Guidance updated on controlling worms on farms 20 April 2021 | The guidance will help farms looking to reduce their dependence on wormers The UK's three levy boards have updated their guidance for sheep farmers on controlling worms more effectively in the future. The sheep industry has become more reliant on pastures grazed only by sheep, and as a result, the dependence on wormers has increased. Worm control is vital on any sheep farm, and heavy worm burdens can dramatically decrease lamb growth rates and the profitability of sheep systems. But for worm control to be effective long term it is important to preserve the efficacy of anthelmintics that are used by minimising resistance.