ParaBoss News - March 2019 - State Outlooks

The Quick Quiz

This quick quiz tests your knowledge of sheep and goat parasites and their control. 

1. There are two common species of black scour worm, which one is more pathogenic and in what environments is it more common?

2. How can you use a paddock while it is being made low worm-risk?  

3. When hand jetting, what is a good indicator that the jetting fluid is being applied effectively?

4. Describe the withholding periods that apply to fly treatments.

>> Check the answers.

ParaBoss Job Vacancy

ParaBoss is hiring: ParaBoss Technical and Extension Manager

Part time, flexible location and hours. >> Read more.

State Outlooks for March 2019

From the editor

Much of the country is continuing dry with the prospect of an El Niño weather pattern during autumn and winter.

Producers in the eastern states contending with dry conditions might find value in the NSW state comments of the NSW district veterinarians Charlotte Cavanagh (Bourke), Jillian Kelly (Coonamble) and Erica Kennedy (Nyngan) regarding the correct diagnosis and treatment of scouring, or poor-doing sheep.

You may also like to revisit this article on worms in drought, as well as note the warning below.

Warning: drenching in drought is a leading cause of drench resistance!

Producers who need to drench sheep during these drought conditions should strongly consider using a 100% effective “quarantine drench” protocol, but also avoid drenching a whole adult mob (except where barber’s pole is an issue)—where possible, do not drench about 10% of the mob—make this judgement as you drench based on body condition and strength.

Why? After months of hot dry conditions with little pasture cover to protect larvae there is likely to be negligible worm larvae on the pasture; most worms on a property will be in the sheep! If the sheep are drenched before it rains, only drench-resistant worms will be in the sheep to reproduce and then contaminate the pasture when it next rains. Drenching under these conditions can therefore rapidly increase drench resistance on your property.

If a 100% effective drench is used, no resistant worms will be left in the sheep and only the odd ones from before (more susceptible worms) will be on the pasture. If not all sheep are drenched, the more susceptible population of worms those sheep are carrying will be the ones to start a new population rather than a highly resistant population left after a less than effective drench. Aim to leave a maximum of about 50 eggs per gram after treatment of these less-resistant worms—this won’t affect the sheep, but will help manage drench resistance.

[To calculate the number of sheep to leave undrenched based on a worm egg count: 5000 divided by your pre-drench worm egg count. example 1: 5000/200 epg = 25% to leave undrenched; example 2: 5000/450 epg = 11% to leave undrenched.]

If drenching is being considered, do a WormTest first, as worms may not be the problem. If drenching is indicated, choose an appropriate combination drench (or concurrently use more than one drench) with at least 4 highly effective components—one of these, if not two, should be monepantel (Zolvix®) or derquantel (Startect®).