by Liberty Wallace

Created on: March 02, 2007   Last Updated: June 25, 2009

There is nothing mysterious or confusing about color genetics in horses. Genetics are genetics. They are the same in all species. Every offspring in the world receives half of their genetic make-up from each parent. Fifty percent. Horses are no different.

"Homozygous" is a term used to describe an animal who will always produce a certain dominant gene in their offspring. A homozygous horse carries two copies of the same gene, and had to receive one of those genes from each parent. A solid mare bred to a pinto stallion could produce a pinto, but could not produce a homozygous pinto, as the mare had no pinto gene to contribute. A stallion that is homozygous pinto will always produce a pinto foal regardless of the mare he is bred to, but that resulting foal would not by homozygous itself unless the mare is also pinto. And vice versa, a homozygous pinto mare will always produce a pinto foal regardless of the stallion, but must be bred to another pinto for there to be any chance of producing a homozygous pinto foal.

A horse can be homozygous for patterns (such as pinto) or for colors (such as black), or even both at the same time. Certain colors are known to be homozygous without any need for DNA testing. For instance, the "cremello" coloring in horses, which was once incorrectly believed to be an albino, is the homozygous producer of palominos and buckskins. A cremello has two copies of what is called the "cream" gene, so will always contribute one of those cream genes to it's foals. Palominos and buckskins are horses that carry one cream gene, so if your goal is to always produce palomino foals, you would want to use a cremello mare or stallion in your breeding. A palomino or buckskin still has a 50% chance of contributing their one cream gene to a foal, but many color breeders prefer the guaranteed results a cremello can provide.

Breeding horses for certain colors is always a gamble, but the risks can be minimized by using at least one parent who is homozygous for the color or pattern you are trying to produce.

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