This page contains the fundamental principles of the inheritance of
color in Dexter cattle. These principles are stated in the form of
ten basic concepts and are presented in logical sequence.
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1.
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Dexter cattle occur in three distinct colors: black, red, and dun. Two pairs of genes that are located on separate chromosomes control
these colors.
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2. |
Black and red is one pair of alternative colors. In Dexter cattle,
there are two different red genes. The two red genes are
alternatives to each other, and they are not visually
distinguishable. However, they are distinguishable by a DNA test. Both red genes are recessive to their black alternative. This means
that every red Dexter contains two red genes, one inherited from its
sire and one inherited from its dam.
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3. |
Black and dun is another pair of alternative colors. The dun color
in Dexters is due to a brown mutation, and it is recessive to its
black alternative. This means that every dun Dexter contains two dun
genes, one inherited from its sire and one inherited from its dam.
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4. |
Two black Dexters can produce black, red, or dun calves. In order
for two black parents to produce a red calf, each parent must carry
a hidden red gene. In order for two black parents to produce a dun
calf, each parent must carry a hidden dun gene.
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5. |
In Dexter cattle red is the only color that breeds true. Two red Dexters can produce only red calves even if each parent carries a
hidden dun gene. A Dexter that contains two red genes and two dun
genes is red in appearance.
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6. |
If a red Dexter that has two dun genes is crossed with a dun Dexter
that does not carry a red gene, the result will be a dun calf. Each
dun calf resulting from this cross will carry a hidden red gene.
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7. |
Two dun Dexters can produce dun or red calves. In order for two dun
parents to produce a red calf, each parent must carry a hidden red
gene. Every red calf that is produced by two dun parents will have
two dun genes. (See #5 and #6 above.)
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8. |
When a red Dexter that doesn’t carry a dun gene is crossed with a
dun Dexter that doesn’t carry a red gene, the result will be a black
calf. Each black calf resulting from this cross will carry a hidden
red gene and a hidden dun gene.
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9. |
A colored Dexter calf must be red if its sire or dam is known not to
carry dun. Conversely, a colored Dexter calf must be dun if its sire
or dam is known not to carry red.
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10. |
Additional genes, independent of the genes for the basic colors, may
be present in an animal’s genotype and may modify the appearance of
the animal. Such genes include but are not limited to those which
are responsible for brindling, black noses in reds, black shading in
reds, and the shade of color of reds and duns. Modifier genes do not
alter the principles contained in the preceding nine concepts. |
