Assessing communication tools to support parasite management

The aim of this project was to evaluate different ways of communication for their reach, impact and associated behaviour change. Parasite management is important for every livestock farmer and this topic was used to help evaluate five different communication methods. 

The project used:

  • analytics to assess the reach of the material
  • models to predict the impact of this parasite campaign
  • online surveys taken by participants immediately after viewing the material
  • online surveys taken by participants approximately 2-3 months later to assess if learnings from these communication methods was adopted.


Drench resistance is an increasing issue in New Zealand. Farmers need to have access to the most up to date information so informed decisions can be made for parasite management with the aim of preventing or reversing drench resistance on their farms. To do this, the information needs to be communicated effectively and have the desired impact. 

A variety of communication channels were used to provide information to farmers: 

Each of these channels of communication were evaluated for reach and impact on farmer knowledge, attitude, skills, aspirations and behaviour change. They were benchmarked against other B+LNZ comms messages. Additionally, the success of each communication method was compared to each other.

Key results

  • 251 farmers and 17 vets completed the initial survey and 29 farmers completed the follow up survey.
  • The podcast was the best performing resource with almost 2,000 downloads.
  • Farmers and vets noted that it was good to hear current farmers experiences rather than just theory from scientists.
  • Farmers recognised the need for multiple channels of communication that are targeted at various levels of knowledge.
  • 75% of people surveyed and who had viewed the resources planned to review or change their parasite management practices in the next 12 months.
  • Engaging with the resources appeared to increase farmer confidence.

Benefit for farmers

The benefits for farmers of this project were:

  1. Parasite management communicated in new and different ways with the aim of reaching a large audience. 
  2. Communication methods evaluated so future messages can get to farmers in the most useful way to support practice change on farm and invest wisely in communication.

Timeline and investment

This was a 6-month project completed in September 2021. B+LNZ investment was $45,000 over the duration of the project.



This project was funded by B+LNZ and partnered with Scarlatti.

Farmers involved: The Farmer Research Advisory Group (FRAG).

B+LNZ point of contact: Cara Brosnahan.

Definitions of some terms used in the resource material 

Drench resistance

Internal parasites, or worms, that are not killed by a correctly applied dose of drench are called drench resistant parasites. These resistant parasites then breed and pass their resistant genes onto their offspring. Over time this leads to an increase in the numbers of drench resistant parasites on your farm.

To know if you have drench resistant parasites, and what drench families the parasites are resistant to, you need to do a faecal egg count reduction test (FECRT). 


Faecal egg count, or FEC, is a tool to understand the parasite burden in your animal at any one point in time. A FEC involves collecting fresh dung, sending it to a lab or vet where the dung is treated and the eggs are extracted and counted using a microscope. The FEC is good at showing how many parasites are present, especially in young animals, but not what type of parasites are present.

Drench check

A FEC can also be known as a ‘drench check’ and should be carried out 10 days after drenching at least twice a year to confirm your drench and drench protocol is working. If eggs are present in a drench check there could be resistant parasites on the farm.

Larval culture

A FEC can be cultured (the eggs hatched) by a lab to see what different types of parasites are present in your animals. A larval culture is conducted as part of a FECRT and maybe a drench check.


A faecal egg count reduction test, or FECRT, is a test to understand the effectiveness of the drench you are using and to know the drench resistance status of your farm. A FECRT should be performed every 2- 3 years (or more frequently if you suspect a problem) and involves the following:

1.       Collect a fresh faecal sample just prior to drench (pooled from approx. 10 animals)

Send away for testing to see:

  • how many eggs are present
  • what kinds of parasites are present.

2.       Drench groups of animals with all drench families wanting to be tested (e.g. BZ, levamisole, a triple combination)

3.       Collect fresh faecal samples from each drenched animal 7-10 days later

Send away for testing to see:

  • how many eggs are present
  • what kinds of parasites are present.

An effective drench will be killing at least 95% of the parasites present. If you think you have a drench resistance issue, follow up with your vet for advice.


Refugia is the practice of leaving some parasites in ‘refuge’ from drench. The aim of refugia is to dilute out the parasites resistant to drench with parasites susceptible to drench.  This can be done in many ways, for example:

  • leaving a portion of the mob undrenched.
  • not drenching your adult ewes unless there is a demonstrated need to
  • Not drenching young stock at intervals less than 28 days and, if appropriate, extending the drench intervals of young stock (Note, careful and regular monitoring of FEC is required when extending drench intervals past 28 days).

Drench families

Drenches are divided into several ‘chemical family’ groups that each have a different way of acting to kill the parasites.

These families are:


Common names

Chemical actives

Examples of NZ products*

  • Macrocyclic lactones
  • ML’s
  • Mectins
  • Abamectin
  • Ivermectin
  • Moxidectin
  • Doramectin
  • Eprinomectin
  • Cydectin
  • Clomax oral
  • Eprinex PO
  • Exodus
  • Genesis
  • Benzimidazole
  • White drenches
  • BZ’s
  • Albendazole
  • Fenbendazole
  • Oxfendazole
  • Bomatak C
  • Oxfen C Hi-mineral
  • Levamisole
  • Clear drenches
  • LV’s
  • Levamisole
  • Gold drench for Cattle & Sheep
  • Amino-acetonitrile derivative
  • AD
  • Monepantel
  • Zolvix plus (also includes Abamectin)
  • Spiroindole
  • SI
  • Derquantel
  • Startect (also includes Abamectin)

*B+LNZ does not endorse specific brands, these are presented here as examples only.

Worm/parasite types

See page 14 of the Wormwise handbook for details on all parasites. Below is a list of the most common internal parasites present in New Zealand livestock:

Haemonchus contortus 

Barber’s pole

  • Primarily a parasite of sheep and goats
  • Blood-sucking 
  • Can lay up to 10,000 eggs per day
  • Danger period late summer and autumn

Ostertagia (Teladorsagia) circumcincta 

Brown stomach worm

  • Primarily a parasite of sheep and goats
  • Can lay 50-100 eggs per day



  • Stomach hair worm or black scour worm
  • Affects sheep, cattle, horses and pigs
  • Can be very damaging in sheep
  • Danger period is winter


Thin-necked intestinal worm

  • Danger period is early spring and throughout summer

Ostertagia osertagi 

Medium stomach worm

  • Most significant worm for NZ cattle 
  • Type I 
  • Causes scouring and weight loss 
  • Danger period summer and autumn 
  • Type II 
  • Can cause sudden and severe illness, sometimes sudden death 
  • Danger period usually spring in cattle 9-12 months or older 


Parasitic roundworm

  • Small intestinal worm 
  • Can be a problem in intensive cattle farming  
  • Most common in autumn

Quarantine treatment

Quarantine treatment is used to make sure any stock coming onto your property do not carry resistant worms with them. A quarantine drench should contain one of the new actives, monepantel or derquantel as well as another drench family, for example a macrocyclic lactone (e.g. abamectin). It should not be the same drench as you use for regular drenching. These animals should then stay off pasture for at least 24 hours either in yards if feasible or be put out onto dirty pasture you know contains parasites. 

Knockout drench

Knockout drench is when you substitute a routine drench with a drench containing monepantel or derquantel (the same drench as you would use during a quarantine drench). It is important this is given at the right time to be most effective on your property – generally late summer/early autumn to prevent an autumn larval peak of resistant parasites on pasture. The purpose of a knockout drench is to remove any parasites that survived your ‘normal’ drench treatment.

Exit drench

Exit drench is a drench (usually a triple combination, or a drench containing monepantel or derquantel) given to an animal treated with a long-acting drench or capsule after the protection period has finished. The purpose of this drench is to kill parasites that have survived a long-acting drench or capsule treatment.