Tweed: Genetics & History in New Zealand
The rare Tweed breed genetics and history is fascinating. The Tweed genes arrived with cavy judge Christa Krey first import of satin cavies to New Zealand around 1985, though hidden as these were solid gold in colour.
After mating with other colours, the gene appeared in chocolate-gold-white tricolours, at this time it seemed to only affect the chocolate colour, not the gold or white.
It seemed to be a sub-gene of chocolate (NOT a lethal gene like Roan and Dalmatian), expressing itself as an even mixture of chocolate and white hair. Not like the grizzling in some chocolate cavies, which usually disappears when the cavy grows. However, this gene did actually express itself better as the cavy grew and did not disappear over time. Christa found it rather attractive, and decided to try a cavy in this, in an overall uniform version.
The Tweed gene is recessive. Breeding Tweed to Tweed produces 100% Tweed.
When breeding Tweed to Tweed carrier this usually give 50% Tweed and 50% Tweed carriers. Lastly, carrier to carrier gives 50% carriers, 25% Chocolate and 25% Tweed.
A Tweed carrier is a poor-quality Tweed with faults, for example gold or white patches.
Note: Gold coloured Tweed have recently been created overseas. Maybe one day in NZ.
The Tweed Cavy Genetic Formula
The Tweed pedigree guinea pig is a beautiful pattern variety that relies on a specific base combination to properly showcase its heathered, flecked ticking.
A_ B_ C_ E_ P_ ss + [Twd_]
Locus-by-Locus Breakdown for the Tweed:
A_ (Agouti Base): The dominant Agouti gene is required to establish the base ticking pattern across the coat.
B_ (Black/Brown Locus): Ensures the dark parts of the pattern remain a deep black or dark chocolate, depending on the specific breed line.
C_ (Full Color Locus): Preserves full colour saturation so the ticking remains distinct and highly visible against the background.
E_ (Extension Locus): Extends the base colour uniformly over the entire body, preventing tortoiseshell breaking.
P_ (Dark Eyes): Ensures bold, dark eyes to match the deep ticking of the coat.
ss (Non-Spotting): Solid base that completely avoids random white patches which would destroy the symmetry of the flecked pattern.
[Twd_] (The Tweed Modifier): The specific polygenic modifier complex or partial-dominant trait that breaks up standard ticking into a distinct, mottled heathered appearance.
The defining characteristic of the Tweed cavy is the [Twd_] Tweed Modifier. Rather than introducing a new colour, this specific modifier alters the expression of the dominant Agouti gene. By breaking up the standard pigment banding on each hair shaft, it produces a beautifully blended, heathered, and flecked phenotype that is completely unique to the variety.
Breeding Tip: For maximum efficiency and show-quality results, always prioritize Tweed-to-Tweed pairings to guarantee 100% Tweed litters. Keep a strict eye out for coat density and ensure that the signature dark mask remains prominent against the silvered body hairs.
