Rabbit Coat Color Genetics Calculator
Multi-locus Punnett square simulator evaluating independent assortment across the five classical color loci to forecast kit coat phenotypes.
Litter Phenotype Probabilities
The 5 Classical Loci & Epistatic Dominance Hierarchies
Domestic rabbit coat coloration is governed by classical Mendelian inheritance first mapped systematically by W.E. Castle at Harvard University in 1930. Five primary autosomal loci control the synthesis and spatial deposition of eumelanin (black/brown) and phaeomelanin (yellow/red) pigments along individual hair shafts.
| Locus | Biological Function | Dominance Hierarchy | Primary Phenotypes |
|---|---|---|---|
| A (Agouti) | Hair shaft pigment banding | A > at > a | Agouti (A), Tan/Otter (at), Self solid (a) |
| B (Black/Brown) | Eumelanin oxidation state | B > b | Black (B), Chocolate/Brown (b) |
| C (Color Series) | Tyrosinase enzyme activity | C > cchd > cchl > ch > c | Full color (C), Chinchilla (cchd), Sable (cchl), Himalayan (ch), Albino (c) |
| D (Dilution) | Pigment clump density | D > d | Dense (D), Dilute Blue/Lilac (d) |
| E (Extension) | Eumelanin distribution | Es > E > ej > e | Steel (Es), Normal (E), Harlequin (ej), Non-extension Orange/Tort (e) |
Avoiding Lethal Alleles: The Charlie Megacolon Risk
In addition to the five primary color loci, pattern modifiers such as the English spotting gene (En) introduce severe health considerations. The En allele exhibits incomplete dominance. Heterozygous rabbits (En/en) display the classic show-standard broken coat pattern with 50% white and 50% color distribution.
When two broken rabbits are crossed, 25% of offspring inherit two dominant copies (En/En). These homozygous 'Charlie' kits suffer from congenital aganglionic megacolon due to defective neural crest migration during embryogenesis, leading to permanent digestive failure and premature death. Professional rabbitries prevent Charlies by crossing broken animals exclusively with solid self mates (En/en x en/en).
Frequently Asked Questions About Rabbit Color Genetics
01What are the five primary gene loci governing rabbit coat colors?
The five primary coat color loci in domestic rabbits are A (Agouti/Pattern), B (Black/Chocolate), C (Color/Albino series), D (Density/Dilution), and E (Extension of dark pigment). Together with specialty modifiers, these five loci produce all recognized ARBA show varieties.
02How does the albino (REW) gene override other color loci?
The albino allele (c) on the C locus is completely epistatic when homozygous recessive (c/c). It disables the tyrosinase enzyme required for melanin synthesis, resulting in a Red-Eyed White (REW) rabbit with zero pigmentation, regardless of which dominant genes exist at the A, B, D, or E loci.
03What is the genetic difference between a Black rabbit and a Blue rabbit?
A Black rabbit carries at least one dominant dense allele at the D locus (D/D or D/d), causing eumelanin granules to pack tightly in the hair shaft. A Blue rabbit is homozygous recessive for dilution (d/d), causing pigment granules to clump irregularly, refracting light as slate gray.
04What coat colors result from crossing a Castor buck with a Self Black doe?
A Castor buck (A/A B/B C/C D/D E/E) crossed with a true-breeding Self Black doe (a/a B/B C/C D/D E/E) will produce 100% Castor agouti kits in the F1 generation, all carrying the recessive self allele (A/a). Breeding two F1 Castors yields a 3:1 phenotypic ratio of Castor to Black kits.
05What is the lethal 'Charlie' gene in broken pattern breeding?
The broken spotting locus (En) exhibits incomplete dominance. Crossing two broken rabbits (En/en x En/en) produces 25% homozygous broken (En/En) offspring, colloquially termed 'Charlies' (less than 10% color). Charlies suffer from hereditary congenital megacolon, causing fatal cecal impaction.
06How does the Chinchilla gene affect rabbit pigmentation?
The chinchilla allele (cchd) removes phaeomelanin (yellow and red pigment) from the hair shaft while leaving black eumelanin intact. On an agouti base (A_ B_ cchd_ D_ E_), this converts the warm golden-brown agouti bands into pure silver-white and pearl, producing the Standard Chinchilla variety.