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Completing a Faecal egg count reduction test (FECRT)

What do you need to do?

The purpose of a FECRT is to inform you about the drench resistance status of the parasite population on your property. This will help ensure that the drenches you use on your property are highly effective.  A significant driver of drench resistance is the continued use of ineffective drench products.

 The most important thing you need to do is discuss your plans with one of our sheep and beef vets.  We will add you to the FECRT list that we have been assembling all season and this will ensure you are sent all the information and tags you require.  The test itself is easy and quick, however a successful test relies on you presenting a large enough group of ‘wormy lambs’.  Our standard pre-test advice is to:

  • Identify 100 “drench test lambs” prior to weaning with a FECRT tag (we provide these) and do not drench them prior to or at weaning.
  • Once weaned, graze these drench test lambs hard behind a larger mob of lambs so that they pick up a significant worm burden.

If you need to complete a test this season, or if you just aren’t sure about the process, give us a call.  We are happy to identify the best drench testing option for your farm.

The summer of 2018/2019 was a busy one for FECRT of sheep.  A high-level summary of the results of 15 North Canterbury FECRT’s are presented in the table below.  It showed 87% of tested farms had a major parasite species that was resistant to a BZ (white) drench.  The key messages that you should take away from these results:

  • Drench resistant parasites are common on North Canterbury sheep properties
  • Drench resistant parasites are not just resistant to one family but parasites resistant to combination drenches are now common on many properties

Drench Test Group

Percentage of farms with a 'FAIL' result (<95% efficacy in a major worm species)

Oxfendazole (BZ)


Levamisole (LEV)


Abamectin (ABA)


Arrest (BZ/LEV combination)


Switch (ABA/LEV combination)


Using an ineffective drench allows lambs to remain parasitised despite you drenching them. This can cost you production and money and is a major driver for increasing the proportion of drench resistant worms on your farm. 

You can’t afford to be drenching with a product that doesn’t work.

About the author

North Canterbury Vets are a mixed practice which deals with dairy cows, beef, sheep, deer, horses and alpacas as well as companion animals. Our team has an ethical focus to assist in developing and growing our clients' businesses and providing quality health care to ensure that their livestock and pets live healthy and productive lives.

Our Clinics

North Canterbury Veterinary Clinics operates four clinics throughout the Hurunui region.