of lambs require worming.