What cost worms?

The cost of sheep worms in Australia

Stephen Love
Veterinarian/State Coordinator-Internal Parasites
NSW DPI – Armidale District Office

Some of the most important things in life are ticking over in the background, not demanding attention, passing almost unnoticed.

Worms in livestock are a bit like that. Or perhaps like an iceberg, with its tip easily visible, but most of its mass hidden beneath the surface.

External parasites, such as lice, fly maggots or ticks are much easier to see. In the plant world, weeds are obvious, as are diseases and deficiencies in crops. Not so worms, unless you have deaths, dags or clinical disease.

Worms are the quiet achiever. Sheep worms for example were recently estimated to cost the Australian sheep industry $369 million per year (MLA report, 2006). This puts worms as the number one health problem of sheep, followed by flies and lice, and footrot. But strangely, when biosecurity is discussed, internal parasites are often not mentioned.

Of the $369 million, $300 million is from production losses, more than $3 per sheep on average. These losses are subtle and often invisible, but nonetheless significant. Most of this goes unnoticed because most producers don’t regularly monitor worm burdens using worm egg counts (‘WormTests’). As they say, if you don’t measure it, you can’t manage it.

Aiding and abetting worms is drench resistance. Like worms, this problem goes largely unnoticed, and unmonitored. By the time your sheep give clear signs that your drench is failing – deaths, dags, and illthrift – resistance to the drench is already very advanced. And you have already lost a lot of money.

Virtually all Australian sheep farms have drench resistance to some degree, but a small minority test for it. There are two ways to test for drench resistance. The best is the ‘faecal egg count reduction test’, or DrenchTest. This takes a bit of effort, but the pay off is very good. A simple and quick method is the DrenchCheck, which is simply a WormTest done on a mob of sheep 10-14 days after a drench. You don’t even have to yard the sheep: just collect clean and very fresh dung samples out of the paddock and send them off to the lab – or DIY – for a worm egg count.

The benefits of regular worm egg counting far outweigh the costs, so it’s strange that more people don’t do it. ‘One of life’s mysteries.
Published in:
The Land, WormBoss News -Sept 08, Guide for graziers, Arm RLPB News

Sackett D et al 2006-Economic cost of endemic diseases of beef cattle and sheep in Australia (abbreviated title). Retrieved from http://www.mla.com.au (but may not be currently available).