Santa Gertrudis is a breed-up breed in SteerJock — there are no Gen 0 Santa Gertrudis. What makes it unusual is that there are two completely different ways to reach Purebred: the original 3/8 Brahman + 5/8 Shorthorn ratio, or the STAR 5 grading program that climbs by Santa Gertrudis percentage. Every tier must be red. Here's how it works.
The Tiers
Purebred Santa Gertrudis. The top tier, reachable two ways: an animal at exactly 3/8 Brahman + 5/8 Shorthorn (the original founding ratio), or any animal at 87.5% or higher Santa Gertrudis on paper (a STAR 5 Level III graduate). Both parents must be registered. Carries forward as 100% Santa Gertrudis.
STAR 5 Level II. 75% to 87.4% Santa Gertrudis on paper, with at least one registered Santa Gertrudis parent. The last rung before purebred.
STAR 5 Level I. 50% to 74.9% Santa Gertrudis on paper, with at least one registered Santa Gertrudis parent. The entry rung of the grading ladder — a purebred crossed onto another breed lands here.
Foundation Santa Gertrudis. The origin-path ladder — an intermediate Brahman × Shorthorn cross that has both breeds present but hasn't hit the exact 3/8 + 5/8 ratio yet. Requires both parents registered (Brahman, Shorthorn, or Santa Gertrudis). These are the stepping stones toward your first purebred.
The Two Paths to Purebred
The origin path (building the first one). Since there are no Gen 0 Santa Gertrudis, you bootstrap the first purebred from Brahman and Shorthorn. Cross registered Brahman and Shorthorn into Foundation animals, then breed toward exactly 3/8 Brahman + 5/8 Shorthorn. A red animal at that ratio with two registered parents registers as Purebred.
The STAR 5 path (grading up). Once a purebred exists, you grade other red cattle up to purebred by percentage. A purebred crossed onto another breed gives 50% (Level I); breed that back onto a purebred for 75% (Level II); breed again for 87.5%, which graduates to Purebred. Three generations of top-crossing onto purebreds takes you from Level I to full purebred.
How the Tiers Stack
The game keys off Santa Gertrudis percentage first, then the origin ratio:
Purebred → STAR 5 Level II → STAR 5 Level I → Foundation
Once a purebred exists, everything runs on the STAR 5 percentage ladder. The Brahman/Shorthorn origin ratio only matters for bootstrapping that very first purebred.
Things to Know
Every tier must be red
Santa Gertrudis is a distinctively red breed, and unlike some breeds where color just routes you to a lower tier, here a non-red animal can't register at all — at any tier. Keep your line red.
The origin ratio has to be exact
Purebred-by-origin means exactly 3/8 Brahman + 5/8 Shorthorn — not close. An animal partway there is a Foundation animal, still building toward the target.
STAR 5 needs a registered Santa Gertrudis parent
The grading ladder (Levels I and II) requires at least one registered Santa Gertrudis parent. A 50% animal with no papered SG parent won't enter STAR 5.
Two foundation breeds, then it runs on itself
You need registered Brahman and Shorthorn to bootstrap the first purebred. After that, the breed grades up on its own Santa Gertrudis percentage and you don't need fresh Brahman/Shorthorn crosses anymore.
It's paper percent, not genetics
Everything keys off the parents' registration papers, not raw genetic makeup. Register your foundation stock first.
Summary
There are no Gen 0 Santa Gertrudis — build them up, and keep everything red. To make your first purebred, cross registered Brahman and Shorthorn through Foundation animals until you hit exactly 3/8 Brahman + 5/8 Shorthorn. After that, grade red cattle up the STAR 5 ladder — 50% (Level I) to 75% (Level II) to 87.5%+ (Purebred) — by breeding back onto purebreds.