This message is from: [EMAIL PROTECTED] (BRIAN C JACOBSEN)
Meredith,
The following information about Fjord coloring is summarized from a paper
by Tor Nestaas who is an official in the Norwegian "Department of
Agriculture" (not exactly what they call it). Mr. Nestaas took his
information from a thesis by the late Johs. Loen and from conversations
with Kari Ann Indrebo, both in Norway.
Fjord coloring is controlled by a number of factors, but three main genes
are responsible:
B - gene for black
A - gene for limitation of black
C - gene for color or dilution of color
Any Fjord that has black coloring (brown dun, grey dun, and white dun)
has a dominant copy of the gene B. Those without black (red and yellow
duns) have a recessive copy of it.
Brown duns and white duns also have a dominant copy of the gene A which
limits the black, so most of these horses do not have as much black or
smoky color as a grey does. Grey duns have a recessive copy of it, so
their black or dark coloring is not as restricted. Some red and yellow
duns have a dominant copy, and some have recessive, but it doesn't matter
because they do not express black because of gene B.
Brown duns, red duns, and some grey duns have only a dominant copy of the
gene C, meaning there is no dilution of their color. Yellow duns, white
duns, and some grey duns have the dilution factor present.
Some practical results of these factors: (some things will be repeated,
but it is presented this way to make it easy to find the results of
breeding your own mare or stallion with the same or other colors):
1. Breeding a BROWN dun to either a BROWN, RED, or CERTAIN GREY duns:
Theoretically, only brown dun, red dun, or grey dun offspring can
result. The diluted colors, yellow dun and white dun, should
not be possible. And any grey dun that resulted would have a
dominant copy of the gene for dilution (C), meaning dilution is not
expressed. (Usually a dominant copy of something means it IS
expressed, but not with dilution). This means that, bred back to brown
duns, red duns, or similar grey duns (no dilution) , those are
still the only colors possible in the offspring (brown, red,
and grey).
How can you tell which greys are dominant for dilution (dilution is
not expressed in offspring) and which are recessive (dilution is
expressed in offspring)? Good question. You can't tell by
looking. Comparing the colors and genetics of the grey horse's
parents and offspring is the only way short of DNA testing (not the DNA
testing the Registry requires - this is much more involved)
- Breeding BROWN dun to a YELLOW, WHITE, or GREY WHO HAS THE
DILUTION FACTOR: Any color could result except albino.
*NOTE* there is one genotype (combination of genes) of brown dun
that, when bred with other brown dun or red duns, only results in
brown dun. If you like brown dun and don't particularly care for
red dun, having a horse like this would be a bonus. Note, however,
that it would take many breedings to be sure this was the case with
your horse; Having a brown dun foal 3 out of 3 times is not nearly
enough, especially if the horse has never been bred to a red dun.
2.. Breeding RED dun to RED dun: Always results in a red dun.
-Breeding RED dun to YELLOW dun: Results in either red or yellow
dun only.
-Breeding a RED to a BROWN or GRAY WITHOUT DILUTION FACTOR: Same
as #1.
-Breeding a RED to a WHITE OR GRAY WITH DILUTION FACTOR: Any color
is possible.
3. Breeding a GRAY WITHOUT THE DILUTION FACTOR to a BROWN, RED, OR
ANOTHER GRAY WITHOUT THE DILUTION FACTOR: Can give brown, red or
grey (also without the dilution factor).
-Breeding a GREY WITHOUT THE DILUTION FACTOR to a YELLOW OR WHITE
DUN: Can result in any color.
- Breeding a GREY WITH THE DILUTION FACTOR to ANY OTHER COLOR: Can
result in any color.
*NOTE* There is one genotype (combination of genes) of grey duns
that, when bred with another grey, can only produce grey
horses. If you are lucky enough to have a Fjord like that, we
have some grey dun breeders in the Registry who would love to
talk to you. Again, getting a grey twice out of two breedings, for
example, is not good enough to say for sure that this is the case
with your horse.
4. Breeding YELLOW or WHITE duns to BROWN, RED, AND GRAYS WITHOUT
THE DILUTION FACTOR: Can result in any color, but not albino.
-Breeding YELLOW or WHITE duns to YELLOW, WHITE, AND GRAYS WITH
THE DILUTION FACTOR: Can produce any of the colors, including
ALBINO. Note, however, this is not a true albino because
they have blue eyes. They are instead, a very white horse.
(Not recommended for areas of the world that get a lot of snow :
)
Remember, there are several different possibilities of genotypes for each
color. It is a complex interaction, not a simple one. As Tor Nestaas
says, "One cannot decide from the looks of a horse what kind of genotype
of color it has. By studying the pedigree and the colours of his
ancestors, one can get some certainty of what genotype a certain horse
may have. But only by noticing what colour the offspring[s] are, one can
be certain of what kind of colour genotype the horse has." And I might
add, "it often takes alot of offspring, produced by breedings with the
same and different-colored Fjords, to really be sure."
Brian Jacobsen, DVM
Norwegian Fjordhest Ranch
Salisbury, North Carolina
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