Wet spring weather may lead to worm larvae being released onto pastures increasing the risk of productivity-limiting parasite burdens in sheep this summer. While in cattle, lungworm infection will pose a threat to unvaccinated and naïve young stock and adults from July onwards.

Ewes, grazing on heavily infected pastures, and treated with a short-acting wormer at turnout may require further worming treatments to limit pasture contamination during the ‘peri-parturient rise’ (PPR). Ewes treated with a persistent anthelmintic before turnout should not require further treatment.

Sioned Timothy, ruminant technical manager at Boehringer Ingelheim, said: “It’s important to take a sustainable approach to worm control in lambs to limit selection pressure for anthelmintic resistance. However, with the right approach, worms can be controlled effectively and growth rates preserved.

“Moving weaned lambs onto aftermaths during July and August can reduce the risk of parasitic disease. This simple management practice reduces exposure to the high larval challenge that can build up on pasture. This is one of the most critical components of sustainable parasite control.”

Ms Timothy said that lambs on contaminated pastures may need to be wormed from six weeks of age onwards. Ewes on safe grazing shouldn’t need worming again. Lambs on safe grazing shouldn’t need worming until after weaning.

She added that there may be a risk of Nematodirus battusas as a cold spring has been followed by a sudden temperature rise which could trigger a mass hatch of infective larvae on heavily contaminated pastures grazed by last year’s lamb crop.