IT is possible to select ewes and rams for resistance to parasites, according to research at the Roslin Institute.
"The evidence supports that it is a good idea and there are New Zealand and Australian schemes where they do it," says researcher Stephen Bishop.
His studies show that using faecal egg counting shows which ewes are more resistant to parasite infection post-lambing when the infection risk is highest, and it is a heritable trait.
"It will be costly, but in NZ it is cost-effective. And if a flock is selected for resistance to nematodes it could give the opportunity to run it as organic, with no worm treatments."
Prof Bishops results also reveal that ewes rearing twins have a much higher faecal eggs count post-lambing than those rearing singles. "Ewes rearing twins have a large maternal parasite load and you should try to avoid grazing lambs on land where twin ewes have been in early lactation. This will reduce the lambs exposure to parasites." *