Shorthorn has the highest purebred threshold in SteerJock — 15/16 instead of the usual 7/8 — plus a color rule that catches a lot of breeders off guard and the Durham Red composite for Red Angus crosses. Here's how it works.
The Three Tiers
Purebred Shorthorn. The top tier — 15/16 (93.75%) or higher Shorthorn. This is a higher bar than the 7/8 most breeds use. Carries forward as 100% for breeding purposes.
Durham Red. The Red Angus composite: 25% to 87.5% Shorthorn with the balance made up of Red Angus, and both parents registered. The balance must be Red Angus specifically — not black Angus. If your animal qualifies as Durham Red, it registers as that rather than the generic percentage tier.
ShorthornPlus. The appendix tier: 25% to 87.5% Shorthorn, with at least one registered Shorthorn (or ShorthornPlus) parent. This is the catch-all for crosses that aren't Durham Red.
How the Tiers Stack
The game checks them from purest down:
Purebred → Durham Red → ShorthornPlus
An animal slots into the highest tier it qualifies for. A 50% Shorthorn + 50% Red Angus animal becomes a Durham Red (the specific composite wins), while a 50% Shorthorn + 50% black Angus animal becomes a ShorthornPlus (the balance isn't Red Angus, so Durham Red doesn't apply).
Things to Know
The black rule
Shorthorn is a red, white, and roan breed. Black markings or a black coat signal Angus influence, so the registry caps any black animal at 50% (1/2) Shorthorn on paper — no matter its actual breeding. This is a cap, not a rejection: the animal still registers, just never above 50%. The practical consequence is that a black animal can never reach Purebred, since it's locked at half.
Highest purebred bar in the game
Most breeds reach purebred at 7/8 (87.5%). Shorthorn demands 15/16 (93.75%), so breeding up takes an extra generation of selection.
Durham Red is Red Angus only
Black Angus on the balance won't qualify — and combined with the black rule, it'll also cap your Shorthorn percentage at 50%.
Percentages round to 1/16
Shorthorn uses the sixteenths grid (6.25% steps), which is why the purebred threshold lands on 15/16.
It's paper percent, not genetics
Everything keys off the parents' registration papers, not raw genetic makeup. Register your foundation stock first.
Summary
Breed up toward 15/16 for Purebred. Cross with Red Angus in the 25–87.5% Shorthorn range for a Durham Red. Anything else 25–87.5% Shorthorn with a registered parent is a ShorthornPlus. Keep black out of the picture if you want a purebred — black animals are capped at 50%.