Drench Resistance Sheep Sustainability Strategy

March 2005
The aim of the Sheep Sustainability Strategy is to find sustainable best practise breeding and parasite management to combat rising levels of drench resistance among fine and medium wool sheep.

This new programme is directed by John Bates, farm consultant of Alexandra, and is backed by the MAF sustainable farming fund, Merino Inc, Mid-Micron wool group, Merino Breed Society, Corriedale Breed Society, Ravensdown, Zee-tag, Prattleys, Tru-Test and Fecpac International. The programme also involves Dr Jon Hickman from Animal Science dept, Lincoln University. Hickman says the rising level of drench resistance is alarming and common now in the sheep industry.

The programme started in November 2004 and is funded for three years. It involves faecal egg counting (FEC), blood testing, DNA profiling, weighing and recording the stud lambs from 45 ram breeders. Participants are looking for the drench and the parasite resistance/resilience status of lambs and their sires. Drench resistance is when one or more of the strains of internal parasites survive the dosing of anthelmintics and go on breeding with each other to create resistant strains, which adversely affect the sheep. Parasite resistance occurs in special sheep which are naturally immune to the adverse effects of the parasites, which can be genetically inherited, and passed on. This is different from sheep which are resilient, which means they continue to grow even when carrying large parasite burdens. These sheep are useful for breeding also.

The initial part of programme is drench and parasite resistance profiling on farms, doing faecal egg counting (FEC), weighing, dag scoring, blood sampling and constructing EBVs for tolerance to internal parasites, management plans for each stud and ram sale advice. Testing programme is to take six to 8 weeks all over the South Island as lambs and then again at 7/8 months. All lambs are tagged with EID tags for accuracy and data capture.

The second stage is putting all the information gathered into Sheep Improvement Ltd (SIL) and the Aussie Lambplan recording system (used by NZ Merino breeders), so that breeding indexes for resistance to parasites can be generated and compared within and across breeds.

The third part of the programme is all of the genetic science, looking for parasite resistance marker genes, which will then speed up breeding for resistance. Lincoln University is involved, through Jon Hickman, who developed the DNA test for footrot susceptibility.

Featured in this Rural Delivery story are:
Consultant John Bates and stud breeder Robin Wilson, with Corriedale lambs, showing the tagging, weighing and sampling procedures.