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Agouti (Bay/Black)


Description

Bay Horse
Bay Horse

The Agouti gene controls the distribution of black pigment. This pigment can be either uniformly distributed or distributed to "points" of the body (ear rims, lower legs, mane, tail). Agouti has been linked to a deletion of 11 nucleotides in the agouti gene. The 11 nucleotide deletion of this gene is the recessive form of the gene. Only when the agouti gene is homozygous for the deletion (aa) is the black pigment evenly distributed. Heterozygous (Aa) or homozygous for the absence of the 11 nucleotide deletion (AA) results in point distribution of black pigment. Agouti has no effect on homozygous positive red factor (ee) horses for there has to be black pigment present for agouti to have an effect.

 

Why test for Agouti?

There are several reasons an individual might want to test their horse for Agouti. Agouti is not shown physically on red (ee) horses. Therefore, a breeder might want to test a chestnut base horse to see if it is an Agouti carrier. Testing bay horses might be desired to see whether the horse carries one (Aa) or two (AA) copies of the Agouti allele. A homozygous Agouti (AA) horse will always pass Agouti to its offspring whereas a heterozygous (Aa) horse will have a 50% chance of passing on the gene. Another reason to test for Agouti might be if there is some doubt whether a black horse is truly black or a very dark bay. The effects of other genes might also make it hard to tell if Agouti is present or not. This test does not determine if a horse is homozygous for black factor. To determine black homozygosity, a breeder should test for Red Factor. See the Red Factor page for more info.

Agouti Testing

Animal Genetics offers DNA testing and detection of the Agouti bay/black pigment distribution.


Cost

$25.00 US per sample.

Sample Collection

Collect sample by pulling (not cutting) 20-30 mane or tail hairs with roots attached. It is important that you pull the hairs and confirm that the actual root of the hair is being collected. The root contains the genetic material of your horse that is needed for DNA testing. Therefore, cut hairs do not provide an adequate sample of your horse's DNA. Place the collected hairs of each horse in separate zip-lock bags labeling the bags accordingly with the horses name or identification number. Download and complete a submission form for each sample and send along with payment to Animal Genetics for testing.

Results

Results are given using the following symbolic notation:

aa
Only recessive allele detected. Black pigment distributed uniformly. The basic color of the horse will be black in the absence of other color modifying genes.
Aa
Horse tested Heterozygous for Agouti. Black pigment distributed in point pattern. The horse can transmit either A or a to its offspring. The basic color of the horse will be bay or brown unless modified by other color modifying genes.
AA
Only dominant allele detected. Black pigment distributed in point pattern. The horse cannot have black foals regardless of the color of the mate. The basic color of the horse will be bay or brown in the absence of other color modifying genes.

Animal Genetics, Inc.
1336 Timberlane Rd - Tallahassee, FL 32312
Toll Free: 866-922-6436

Copyright © 1995- Animal Genetics, Inc. All rights reserved.

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