31 May 1996

…but worm risk high

LATE-born lambs are at increased risk of nematodirus infection given the recent wet conditions warns farmers weeklys Stock Health parasitologist, Gordon Graham.

Eggs of this worm, which can cause explosive outbreaks of scour and death in young grazing lambs, are now hatching, says Mr Graham.

Risk is above average this season for the first time in 10 years due to the late spring. This has delayed hatching of eggs until now when most lambs are eating grass.

Outbreaks will be most severe in six to 12-week-old lambs on pasture grazed by sheep last year. Symptoms include loss of appetite and condition and diarrhoea. Control is needed to prevent lambs losing condition and dying.

For best results graze this years lambs on pasture not grazed by lambs last spring. When this is not possible dose routinely with effective wormers.

ADAS sheep specialist Lesley Stubbings also stresses that nematodirus risk is expected to be above average this year but urges caution before accepting worm infection as the only cause of dirty backends and scouring.

"Im not sure what were seeing in some of these lambs is worms," says Dr Stubbings. "Some dirty backends might be stress-induced. When ewes are struggling, the lambs are perhaps piling into grass which is becoming much lusher.

"So draw breath before panicking and dosing lambs that were only treated a fortnight ago. If youre on a regular worming programme but still feel there are lambs that shouldnt be dirty, ask the vet or VI centre to check dung samples for egg counts," she says. "It might not be worms youre looking at."