Article summary: Around big genetics days like the National Merino Auction in Graaff-Reinet, it’s worth pricing the hidden “feed bill” behind an upgrade. This article gives you a simple framework to translate higher targets into intake, pasture demand, and a rotation plan, then sanity-checks it using growth-rate tracking in Pasture.io.
The National Merino Auction in Graaff-Reinet (Eastern Cape, 15 August 2025) is the kind of day that makes you think bigger: better rams, better replacements, higher targets.
But there’s a catch that quietly makes or breaks the return: genetics don’t perform on good intentions, they perform on nutrition. Even in well-run systems, sheep often fall short of genetic potential because the nutritional plane doesn’t consistently match what the animal needs through the production cycle.
And when nutrition pinches, wool is one of the first things the animal compromises. Poor or inconsistent feeding can reduce wool growth and create diameter variation that hurts staple strength and specification.
The hidden “feed bill” behind a genetics upgrade
When you buy better rams (or keep better replacements), you are usually aiming for at least one of these outcomes:
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More lambs reared
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Faster lamb growth
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Heavier, more valuable fleeces
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More consistent wool quality
All of those outcomes need more nutrients, delivered more consistently. Wool growth responds to nutrient supply, and key limitations are often amino acids and overall nutrient availability.
So the practical question becomes:
What extra pasture grown or conserved feed do you need to justify the genetics upgrade?
You can answer that without turning it into a PhD.
A simple framework that keeps you honest
Target performance → required intake → pasture demand → rotation plan
1) Target performance: choose one “upgrade target” you will manage for
Pick the single performance lever you actually expect genetics to lift first. Examples:
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Lift scanning-to-weaning conversion by X%
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Lift fleece weight by X kg clean per head
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Hold micron and staple strength by avoiding the winter/spring dip
The point is not perfection. It’s clarity.
2) Required intake: what does that target demand nutritionally?
In most situations, energy or protein are the main constraints on production, and requirements change with liveweight and physiological state.
The “gotcha” period is typically late pregnancy and early lactation where requirements can jump sharply (often several-fold), and ewes can struggle to physically eat enough pasture to match demand.
If your genetic upgrade is meant to lift reproduction and lamb output, this is where the feed bill usually shows up first.
3) Pasture demand: turn intake into kilograms of dry matter per day
You don’t need perfect numbers. You need a directionally correct check:
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Extra intake per head per day (kg DM)
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× number of head
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× number of “pressure days” (often 45–90 days around the critical period)
= extra feed required (kg DM)
Quick example (illustrative only):
If your upgraded ewe flock needs just 0.25 kg DM/head/day extra during a 60-day pressure window, and you’re running 1,200 ewes:
0.25 × 1,200 × 60 = 18,000 kg DM (18 t DM) of additional feed you must grow, save, or buy.
That’s the hidden feed bill you’re committing to when you lift targets.
4) Rotation plan: where does that extra feed come from, week by week?
Now convert “extra feed” into a plan you can execute:
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If pasture growth can cover it: set rotation length and paddock allocation to protect residuals and keep quality consistent.
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If pasture growth cannot cover it: decide early whether you will conserve feed ahead of time, supplement, reduce stocking pressure, or use a containment option.
This matters for wool. Big swings in nutrition can create fibre diameter variation and tenderness, which can weaken staple strength.
The sanity check that stops expensive regret: growth rate vs demand
This is where most genetics ROI falls over, not in the ram catalogue.
Ask yourself one plain question each week:
Is my farm growing enough feed to support the new target without stripping condition or sacrificing pasture?
You can do that with two numbers:
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Farm demand (kg DM/day)
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Farm supply (kg DM/day)
Supply is simply:
Pasture growth rate (kg DM/ha/day) × effective grazed hectares
If supply is below demand for weeks at a time, the system will “pay the bill” by:
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pulling ewe condition down (reproduction and lamb survival pressure)
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pulling wool output down (and potentially staple strength)
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pulling pasture base down (slower recovery later)
Pasture.io tie-in: use growth-rate tracking to test the upgrade before it bites
Pasture.io helps you keep the genetics decision grounded by tracking whether your feed base can actually support higher targets.
A practical weekly routine:
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Check growth rates (farm and key paddocks). Are you trending up, flat, or falling?
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Compare growth vs demand for the class of stock carrying the genetic “upgrade target”.
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Adjust the rotation before you see the problem in body condition or wool.
If the growth-rate trend says you are consistently short, you have an early warning to pull levers (supplement, conserve, change allocation, reduce pressure) before the underfeeding cost becomes real.
A short “before you upgrade genetics” check
Keep this simple. If you can answer these, you’re in a strong position:
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What single performance target will you manage for first?
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What is the critical 45–90 day window where nutrition must not dip?
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How many tonnes of extra feed does the target require over that window?
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Can your expected pasture growth supply it, on average, in that period?
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If not, what is your planned source of extra feed (conserved, bought, containment, stocking pressure change)?
The takeaway
Paying for genetics is visible. Paying for underfeeding is sneaky, and it compounds.
If you want better rams to show up as better wool and better livestock performance, treat the genetics decision like a feed decision first: set the target, translate it into intake, convert it into pasture demand, then build a rotation plan that your growth rates can actually support.
- The Dedicated Team of Pasture.io, 2025-08-19