Chestnut Agouti Rabbit Color Genetics: 5 Fun Facts

Last Updated on December 18, 2022 by Ellyn Eddy

The study of coat color genetics has taken the rabbit world by a storm.  Breeders remain extremely interested in this important subject.

Not only do you need to know color genetics to be able to choose your breeding pairs wisely, but the study is fascinating in itself.  Here five fun facts that you might not have heard before about an important rabbit color.

1. Chestnut is the Wild Color.

The color we call “chestnut agouti” is the original rabbit color.  It shows the “normal” gene in every category.  As you may notice, wild rabbits appear chestnut agouti.

Different rabbit breeds call this color by many different names (Chestnut, chestnut agouti, sandy, copper, brown, castor) and it looks very different on different fur types.

Brown silver show rabbit
Brown Silver. A chestnut-based color.

2. All Other Rabbit Colors are Mutants.

Every other color results from a mutation of one of the genes that makes chestnut agouti.  A mutation happens when some genetic information is lost in the process of transferring a gene from a parent to its offspring.

As a result, almost all other colors are less dominant than chestnut agouti.  If you breed a pure chestnut agouti to almost any other color, the resulting babies will be 100% chestnut agouti.

3. Chestnut Agouti shows off both black and yellow pigments.

Chestnut agouti shows a beautiful blend of pigments.  If you look at a chestnut, you’ll see a brilliant blend of black and yellow pigments.  The top of the rabbit looks brindled with the two colors, and if you blow into the coat, you’ll see black and red/orange form concentric rings on the hair shaft.

All recessive mutations of the chestnut genes limit this pattern, either by reducing the color intensity (so the black hairs would become blue or chocolate) or by preventing the two pigments from interacting properly.

(For example, a solid black rabbit has the potential to produce yellow pigments, but it doesn’t because the self pattern allele isn’t giving the yellow pigment a place to show up.)

Castor Mini Rex Rabbit
Castor-colored Mini Rex

4. Chestnut is made by a dominant allele on each of the ABCDE loci.

Chestnut shows the normal dominant allele in every main category.  So a pure chestnut – one that didn’t carry any other colors – would have the genotype AA BB CC DD EE.  A rabbit that had the most recessive gene in every category – the genotype aa bb cc dd ee –  would be albino.  Another highly recessive color is lilac tortoise – the genotype aa bb CC dd ee.

5. But it doesn’t include every *most* dominant rabbit color allele.

There are a couple mutations that produce a color pattern that’s actually more dominant than AA BB CC DD EE. 

These are in the “E” series, and the names of them are Steel (Es) and Dominant Black (Ed).  The steel gene will cause the black pigment to over-produce, so it covers up some of the orange pigment in a chestnut, and only lets the light tips of the hairs show.

You can see that illustrated in the picture below.

Bonus fact:  If you enjoyed this article, you can learn more about rabbit color genetics through the book, “About Bunny Colors” from Rabbit Smarties.  This guide is written in simple language (no, it really is!) so that any rabbit breeder can quickly learn how to use color genetics in their breeding.  It incorporates advice from many rabbit raising experts, including ARBA judges and national-winning breeders.