UC Davis School of Veterinary Medicine Veterinary Genetics Laboratory
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Agouti (Bay/Black)

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The Agouti gene controls the distribution of black pigment. The dominant allele A restricts black pigment to the points of the horse (mane, tail, lower legs and ear rims), as seen, for example, in bays and buckskins. The recessive allele a uniformly distributes black pigment over the entire body.

Breeders interested in producing black horses need to have breeding stock carrying the a allele, in addition to the E allele of the Extension gene. Using results from the red factor and agouti tests, click here for a table of breeding schemes to produce black animals.

Agouti results are reported as:

A/A

2 copies of agouti present. If present, black pigment is restricted to the points.
A/a 1 copy of agouti. If present, black pigment is restricted to the points.
a/a If present, black pigment is distributed uniformly over the body.
 
Veterinary Genetics Laboratory, Tel 530-752-2211, Email VGL