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Rick and Jenny Robertson, Bengworden, VIC

Bengworden, near Bairnsdale, Vic
WormBoss Region:
Victorian Winter Rainfall
Merino Wool and Prime Lamb production


Key point:

  • Worm egg counts are important practical tool to estimate the burden of adult worms in monitored sheep.

Rick & Jenny's Story

Wetter than usual conditions across much of the eastern seaboard, coupled with warm temperatures, means 2010 promises to be a bumper year for wool and sheep producers.

But they are also being warned to keep a close eye on worm burdens in their flocks or risk production losses up to $16,000 for every 5,000 head.

With at least average rainfall expected to continue through autumn, pasture growth is already excellent.  However, few producers realize that internal parasites are already having a significant impact.

Victorian wool and prime lamb producers Rick and Jenny Robertson are one couple who won’t risk production losses as a result of internal parasites in their flock.  Running a 1000-hectare property at Bengworden near Bairnsdale, they have been using WECs for several years.

“Managing against drench resistance was an increasing problem for us about three years ago.  So we did a test and discovered that certain drugs were losing their efficacy,” Mr. Robertson says.

The couple now does worm egg counts regularly to monitor worm burdens and effectiveness of drenches.

“I don’t routinely drench according to a calendar as this is an unnecessary cost and results in drench resistance,” Mr. Robertson says.

Research demonstrates that most sheep farms have some degree of drench resistance and most have resistance to more than one class of drench.  A worm egg count 10 to 14 days after drenching will confirm (or otherwise) that the drench was indeed effective.

Testing provides early warning of the worm burden, and can also cut the number of drenches required, saving time and money.

Worms are the number one challenge to sheep in Australia, costing the industry about $300 million each year.  More than 80% of this cost is due to production losses, which are often subtle and go unnoticed.

By the time worm infections are obvious whether through anaemia and deaths in the case of barber’s pole worm and liver fluke, or scouring from scour worm infections, production losses can be substantial.

While a drop of 70 to 100 grams in wool growth or one to two kilograms of weight gain may not be noticed, they will cause losses of the $7,000–$14,000 in a mob of 5,000 sheep.

For many, the losses will be even greater—in the $4 per head range—as a result of poor diagnosis and drench choice.  It is a cost a few producers can afford.

Using worm egg counts, producers can at least halve production losses due to worms.  Despite this, only 24% of producers use such tests regularly, meaning most leave the management of their worm burden to guesswork.