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Much research and literature has been
written on the subject of equine color genetics. This small
dissertation is not
meant to be a scientific paper on the subject.
All horses tend to have either black or
red as a base coat.
Black is a basic color for horses .Black is also a
recessive gene which means that the gene can be overwritten by
any number of other genetic factors. The best indicator of the
color black is the lower leg. The black color,
considered a base color, is caused by several alleles. Some horses may
have the black gene and may actually look more non-black.
However, genetically they are, indeed,
black.
Black horses have black points -
primarily black manes and tails. Other points are present but
these points are the most reliable. Most black horses and all
horses in general fade in the sunlight. As a result the horse
can actually look brown red or grey. If exposed to sunlight
for a period of time, the average black horse will turn to a
brownish black or reddish horse in color on the mane and
points. However, when the sun is not so intense the black
color re-emerges. The color black is actually protective since
black horses do not tend to get skin cancers or tumors
(melanomas) as do grey horses. In previous times black and
darker colors were considered to be hardier
animals.
Dominant
genes are described with
capital letters such as A, B, C, D, or E and recessive genes are
described with small letters (a,b,c,d,e). Theoretically, a
dominant gene prevails. However, this is theoretical and not
absolute. The most important genes will be considered here.
All genes are operational at all times. The total picture of
genetic expression is called phenotypye. In other words, all
these genes are working at the same time. A homozygous gene of
one type does not guarantee a black horse when breeding. See
below.
There are five basic genes
related to color :
A-the Agouti gene which allows black to
be seen when recessive(aa)
B-black or brown
gene
C-colored
restriction
D-dense color or
dilution
E-the extension gene for color from the
base of the hair to the tip of the hair
The A gene: The letter A stands for Agouti. When
recessive the
non- Agouti gene (aa) causes the hair color to be black
and pigmented from base to tip. This gene must be present for
the color black to show or else the color black will be hidden
by other colors. We don’t want a dominant A gene as the hair
pigment would be spotty.
The B gene: This controls the color black but is
not the only gene affecting the color black. The gene
depending upon its expression in the individual horse will
create either black or bay.
The C gene: This gene causes color restriction i.e.
the areas restricted to color or by color-slightly confusing
without the remainder of the information below. It determines
how and much color is expressed or not. Simply put, the gene
expression will lighten any color that is the base
color.
The D gene: This gene causes color density or
dilution. Dominance or recessiveness of this gene will create
a deep or diluted coloration. Basically, a dun horse is
created if expressed
The E gene: “E” stands for extension for its
effect on the eumelanin or black pigment of the horse. Large
letter E equals a dominant gene while a small letter equals a
recessive gene. Therefore, we can have a EE black which is
homozygous or an Ee black which is heterozygous black. Both
will show black as the color if combined with the Agouti aa
gene. Let me state that again-both homozygous and heterozygous
expression of the E gene will produce a black horse. You need
the non Aguoti gene to express black. Homozygous is not enough
to produce black by itself.
Horses that are homozygous for black may
be homozygous dominant or recessive. One homozygous
combination of either recessive or dominant genes does not
control the final outcome of a breeding. Many potential
breeders look only to the stallion genetics. The genetics of
the mare must be considered also. Black bred with black will
give a black foal provided at least one parent is dominant E
in one gene only.
Alleles are “an alternative form of a gene that
can occupy a particular chromosomal locus” or location.
Alleles are basically one half of a gene. As a result there
are usually two alleles on each chromosome. If a horse has two
alleles on the chromosome that horse is considered “homozygous”- or
possessing a pair of alleles for that trait. If a horse has
only one allele then that horse is considered “heterozygous” -or
possessing only a single allele. Not every allele “counts” or
is expressed as the terminology is used. If you have the
allele you still must have the genotype or
the entire genetic constitution to cause black. Some
alleles are recessive and some are dominant.
There are factors which modify or change the
color black. Indeed, there are several shades of
black. There is a jet black, raven black, plain black, summer
black and entrepelado (essentially a roan black). Jet black
horses never fade in the summer and others become a flatter
color but are still black The color black can be a soft
velvety black to a flat black.
The Spanish have several terms for the color
black.
Jet black is called negro azabache with a
black color similar to a shining mineral.
Coal black is called negro morcillo(or morcilla if a mare)
which is a less intense black color than jet black. Many claim
that it is similar to a ripe blackberry.
Tarry or ill-dyed black(negro peceño or mal teñido) have a
color of pitch and/reddish highlights.
Roan black or entrepelado
There is an ancient Spanish proverb that
states that “A whole coloured black is sought by many and
found by few.” Therefore, it is normal to find some head
markings on black horses.
The best and easiest way to get black is
to breed to or to buy a black horse. Contrary to statements on
some websites that the color black takes years to manifest
itself, our experience is that the color becomes visible and
known within six months, if not sooner. You don’t have to wait
years to have a black horse.
Call Poplar Ridge Andalusians
for your black
Andalusian -the Pura Raza Espanola (PRE) dream horse! We have
all types of black and some bay horses. Black is magnificent,
elegant and beautiful! Our horses are all healthy and of
exceptional quality and breeding. Call us and see for
yourself! | 
