18/08/2026
For this week’s Trait Tuesday, we’re talking Worm Egg Count (WEC)—and why a high count in the paddock can actually turn into a massive win for genetic progress.
Here in MacGillivray on Kangaroo Island, our 500mm average rainfall creates steady background parasite pressure. We keep enough ground cover to protect our soils through the dry spells, which also gives worm larvae just enough of a microclimate to survive between seasons. It’s a constant, background challenge—making parasite resistance a non-negotiable trait for our climate.
The Paddock Reality Check:
We drenched our ’25 drop rams back in early June. Eight weeks later, we ran a routine bulk test ahead of Classing Classic and our upcoming ram sale ~15th October~.
The result? A 1,000 WEC.
Not what any seedstock producer wants to see right before sale time! But in genetic selection, you can't manage what you don't measure.
Instead of hiding from it, we pulled individual WEC samples across the whole group. To accurately select for low WEC ASBVs, you need a high enough natural challenge to expose genetic variation normally about 300epg... This 1,000 baseline allowed us to pinpoint which young rams naturally suppress worm loads and which ones carry them.
Why We Select for Low WEC:
Bred for KI Realities: Testing under realistic, 500mm rainfall conditions ensures our rams are proven under actual local challenge.
Cleaner Pastures: Low WEC sires pass on immunity to their lambs, dropping significantly fewer eggs back onto your feed.
Chemical Protection: Breeding natural resistance lowers drench reliance, protecting chemical efficacy and saving labor.
A raw spike in the paddock isn't a failure—it's the exact data required to breed tougher, high-performing rams for commercial producers.
How are your worm counts tracking after this winter? Are you selecting for WEC ASBVs in your ram team this year? Drop your thoughts below! 💬 👇
Some pics of the wool from our 2025 rams while sampling 🫣
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