Friday, July 22, 2016

New Zealand Rabbit Genetics: Putting It All Together



So how did I get started down this road to try and decipher the genetic makeup of the New Zealand (NZ) rabbit? The answer is pretty simple really. Like many people new to breeding rabbits, I thought that If I bred a New Zealand Red (NZR) with a New Zealand White (NZW) then surely I should see some red, white, and possibly some red and white (broken or charlie) offspring (kits) in my litters. What I found out was that always got chestnuts, and or dark colored steel tipped kits from these pairings with no whites, reds, or patterned (broken or charlie) offspring. My NZR to NZR pairings always resulted in beautiful red offspring with no variations in color or color patterns. While my NZW to NZW pairings almost always produce white kits, I had one female who continued to occasionally produce a black litter when she was bred with a white male from another breeder friend of mine which kind of baffled me. So I decided that after three years of raising and breeding rabbits it was time to dive into the subject of genetics and the NZ rabbit genome.

In the second article of this series 'Coat Color: It's In The Genes' we examined the entire NZ rabbit genome or genotype and at the end of the article I listed the basic genotype of each of the NZ rabbit color combinations. Just for convenience I am going to re-list those color gene sequences below for your reference.

Agouti (Chestnut): A_, B_, C_, D_, E_, enen, DuDu, SiSi, VV, W_
Black: aa, B_, C_, D_, E_, enen, DuDu, SiSi, VV, W_
Blue: aa, B_, C_, dd, E_, enen, DuDu, SiSi, VV, W_
Red: A_, B_, C_, D_, ee, enen, DuDu, SiSi, VV, ww +++
White: A_, B_, cc, D_, E_, enen, DuDu, SiSi, VV, W_

The Brokens:

Black: aa, B_, C_, D_, E_, Enen, DuDu, SiSi, VV, W_
Blue: aa, B_, C_, dd, E_, Enen, DuDu, SiSi, VV, W_
Red: A_, B_, C_, D_, ee, Enen, DuDu, SiSi, VV, ww +++

The Charlies:

Black: aa, B_, C_, D_, E_, EnEn, DuDu, SiSi, VV, W_
Blue: aa, B_, C_, dd, E_, EnEn, DuDu, SiSi, VV, W_
Red: A_, B_, C_, D_, ee, EnEn, DuDu, SiSi, VV, ww +++

As I mentioned in 'Coat Color: It's In The Genes' all NZR's share the (DuDu), (SiSi), and (VV) allele pairings so many breeders simply drop these when denoting the NZR genotype. For the rest of this article I will be doing the same, just know that if you want a complete 10 color genome listing add the proper allele pairings to the genome. So The basic genome of the breed would look as follows when abbreviated. NZ rabbit basic color genome: A_, B_, C_, D_, E_, en_, W_.


Putting It All Together

Without DNA testing, there is only one way you can try and fill in the blank spaces in your rabbit's genome. It's the method that breeders of livestock have used for thousands of years and that is simply breeding your rabbits and writing down your individual results. If you keep through consistent records you will eventually be able to fill in most of the blanks on your rabbits color genome based on your own out comes. The key here is consistency and good record keeping. If you are raising meat rabbits for just meat then you probably do not care what the rabbit's coat color looks like as all the meat tastes the same regardless of coat color. However, if you want to breed for a specific color or color pattern in order to increase not only your breeding stock, but potential sales of breeding stock, then it is good to have an idea of the genetic makeup of your rabbits. Eventually most breeders not only want to supply their family with meat to eat, but rabbit sales to supplement their income or at least pay their feed bills.


The New Zealand Agouti “Chestnut”
Basic Genome: A_, B_, C_, D_, E_, enen, W_

The New Zealand Agouti (NZR) is the original color of the breed. The upper coat is a reddish sorrel color, with the pigment running the length of the hair shaft. The coat on the belly color tends to be the same color with a slight lightening or cream color in the middle of the abdomen, the underside of the tail, the front or rear food pads and around the eyes. Their eyes are brown in color. The NZR carries the agouti (A_) gene and when breed with self (aa) colored NZ rabbits will possibly produce steel-tipped kits as well as a variety of different shades depending on other genetic modifiers.


The New Zealand Black
Basic Genome: aa, B_, C_, D_, E_, enen, W_
Broken Black Basic Genome: aa, B_, C_, D_, E_, Enen, W_

The New Zealand Black (NZB) has an upper coat with a uniform dark black throughout. The undercoat may be a uniform, black color or it may be a dark slate blue color with dark brown eyes. The NZB is a self (aa) colored rabbit and when bred with another with self (aa) colored NZ rabbit will possibly produce steel-tipped kits as well as a variety of different shades depending on other genetic modifiers.


The New Zealand Blue
Basic Genome: aa, B_, C_, dd, E_, enen, W_
Broken Blue Basic Genome: aa, B_, C_, dd, E_, Enen, W_

The New Zealand Black (NZBL) has an upper coat with a uniform dark black throughout. It is the dilute (dd) allele pairing that causes the black (B_) allele to become diluted from a black to blue coat. The undercoat may be a uniform, blue color or it may be a dark slate blue color with dark brown eyes. The NZBL is a self (aa) colored rabbit and when bred with another with self (aa) colored NZ rabbit will possibly produce steel-tipped kits as well as a variety of different shades depending on other genetic modifiers.




The New Zealand Red
Basic Genome: A_, B_, C_, D_, ee, enen, ww, rufus-modifier
Broken Red Basic Genome: A_, B_, C_, D_, ee, Enen, ww, rufus-modifier

The New Zealand Red (NZR) is the original color of the breed. The upper coat is a reddish sorrel color, with the pigment running the length of the hair shaft. The coat on the belly color tends to be the same color with a slight lightening or cream color in the middle of the abdomen, the underside of the tail, the front or rear food pads and a around the eyes. Their eyes are brown in color. The NZR carries the agouti (A_) gene and when breed with self (aa) colored NZ rabbits will possibly produce steel-tipped kits as well as a variety of different shades depending on other genetic modifiers.


The New Zealand White or 'Ruby Eyed White' (REW)
Basic Genome: A_, B_, cc, D_, E_, enen, W_

The New Zealand White (NZW) is probably the rabbit that most people think of when you mention the words “New Zealand Rabbit”. It is the most commercially produced as well as breed for show variety of the NZ rabbits. In fact, it is the gold standard for commercial rabbit meat production and laboratory testing as well as a great rabbit to breed at home for meat production. The NZW is technically and albino (lack of melanin), because the NZW is an albino, the other genes colors that would normally make up it's genetic code are suppressed. That does not mean that the other color gene's are not there, rather the albino gene (cc) blocks the color of all the pigments along the hair shaft and eyes, producing a white rabbit with pink/red eyes known as a 'ruby-eyed white (REW)'. It can still be a carrier for all the other genes, it is just that you may not see their expression until you breed a white rabbit with a rabbit of another color.




The Breeding Trials

So let's look at how you can begin to fill in some of the blank spaces on you NZ rabbits genome. I have listed the basic color genome for our NZR buck 'Long Eared Red' (LER) and the our NZW doe Luna which we have breed to several times. For whatever reason she is most responsive to this buck so I almost always breed her to him. LER's red coloring is right in the middle of the red color range so my best guess is that he has three rufus-modifiers denoted as (+++) at the end of his genome, the words 'rufus-modifier' have been replaced by this notation. As I mentioned earlier their pairings always produce either agouti's and or steel tipped kits. Looking at the various litters that these two rabbits have produced, I can now begin to apply some of my knowledge to start and flesh out their color genome's.

Our NZR buck 'LER's' Basic Genome: A_, B_, C_, D_, ee, enen, ww, +++
Our NZW doe “Luna's' Basic Genome: A _, B_, cc, D_, E_, enen,W_,

I have bred these two rabbits multiple times and I always get a combination of chestnut agouti's and black cinnamon tipped steel kits, the majority of them being steel tipped. So let's see if we can flesh out the color genome of these two rabbits gene by gene. It is important to remember that each parent gives one allele to it's offspring to complete the pair. Knowing this, we can look at their offspring to help us to fill in the blanks in their genetic color code.

Their last litter basic genome:

2 - Chestnut Agouti's Aa, B_, C_, D_, Ee, enen, Ww
5 – Black Cinnamon Tipped Steels aa, B_, C_, D_, Ese, enen, Ww




A-Series Genes: Agouti (A_) allele, and Self (a_) allele
Possible Allele Pairings: Agouti Rabbits (AA, Aa), Self Colored Rabbits (aa)

The A-Series of genes has only two possible possibilities in NZ rabbits, agouti or self. If one dominant agouti (A_) allele is present you get a rabbit with agouti characteristics, if two recessive agouti (a_) alleles are present you get a self colored rabbit. Because the breeding of LER and Luna continue to produce some self colored (black) rabbits with steel tips then the both must carry the (Aa) pairing. So our first gene for these two rabbits is complete.

Our NZR buck 'LER's' Basic Genome: Aa, B_, C_, D_, ee, enen, ww, +++
Our NZW doe 'Luna's' Basic Genome: Aa, B_, cc, D_, E_, enen, W_,


B-Series Of Genes: Black (B_) allele or Brown (b_) allele
Possible Allele Pairings: Black Colored Rabbits (BB, Bb), Brown Colored Rabbits (bb)

This gene then determines whether the rabbits base coat color is black or brown. Because the black (B_) allele is dominant over the brown (b_) allele, black is the most common color. The allele pairings (BB) or (Bb) will always produce a black, while the recessive (bb) allele pairing will always produce a brown rabbit. Because there are no brown colored NZ rabbits, I will go out on a limb here and say that both LER and Luna carry the (BB) allele pairing. It is possible that one of rabbits carries the (Bb) allele pairing, but one of them is a (BB) for sure, I just do not know which one at this time.

Our NZR buck 'LER's' Basic Genome: Aa, BB, C_, D_, ee, enen, ww, +++
Our NZW doe 'Luna's' Basic Genome: Aa, BB, cc, D_, E_, enen, W_,


C-Series Of Genes: Complete (C_) allele, Incomplete (c_) allele
Possible Allele Pairings: Complete Colored Rabbits (CC, Cc), Albino Rabbits (cc)

The C-series of genes determines whether a rabbits coat has complete color or no color. The dominant (C_) allele allows all four of the dark and all three of the yellow pigments to be present in the hair shaft. This allows for full color development of the rabbits coat and works with the E-series of genes and their alleles to produce ticking or steel tipped colors in rabbits that carry the agouti (A_) allele. A NZ rabbit with two recessive (c_) allele's is classified as an albino (white rabbit with red eyes). Because multiple pairings of LER and Luna have never produced any white kits, and you have to have a (cc) allele pairing to produce white kits, we know that LER carries a (CC) allele pairing. If he carried the (Cc) allele pairing, eventually they would produce a white kit (cc), but this has never happened.

Our NZR buck 'LER's' Basic Genome: Aa, BB, CC, D_, ee, enen, ww, +++
Our NZW doe 'Luna's' Basic Genome: Aa, BB, cc, D_, E_, enen, W_,


D-Series Of Genes: Dense (D_) allele or Dilute (d_) allele
Possible Allele Pairings: Dense Coat (DD, Dd), Dilute Coat (dd)

The D-series of genes determines the depth of color of the coat of the rabbit. Rabbits with at least one dense (D_) allele have full color shades that are are darker (black or chestnut), and generally have brown eyes. Rabbits with a dilute (d_) allele have a lighter more sedated or dilute colored pigment in the hair shaft causing the coat to be lighter in color. Unfortunately I have no definitive way to determine the 'D' allele pairings of these two rabbits. All of their kits appear to have a nice dark definitive coats, so I am leaning towards (DD) for both, but because I confirm that I will leave them as undetermined (D_).

Our NZR buck 'LER's' Basic Genome: Aa, BB, CC, D_, ee, enen, ww, +++
Our NZW doe 'Luna's' Basic Genome: Aa, BB, cc, D_, E_, enen, W_,


E-Series Of Genes: Steel Extension (Es_) allele, Normal Extension (E_) allele,
Non-extension (e_) allele
Possible Allele Pairings: Steel Tipped Rabbits (EsEs, EsE, Ese), Black Rabbits (EE, Ee), Red Rabbits (ee)

The (Es_) allele works in combination with the agouti (A_) allele and is responsible for producing the ticking or steel patterns (Gold or Cinnamon tipped). So in order for a NZ doe to produce kits with steel characteristics (tipped hair coloring) either the buck, doe, or both must carry an agouti (A_) allele. If both rabbits in the breeding pair carry the self colored (aa) allele pair, they cannot produce kits with steel tipped fur. Because our NZR buck 'LER' carries a non-extension (ee) gene, and NZR's also carry the dominant agouti (A_) allele, and we get some steel tipped kits, then we know our NZW doe Luna must carry the steel extension (Es) in her basic genome. In addition, because all NZR rabbits are (ee), and this pairing never produces any litters with red rabbits then her 'E' gene pairing must be (EsE).

Our NZR buck 'LER's' Basic Genome: Aa, BB, CC, D_, ee, enen, ww, +++
Our NZW doe 'Luna's' Basic Genome: Aa, BB, cc, D_, EsE, enen, W_,


W-Series Of Genes: Normal Width (W_) allele, Double Width (ww) allele
Possible allele Pairings: (WW), (Ww), and (ww)

The dominant normal width (W_) gene produces a yellow or white agouti color band in the hair shaft producing a normal coloring. The recessive double width (ww) gene doubles the width of the yellow or white agouti band in the hair shaft causing the rabbit to have the characteristic agouti patterns typical of the new Zealand Red. Because of NZR buck LER carries the double width (ww) agouti gene which produces the standard agouti patterns around the eyes, triangle at the nape of the neck, feet, legs, ear, and inside of the belly. However, none of the the steel tipped kits exhibit these patterns, and this pairing has never produced any litters with red rabbits Therefore Luna must carry a (WW) allele pairing.

Our NZR buck 'LER's' Basic Genome: Aa, BB, CC, D_, ee, enen, ww, +++
Our NZW doe 'Luna's' Basic Genome: Aa, BB, cc, D_, EsE, enen, WW,

For this particular pairing of rabbits, fleshing out their genome was pretty straightforward. The whole process is simply a matter of looking at the types of offspring that this breeding produces. If Luna was bred to a white buck, then I would have been unable to unravel both her or LER's color genome as all the pigments in their offspring would be suppressed by the (cc) allele which produces albinos, aka. Ruby-eyed Whites (REW). Once we know the genome of the parents, we can then produce an accurate genome of their offspring.




Their last litter complete genome (almost):

2 - Chestnut Agouti's: Aa, BB, Cc, D_, Ee, enen, Ww
5 – Black Cinnamon Tipped Steels: aa, BB, Cc, D_, Ese, enen, Ww


Conclusion

I know this may seem like a lengthy process, but it is fairly easy, and once you have done it a few times it goes really fast. You just have to understand that determining the color genome of some rabbits is easier than others, and you need to look at more than one litter to be able to accurately determine the genetic color makeup of the rabbits in your herd. If you have read all three of the articles in this series you may think to yourself, I am just not interested in knowing this. That's fine, but remember if you what to be able to produce consistent litters of specific colors to sell as breeding stock, knowing the genetic color makeup of your herd will help you to become more successful.

The more genetic variables you have in your herd, the harder it is to consistently reproduce the desired characteristics in your herd's offspring whether it be size, shape, and or color. When adding new livestock to your herd, a pedigree helps because it usually contains the basic weight and color characteristics of the rabbits ancestors. Just remember however that a pedigree does not always guarantee you quality, that final determination must be made by you when you examine the rabbit prior to purchase. As always, if you have found this article interesting or informational please share it with your friends. Don't forget to follow us on Facebook or on Google+ for the latest articles on our blog related to raising your own meat rabbits.





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