So as covered in the Genotype discussion (click on Genotypes if you missed it), there are 5 basic sets of genes that establish coat color in a rabbit A-E series. (Vienna, fuzzy, and other genes will be discussed separate.) Remember that the coat color is determined by the dominate gene out of each pair and the recessive gene is shown as “_” until one can determine what recessive gene they are carrying. Example: Chestnut A_B_C_D_E_. None of the 2nd pair of genes in a chestnut matter because all of the 5 gene series are the dominate genes and cover up everything else.
The first grouping is called the A-series and includes three genes that create patterning on a rabbit. Each rabbit inherits one A-series from each parent and that pairing will determine the following:
Agouti Pattern “A”
The most dominate of the A-series is the Agouti gene represented as “A”. When a rabbit carries this gene it is dominate over any other A-series gene that rabbit may have inherited. (Remember they carry genes in pairs, one from each parent). This gene causes a ticking pattern like you would see in a wild rabbit in your back yard. This pattern causes rings of color on the hair shaft, light markings around the chin, belly, underside of the tail, inside of ears and the inside of their legs. This grouping consists of such colors as chestnut and orange. Any Agouti colored rabbit can recessively carry and hide the otter and self-patterns which are recessive to Agouti.
A chestnut colored rabbit could carry all of these combinations in the A-series, but will look exactly the same:
Tan Pattern “at”
The second most dominate gene in the A-series is the Tan Pattern “at” which is most recognized as the otter patterning. They are solid colored on the back and most of the head, with bellies, ears, and underside being a lighter color. The hair shafts would not have ringed or ticket patterning. This gene is recessive to “A” Agouti and therefore any Tan pattern rabbit does not carry agouti. It is however dominate to Self “a”.
Black Otter can be the following:
Self Pattern “a”
Lastly is the most recessive gene, the self-gene. This produces all the blacks, blues, torts, and many other solid colors. A self-rabbit cannot carry the Agouti or the Tan gene. If you breed a black rabbit to a blue rabbit you cannot get an otter or chestnut, it’s just not possible.
Tort: aaB_C_D_ee and no other possible A-series genes
NOTE: The above A-series is mostly standard, but patterning and color can be affected by both the C-series (shaded) and the E-series (extension). This is why a tort with self “aa” is not a solid color or a Harlequin A_B_C_D_ej_ doesn’t look like a chestnut. Gotta love all these genes, right?