The problem for sheep is similar to problems that people encounter. Just as some infections in people won't respond to antibiotics, the worms in sheep also become resistant to drugs. In the New England area of NSW, the first case of Barber's Pole worm resistance to the drug ivermectin has just been reported. This is a major cause for concern for woolgrowers in the region as Barber's Pole worms are also resistant to the other main drug, closantel. The Barber's Pole worm lays thousands of eggs, and in warm moist conditions many of these survive on pasture and infect grazing sheep.
Heavy infestation causes acute anaemia and blood loss in sheep, leading to death.
We have developed methods for detecting individual rams which are quite resistant to worms. Graziers can then select rams that are worm resistant for use in their breeding programs. Project Nemesis involves collaboration by 11 Merino sheep studs in all mainland states of Australia. The breeders involved in the project will report on their activities and progress over the past three years at a workshop in Melbourne on Wednesday, August 20, 1997. Breeder, Mr Michael Pocock, from Panlatinga Merino Stud in South Australia includes information about each ram's resistance to worms along with other production traits in his annual sale catalogues.