HOW TO MAKE A CHOCOLATE RABBIT Basics of the dominant/recessive relationship

A review of basic genetic terms  Rabbit colors, just like other traits (size, fur structures, eye color, toenail color, and hundreds of others) are inherited from the rabbit's parents: called the Sire and Dam.

The recipe for chocolate rabbits The nucleus (center) of every cell (muscle, blood, skin, hair, etc…) contains all the information that determines the genotype of the rabbit. The genotype is similar to a set of instructions. It's just like a recipe so we can say the recipe is carried in the genes, which are certain spots on the chromosomes, in the nucleus of each cell.

Major Ingredients  Rabbits have 22 pairs of chromosomes. Each chromosome has lots and lots of genes-hundreds, maybe thousands. Every cell of every part of the rabbit has 22 pairs of chromosomes.  Out of the thousands of genes in a rabbit, the major genes for colors have been identified by scientists. These are the dominant genes  A for agouti pattern  B for black  C for having color  D for density of color  E for extension of color along the hair shaft.

The Secret Ingredient  Very rarely, a gene changes, or mutates, for some unknown reason, and it will take a different form. Another form of a gene is called an allele. A rabbit with a mutated gene can pass this new allele to its offspring.  The scientists have identified recessive alleles of the 5 dominant color genes (A, B, C, D, E) and have given them lower-case letters to serve as their genetic codes (a, b, c, d, e).  a for absence of agouti pattern, making it solid  b for brown (chocolate, actually)  c for no color (albino)  d for dilute  e for non-extension of color on the hair shaft.

Step one  When a male rabbit (buck) and a female rabbit (doe) are mated, the buck provides the sperm cell, with 22 single chromosomes, to combine with an egg cell from the doe, with 22 single chromosomes to make 22 pairs for the first cell of the developing new bunny.  The baby bunny gets half of each of its chromosome pairs from the sire (father) and half from the dam (mother). SO, since the genes are on the chromosomes, it's getting half of it's genes from the sire and half from the dam.

How much of each ingredient?  Since every bunny inherits half of each gene pair from its sire and half from its dam, it might inherit an original gene form (capital letter) from one parent, but a different form of the same gene (lower-case letter) from the other parent.  We want a chocolate colored rabbit, so the genes we need from each parent are:  a, so it’s a solid colored rabbit through all of its fur.  b, so it gives us the chocolate color instead of black.

Results are not always what we want, so we may have to try again  Capital letter codes for the dominant genes and they dominate;  what they say goes!  Even when there is one dominant gene and one recessive gene in a gene pair, the color will be what the dominant gene says.  This is the dominant/recessive relationship.

B series of rabbit coat color BB dominant black bb recessive brown (chocolate)

The possibilities