Why should I genotype my rabbits? The answer to this question is as diverse as the people who ask it. You should genotype your rabbits if you raise a breed with more than one color variety. The more varieties your breed has, the more important genotyping becomes. If you sell pedigreed breeding stock, show your rabbits, sell fur or wool, or even if your desire is to produce a variety of colors for pets, you need to genotype. With a genotyped herd, you can plan breedings to meet your objectives, whatever they might be. You can also avoid costly mistakes, such as producing ìunrecognized colors you cannot show or sell as show stock. If you market fur or angora wool, you cannot afford to be without genotyping, as you will need to produce colors which are specified by your customers. In order to make a sale, you must give the customers what they want or they will find someone else who can.
These instructions will give you the ability to genotype your rabbit herd. By reviewing the basic principles and following the procedure step-by-step, you will be able to determine a large proportion of the genes animals in your herd carry. This procedure will be especially useful for following elusive recessive alleles, and will give you the edge in producing any color you desire. Donít leave your breeding up to chance any longer. Donít let opening the nest box for the first peek at each new litter be a complete surprise, or shock, depending upon the outcome. Genotyping is a valuable tool which should be used by every rabbit raiser.
The glossary of terms which follows contains the terms used in instructions and descriptions. Appendix B lists the phenotypes and genotypes of quite a few of the most common angora colors. I will be adding to these lists as I have the time, hopefully soon.
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This article to complicated? Want to skip the hassle? Click here to skip to the direct DNA tests, now available for Rabbits!!!!!!Gene Set: The set of all of the genes that affect rabbit color.
Subset: A group of genes that are related by being carried on the same chromosome and affecting the same trait, meaning that these differences are mutually exclusive, such as there being no such thing as a self agouti, blue black, chocolate black, etc.
Allele: A certain gene that imparts one modification. Its Alleles are other genes that affect the color in a similar way, but only one expression will be visible.
Dominant: A gene that imparts its influence strongly, as the name would imply. This gene can "cover" the actions of other alleles in its subset that are present in a given animal.
Recessive: A gene that changes the color, but can be covered by the presence of a more dominant allele.
Phenotype: The physical characteristics displayed by an animal.
Genotype: The genetic background producing the visible color.
Homozygous: A term that describes the condition of an animal having two of the same alleles for a given modification.
Heterozygous: A term that describes the condition of an animal having two of different alleles for a given modification.
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The genetic principles of rabbit coat color genetics are similar to
those found in all mammals. In any subset, only two genes may be
present in an individual rabbit, but many alleles may be present in a
herd of rabbits. What follows is the list of the five subsets
commonly affecting coat color in rabbits, and each allele I have
found to be a valid, distinct allele is listed under the appropriate
subset. The letter used to denote each allele is derived from the
subset into which they are grouped, and the subsets are arranged
alphabetically by a word describing how the color is affected.
Realize that these are just arbitrary groupings and follow standardized nomenclature for all mammalian species. The alleles are listed in order of decreasing dominance. For example, in subset C, cw is dominant to cs, ch and c, but is recessive to C.
|
Subset A: |
Agouti Pattern |
|
|
A |
Agouti pattern: |
Banded hair shaft, light belly and underside of tail. |
|
at |
Tan pattern: |
No banding on hair shaft, light belly and underside of tail. |
|
a |
Solid, or Self pattern: |
No banding on hair shaft or light markings. |
|
Subset B: |
Black/Brown |
|
|
B |
Black: |
Any animal showing black or blue coloration. |
|
b |
Chocolate: |
Any animal showing chocolate or lilac coloration. |
|
Subset C: |
Color Expression |
|
|
C |
Full surface and tan. |
|
|
cw |
Full surface |
tan converted to silvery white. |
|
cs |
Shaded surface |
tan converted to silvery white. |
|
ch |
Color confined to points, no tan: |
Temperature sensitive. |
|
c |
No color expression: |
Ruby eye white. |
|
Subset D: |
Density of Surface Color |
|
|
D |
Full density: |
Surface color displays full intensity. |
|
d |
Dilute: |
Surface color displays reduced intensity. |
|
Subset E: |
Extension of Surface Color |
|
|
ES |
Extension of dark color |
(produces steel with A-, variable with aa and/or e). |
|
Ej |
Japanese: |
Surface color conjugated to patches or streaks. |
|
E |
Normal extension: |
Color evenly distributed on hair shaft. |
|
e |
Extended: |
Surface color extended to the very end of the hair shaft. |
|
Other |
Different |
Genes affecting coat color that are not in the A-E series |
|
R (1-4) |
Rufus: |
Adds red coloration to tan/cream, up to 4 seperate alleles displaying an entirely additive effect (more genes=darker red). |
|
WM(or V) |
Vienna: |
Dominant white spotting gene with incomplete penetrance (WMWM or VV is a Blue Eyed White). |
The alleles present in each subset cannot change the alleles in other
subsets, but they can alter their appearance. Most of the coat color
alleles in rabbits undergo what is known as independent assortment,
meaning that when the rabbit reproduces, it has an equal chance of
passing along either of its two alleles in each subset to its
offspring. Only the B and C subsets are linked, but not so closely as to eliminate crossover events. "New" colors are almost always produced by recombining
genes already present, and very few new mutations are seen.
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The only things you will need to genotype your rabbits is a pencil, a
piece of paper, and, of course, the rabbits. Other helpful things to
have are the pedigrees of each animal (listing colors) and a record
of the color of the progeny of each animal, if any, and what color
the other parent was. I suggest you use a form listing all of the
animals involved in your breeding program. You can make this form
yourself, or print off the example. If you are making your own form,
make a column to list the number or name of each rabbit, one for the
visible color, and then five for the genotype, labeled A, B, C, D,
and E as in the sample. You can also include any other information
you desire, but avoid making the form too complex. It is best to
leave extra space above or below each entry in case you make a
mistake. Make as many of these sheets as you need to accommodate the
number of rabbits you intend to genotype. To make your work easier,
list rabbits of the same color together on the sheet and group the
bucks and does separately so you can more easily find a possible or
past mate. The most important thing is to write in pencil unless you
are positive of an animal's genotype.
To begin genotyping, you must be systematic. The whole process can become confusing if not approached properly. Look at the effects of each allele separately, because each one can affect the appearance of the others. If in doubt about a specific allele, leave blank spaces for any alleles which you do not know for certain.
This is the best and most direct way to gain information on
the genotype. Begin by examining each animal on your list in a well
lit area.
1. If the animal is an albino, a Ruby Eyed White, record cc in column
C. This is all of the information you will be able to obtain just by
looking at this animal. If the only color on the animal is confined
to the nose, ears, feet and tail and it has pink eyes, it is a
pointed white, so record ch in column C.
2. If the animal is not REW, you will be able to get more information
on the genotype.
A. Agouti: Examine the animal's hair shaft by blowing into the coat.
Also, examine the animal's belly, inside of ears and underside of its
tail. If any of these regions appear white or cream, or the hair
shaft is composed of two or more different colored regions, this in
an agouti animal so enter A in column A. If the belly is the same
color as the back and the hair is one color, the animal is a self, so
enter aa in column A.
B. Black/Brown: Now examine the animal's body fur and tips of the
ears. If you see any black or bright blue on any hair, enter B in the
second column. If there is no black or blue on the animal, but it
does have a pure chocolate brown or light pinkish dove gray, enter bb
in column B. If it has a sepia brown or smokey color in these
regions, it is being affected by the C group, and although these
genotypes do affect the appearance of surface shading, it is better
to wait with the B series entry until more information is
available.
C. Color Expression: This allele is more complex and has several
possibilities. If the animal is an agouti or tan, it can be
determined visualy. If there is any red or tan brown on the animal,
record C in column C. If there is no tan brown, but instead a bright
silver or white, and the surface color appears black, blue,
chocolate, or lilac record cw. If the animal is a self, one solid
color with no shading, it can not be determined if it is C or cw. If
there is no tan brown and the surface color appears shaded record cs.
If the animal was a pointed white or REW, this would have been
recorded earlier.
D. Density of Surface Color: If the animal displays dark (black,
chocolate, or sable) coloration, record D in column D. If there are
no dark colors on the animal but instead blue or dove or smokey gray,
record dd.
E. Extension of Surface Color: If the color over the animal's hair
shaft is dark with only a light band near the tip and the inside of
ears and belly are dark record Es in column five. If the dark and
light colors are distributed from the base to the tip of the hair
shaft and the inside of ears, nostils, and belly are lighter record
E. If the shaft is mostly light tan or silver with only a tipping of
dark at the very end, and this ticking being more prominent near the
head and rump of the animal, record ee in the fifth column.
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Examine the genotype that you have written out for the parents of
each animal in question. If a parent of an animal has two recessive
alleles in any one blank, you will know that it passed these on and
thus the offspring must have at least one copy of these recessive
genes. This process will help you fill in many blank spaces on your
form.
If the genotype of one or both parents is known, you will have some
idea of what the offspring might carry. Thus, the genotype of the
offspring may be one of two or three possibilities. If these
possibilities are written on the list in x or y format, future
breedings of that animal may be planned to determine the
genotype.
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Examining the offspring of an animal can also reveal much
information about the parent. Any young animal receiving two
recessive copies of a gene must have received one from each parent,
thus both parents carry at least one copy of the recessive.
If the phenotype of offspring is used for genotyping parents,
however, be careful not to be too hasty in assigning a genotype if
the other parent in question might have been the actual contributor.
This is not a problem with the A, B, or D alleles since there is only
one recessive possibility, but when dealing with E, and C especially,
there can be problems in determining which parent contributed
what.
Examination of the litter mattes and distant relatives can sometimes
help, but is usually not a reliable indicator of the genotypes of the
rabbit in question. Remember that there is nothing wrong with leaving
a few blanks, and usually the true genotype will be eventually
revealed. Examining the pedigree might also help in determining
possible genotyping, but remember that a pedigree is only as good as
the writer. It is also a good idea to examine the pedigrees of
animals you own or intend to purchase to be sure a mistake was not
made in the past. Don't purchase rabbits with obviously
fraudulent pedigrees, as this type of pedigree is worthless.
This article to complicated? Want to skip the hassle? Click here to skip to the direct DNA tests, now available for Rabbits!!!!!!