With the world of horse breeding becoming so competitive, some breeders have decided to publish color producing percentages of their stallions.  It has become common place to see phrases such as "80% Color Producer" and "100% Dun Producer".  What do those percentages mean?  This article should help clear up some of the main questions surrounding color production.  It should be taken in the context of registered quarter horses, but in many cases, may be applied towards all breeds.

There are 16 colors in the quarter horse registry (AQHA).  They are;

*Perlino and Cremello were added to the list of acceptable colors in 2003.

Color production is generally considered reproduction of the stallion's color or color characteristics such as "dilution", "roaning" or "dun factor".  Some stallion owners have taken it a step further and count color producing as anything that is not bay, sorrel or chestnut.  Is this really color production?

Most scientists and horse genetic scholars believe coat colors are controlled by the following six genes.  They may be present in dominant (capital letter) or recessive (lower case) form.  A gene is made up of two alleles, one inherited from each parent.

• E - The red factor gene (controls point color.  Dominant Es result in black points, 2 recessive e as red points.)

• A - The Agouti gene (controls body color if a dominant E is present)

• C - The creme gene (dilutes body color as seen in palominos and buckskins)

• D - The dun gene (adds dun factor to the horses body as commonly seen in grullos, red duns and regular duns)

• G - The gray gene (modifies the base coat to a gray color over time)

• R - The roan gene (modifies the base coat to a roan coat) 

It hasn't been fully agreed by scientists on how the brown, liver chestnut, champagne, lobo grullo, sabino, rabicino and a few other unique colors are created.  Some believe they are a result of gene modifiers while others believe they are an entirely separate gene.  Different shades of color can often be attributed to particular families much like hair color in people.  For purposes of this article, we will concentrate on specific genes identified above, and in particular, the homozygous red factor EE, or commonly known as "homozygous black".

Homozygous Black Example (EE)

A horse may carry heterozygous (one dominant, one recessive) alleles or homozygous (both dominant or both recessive) alleles for a gene.  For example, let's evaluate the red factor gene E.  Sorrel horses are homozygous for the E gene and the E values are "ee".   Black pointed horses may be homozygous "EE" or heterozygous "Ee" for the E gene.  Horses with red pointed parents like sorrels or palominos will always pass a recessive "e" to their offspring.  If the resulting foal has black points, it inherited the dominant "E" from the other parent.  That is why sorrels bred together only produce sorrels or chestnuts and no other color.  Horses may be tested for red factor at UC Davis.  If a horse has black points and one parent had red points, there is NO NEED to test the horse for red factor because it is automatically typed "Ee".  If both parents were black pointed, the resulting black pointed foal has at least a 1 in 3 chance of being homozygous black "EE" .  Many people incorrectly say the colt has a 1 in 4 chance of being "EE".  The reason?  Based on physical inspection, the "ee" result can be ruled out because the foal exhibits black points.   BEFORE the point color on the foal is known, their is at least a 1 in 4 chance a colt will be homozygous black.  Advertisements that state "this foal is likely homozygous black" are false advertising.   It is either homozygous black-guaranteed, has a 50% chance of being homozygous, or it is unlikely to be homozygous black.

Let's review the following chart and assume the resulting foal has black points:

As you can see, at best, the resulting black pointed foal either is guaranteed to be homozygous black if both parents are homozygous black, has a 50% chance of being homozygous black if 1 parent is homozygous black, or is unlikely of being homozygous black (1 in 3) if both parents have heterozygous black points.

To expand further, a parent always contributes 50% or 100% of a foal's color.  If the parent is EE, or homozygous black, all resulting foals will have black points.  If the parent is heterozygous black Ee, the resulting foal may, or may not have black points depending on the color of the other parent and which allele each parent throws.  So, if a horse is NOT HOMOZYGOUS, color percentages offer NO GUARANTEES.  If a horse produces more than 50% of it's color characteristics, it is either homozygous and always reproduces the characteristic, or dependent on the color and genes of the other horse.  Two parents that carry the same characteristics such as black points create at least a 75% chance that the resulting foal will have black points.  However, there are no guarantees if neither horse is EE. 

So, what does all this mean?  If a horse is advertised as 100% color producer, a person should ask for a definition of "color".   A horse can be homozygous for any of the above genes so some horses are 100% black point, dun factor, gray or roan producers, etc.  However, aside from red factor, the only test available is for the creme gene on a limited basis, and usually not required for horses because homozygous creme carriers are usually identified by visual inspection.

If a horse isn't homozygous, there are three possibilities for a higher desired color production;

1. It is mere a coincidence

2. The stallion owner is counting multiple genes for percentages (like red factor, dun and creme)

3. The color of the other parent also exhibits the same characteristics

If a horse is advertised as a "high color producer" and isn't homozygous for particular genes, the statement holds little meaning unless the goal is to produce a non-sorrel foal.  Even then, the horse should carry multiple heterozygous genes like black points (E), dun factor (D) and the Creme (Ccr).  Every dilution, dominant E, gray or roan allele that a horse carries decreases the likelihood that the foal produced will be sorrel.

The point should also be stressed that color is just one of many check points to consider when breeding.  Pedigree, Conformation and Temperament should also weigh heavily in decision making.

Questions to ask stallion breeders that are advertising high color percentages:

1. How many foals has the horse sired?  If the amount is under 20 foals, the result set is too small to be valid.

2. What is their definition of "color"?

3. What color mares have they bred?

It should display:  Getting Informed...About the Myths of Color Producing Percentages by Kristy Enloe

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