Kolbroek, the PORCUS Grid and Fat Quality

#Graded down at half weight

In a controlled feeding trial at Elsenburg, Kolbroek pigs were taken from about 20 kg on a commercial grower diet. At the end of it, the ad-libitum group had reached a live weight of 57.25 kg — barely half what a commercial pig is sold at — and their carcasses measured 24.7 mm of P2 backfat, with a calculated lean meat content of 64.50%.

That is a class C carcass. Not at market weight. At 57 kg.

The trial is the honest South African record on this breed (Hoffman, Styger, Brand & Muller, SA-Anim Sci 2005), and if you intend to run hardy indigenous genetics in South Africa it is the number that decides your business model. Not because the pig is bad. Because the pig is being measured against a grid built for someone else's customer.

South African specifics

The Elsenburg indigenous-breed trial, 67 days, n = 12 per breed, from about 20 kg start weight (Hoffman et al. 2005):

	Kolbroek, ad lib	Kolbroek, restricted	Windsnyer-type, ad lib
Average daily gain	0.442 kg/day	0.323 kg/day	0.299 kg/day
Feed conversion ratio	4.07	—	3.52
Warm dressing %	83.8%	79.7%	—
Carcass P2 backfat	24.7 mm	—	—
Calculated lean	64.50% → class C	61.08% → class S	66.95% → class R

Kolbroek grew faster than the Windsnyer type and dressed out extremely well. It also converted feed worse — 4.07 against 3.52 — and it laid fat early. Both things are true at once, and the second one is the one the market prices.

#PORCUS: read the grid, then read your own carcass into it

South African pork carcasses are classified under the Agricultural Product Standards Act 119 of 1990, with SAMIC as the assigned body. The grid is PORCUS; the letters are the classes:

Class	Lean meat content	Backfat
P	≥ 70%	≤ 12 mm
O	68–69%	13–17 mm
R	66–67%	18–22 mm
C	64–65%	23–27 mm
U	62–63%	28–32 mm
S	≤ 61%	> 32 mm

Backfat is measured at a defined point: 45 mm from the carcass midline, between the second- and third-last rib. That single measurement, run through a prediction formula, determines your class and therefore your price.

The arithmetic on that Kolbroek carcass, using the optical or intrascope formula prescribed in GN R.1748 of 26 June 1992:

%LMC = 74.4367 − 0.4023 × fat thickness (mm) = 74.4367 − (0.4023 × 24.7) = 74.4367 − 9.937 = 64.50% → class C

Run it backwards and the grid becomes a management tool rather than a verdict delivered at the abattoir. Class R starts at 66% lean, so the fat measurement must come in at or below about 21 mm:

74.4367 − 66.00 = 8.4367 ÷ 0.4023 = 21.0 mm

Now you know the number you are managing to, and you can probe your own pigs against it before you load them.

#The paradox: the grid pays least for the best bacon

Hugo and Roodt measured fat quality across the classification groups using iodine value, the standard index of fat softness. Their finding runs directly against the price schedule.

Mean iodine value fell from 73.5 in class P to 69.8 in class S. Lower iodine value means firmer, more saturated, more stable fat. Their conclusion is explicit: the C, U and S groups — backfat between 23 mm and over 32 mm — "possessed good technological quality backfat", while the P and O groups — under 17 mm of backfat — "could not conform to international standards proposed for good technological quality backfat".

Contested — here is both sides

Is the PORCUS grid wrong?

The case that it is. It pays most for the fat that fails international firmness standards and least for the fat that meets them. A producer selling charcuterie is penalised for producing exactly the raw material charcuterie requires.

The case that it is not — and this is the stronger argument. The grid was never built for a charcutier. It was built for a supply chain selling lean fresh cuts into a price-sensitive mass market, where soft fat is a genuine processing and shelf-life defect and where consumers demonstrably buy lean. Measured against its own buyer, the grid is doing precisely what it should. July 2026 showed what kind of market that is: imported pork ordered during the disease disruption landed just as domestic supply recovered, and the farm price fell by roughly a quarter in five months (Business Report, 23 July 2026). A commodity market writes a commodity specification.

The synthesis. The lesson is not "the grid is wrong". It is "the grid is a contract with a customer you may not have." Decide who your customer is. Then decide whether to be measured by that contract at all.

#Say the growth penalty in matched units, or someone will correct you

Every pastured-pork slide deck runs the same comparison: twelve months outdoors against six months commercially. It is usually stated in a way that is not defensible.

A working South African outdoor operation publishes its own figures: a cross-bred pig "slaughters out at ±40 kg after 12 months, perfect for fresh cuts, and 100 kg+ after 18 months, perfect for curing" (Wickedfood Earth, Magaliesburg). Slaughters out at is a carcass weight. The commercial benchmark everyone reaches for — about 100 kg in six months — is a live weight. Side by side, they compare two different things.

Convert. At the dressing percentages the Elsenburg trial measured for these types — roughly 78% to 84% — a 40 kg carcass is somewhere near 50 kg live. So the honest sentence is:

This outdoor system takes about twelve months to produce a pig at roughly half the live weight a commercial pig reaches in six.

Still a severe time-and-feed penalty, and still the entire economics of pastured pork here — but now a statement nobody can knock down. (The farm does not say whether that ±40 kg is warm or cold, so treat the conversion as approximate.)

#Feed is the business. Forage is a rounding error you must still measure.

Feed runs at roughly 70–80% of pig production cost — sources differ, and none is a South African cost-of-production study, so use the magnitude, not a decimal. Everything else is noise around that number. So the two levers that matter are the feed price and the feed conversion ratio, and an outdoor system is structurally worse on both: hardy genetics convert worse, slow growth means more maintenance days per kilogram sold, and a pig that is too cold or too hot eats more to stand still.

Do this on the farm

Budget forage honestly.

Treat pasture and farm by-products as a ration cost-reducer of 10–30% at best, not as a ration.
Prove your own figure by weighing pigs, not by asserting a percentage. Weigh in, weigh out, record the concentrate delivered between the two.
Green forage — kikuyu, lucerne, clover, chicory, brassicas — earns its keep with gestating and dry sows, which tolerate bulk and fibre. It does very little for weaners and finishers.
Never build a business plan on the forage saving. Build it on the concentrate cost; the saving is upside.
Formulate the concentrate with a registered animal nutritionist. Feed additives and medicated feeds are registered products under the Fertilizers, Farm Feeds, Agricultural Remedies and Stock Remedies Act 36 of 1947 — the label and your veterinarian govern what goes in and what the consequences are for the animal you sell.

#Disease is a working-capital event, and 2026 proved it

The last lesson treated foot and mouth disease as a legal duty. It is also a cash-flow shock, and it lands without a single pig on your farm getting sick.

What it costs, what it earns

The five-month price swing on the same pig (all prices excl. VAT, dated).

February 2026, Western Cape Department of Agriculture national producer series: bacon pigs R40.30/kg, porkers R40.59/kg, sausage pigs R31.91/kg — the bacon price up 24.5% on February 2025's R32.37/kg (WCDoA Pork Monthly Report 2026/02).
27 July 2026, consolidated farm-gate table: baconers R30.22/kg, porkers R28.61/kg (AgriOrbit).
Eskort's chief executive, quoted on 23 July 2026, put the farm price fall at about R40/kg to about R30/kg, against a long-run average around R32/kg, with retail pork chops falling from about R120/kg to about R80/kg (Business Report). That is one executive's statement to the press, not a published price series — but it moves in step with the AgriOrbit table, so the direction is not in doubt.

That is roughly a 25% revenue swing in five months, on an identical carcass. Note also that there is no reliable published South African average pork carcass mass — the figure most often quoted comes from an undated commercial web page. Work your margin per kilogram and multiply by your own carcass weights.

The causes are instructive. Import cover ordered during the ASF and FMD disruption arrived on an eight-to-ten-week lag at the same moment domestic supply recovered — and on 8 July 2026 the FMD section 9 holding period for pigs was cut from 90 days to 42 days, releasing market-ready pigs into an already-full market. Meanwhile the underlying disease damage was severe: roughly 16 FMD outbreaks in commercial piggeries since late 2025, affecting about 12 700 sows, alongside about 5 900 sows culled for ASF near Pretoria (3tres3).

For a small producer the lesson is not the price chart. It is that an FMD holding period can strand finished pigs on your farm for weeks while you keep feeding them, and that the release of those pigs then floods the price you were waiting for. Holding periods and controlled-area boundaries change by Government Notice; confirm the current position with the state veterinarian before every consignment and never plan against a fixed number.

#Before you bet the farm on the curing chamber

Two cautions the fat-quality finding does not remove.

Nobody has measured what South Africans will pay for it. No peer-reviewed willingness-to-pay figure for pastured pork could be located here. The technological case for class C, U and S fat is published; the premium is not. Assume none until a named customer has paid you one, twice.

The carcass still has to come out of a registered abattoir. Section 7 of the Meat Safety Act 40 of 2000 prohibits slaughter outside an abattoir, and the own-consumption exemption expressly forbids selling any of that meat to any person. The registration route for on-farm curing is not something this course can hand you — confirm it with DALRRD and your municipality before you build a chamber.

#What to do on Monday

Phone the abattoir you intend to use and ask two questions: which grading instrument do you use, and will you send me the classification slip. Then take the matching formula and work out the backfat measurement that keeps you inside the class you are aiming for. If your genetics cannot get there, stop trying to hit the grid — and go and find out, with a real order rather than a hope, whether a customer will pay you for the fat instead.

#Check yourself

3 questions — answers explained as you go

1An abattoir using an optical probe measures 26 mm of backfat on your carcass. Using the GN R.1748 formula, what class is it, and what does that mean for a curing business?
Why: Run the formula: 0.4023 × 26 = 10.46, and 74.4367 − 10.46 = 64.0% lean, which is class C (64–65% lean, 23–27 mm). The classes the grid pays least for — C, U and S — are the ones whose fat met international firmness standards, while P and O fat did not. Mean iodine value fell from 73.5 in class P to 69.8 in class S.
2Why can you not use the Hennessy Grading Probe formula on a measurement taken with an optical probe?
Why: The optical formula is %LMC = 74.4367 − 0.4023 × fat. The Hennessy formula is %LMC = 72.5114 − 0.4618V + 0.0547S, where S is muscle thickness. The measurement point is the same — 45 mm from the midline between the second- and third-last rib — but the instruments read different things, and an error of a percentage point or two moves a carcass a whole class.
3A pastured-pork slide claims "our pigs take 12 months to reach 40 kg, versus 100 kg in six months commercially — a threefold penalty". What is wrong with the claim?
Why: Matched units matter more than the size of the penalty. "Slaughters out at ±40 kg" is a dressed figure; the commercial benchmark everyone compares it to is live. Converting at the dressing percentages Hoffman et al. measured gives about 50 kg live. The penalty is still severe; it is now also defensible.