Contrary to what some others are saying, there is a breed of cattle called Black Herefords. They have their own registry, a separate entity from the AHA, with their own rules for entry into the registry. Black Angus cattle were initially used to fix the black color and now a breeding up process is occurring where they are becoming more and more Hereford in percentage. A "purebred" Black Hereford is at least 7/8ths Hereford blood and black in color. See the rules below taken from the American Black hereford Association website at:
http://blackhereford.com/
RULE 2.2 Eligibility for Registration
Black Hereford animals of any age for which application for registration is made may be registered
with the Association upon proof of compliance with the following requirements:
A. The animal must be a Black Hereford, as determined under the Rules of the
Association.
1. Therefore, a bull or cow must EITHER:
a.) Have an ABHA registered sire and a American Hereford
Association registered dam which is free of genetic defects.
OR
b.) Have both ABHA registered sire and dam.
OR
c.) Be the product of a paring described in a.) which was not eligable
to register due to hair color and an ABHA registered sire.
OR
d.) Be an American Hereford Association sire approved for
admission by a 2/3 vote of the ABHA pursuant to Article II of the
By-Laws. OR
e.) Be the product of an ABHA sire and a F1 dam whose parentage
is registered and free of genetic defects in the American Angus
Association and the American Hereford Association.
2. A bull must have two, well-descended, testicles in order to be eligible for
acceptance into the Registry.
3. A bull, cow or steer must have black hair color.
B. Percentage Bloodlines. All bulls, females and steers for which application for
registration is made shall be classified as 62.5% or greater registered Hereford, be
black in color, and must be sired by a bull registered in the ABHA.
C. Purebred Bloodlines. Bulls and cows shall be classified as a purebred Black
Hereford if they are 87.5% hereford and black in color