16 November 2001

Parasites still a threat even on cleared pasture

By Marianne Curtis

ALTHOUGH some pastures may have been free from sheep for many months this year, they could still be contaminated with parasites.

That is the warning from Andy Forbes, senior technical services manager at Merial Animal Health. "It is virtually impossible to eradicate most types of parasites from farms, particularly worms, so routine control measures should continue after restocking."

But flocks culled early in the foot-and-mouth crisis will have clean pastures and could take advantage of the opportunity this offers for improved parasite control, in consultation with their vet, according to SAC vet investigation officer Graham Baird.

"Pastures on farms culled in March or April, particularly where cuts of silage or hay were taken, will have very low worm burdens, offering the possibility of reduced anthelmintic use next year. But for those culled later, where lambs were already born, worm eggs could be present in numbers which may pose a risk to next years lamb crop."

Parasite control should be discussed on an individual farm basis with vets – as every farm is different – but it is sensible to maintain usual control measures, says Merials Roddy Webster. "Pastures may be cleaner, but nothing is 100% and some parasites can survive. Buying in ewes with worm burdens can also quickly contaminate clean pasture."

Adopting rigorous parasite control measures with bought-in ewes should help minimise parasite burdens next spring, says Mr Forbes. "When ewes arrive on farm, check for parasites by taking dung samples for vet inspection.

"Treat with an endectocide and – when ewes are from a fluke area – a flukicide. After 7-14 days, take further dung samples to check ewes are clear of parasites."

While inspecting and treating for parasites and other diseases, incoming ewes should be quarantined away from the rest of the flock for a minimum of three weeks, advises Mr Forbes.

"Aim to equalise the health status of bought-in sheep with that of sheep already present on the farm. New sheep which are naive to diseases in the existing flock will be susceptible to these, whereas sheep already on-farm could catch diseases from bought-in sheep.

"When buying sheep, try to find out as much as possible about their health status. Ask about disease history, health scheme membership and what they have been vaccinated against." &#42

PARASITE CONTROL

&#8226 Pasture could be contaminated.

&#8226 Take dung samples.

&#8226 Treat bought-in ewes.