Plain English explanation for Dun

[Donlin Stud]

Hi everyone

The below is my version of explaining in plain English how Dun occurs.

Can you have a looksee and let me know if it can be more plain so I can confidently share with new to the breed owners?
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The Dexter Genetic Colours

Q: So why is it referred to as Dexter dun?

A: The dun appearance in the Dexter breed is unique because of the way it is created.

Rules:

• Genes only ever come in pairs – one from each parent.
• There is only black or red genes for colour in the Dexter breed.
• The black gene is dominant over the red gene

So a Dexter can have either:

- two black genes or
- one black and one red gene, or
- two red genes.

To confuse you just a little:

Dexters have two different types of red genes: True red and Wild red – but these are explained lower down

So how are there Dun coloured Dexters then?

• In the Dexter, each coloured gene has an allele friend called MC1R
• MC1R gives instructions to the coloured gene it is attached too telling it how to distribute / spread the colour pigment.

In the Dexter, the saying two is company and three is a crowd applies because sometimes, there is a hitchhiker called TYPR1 that will hitch a ride with MC1R.

• TYPR1 causes MC1R to become confused when it is giving instructions to the coloured gene.
• When MC1R is confused when instructing a black gene – the pigment is spread very thinly (diluted) causing the appearance of dun instead of black.
For some unknown reason, TYPR1 cannot cause MC1R to become confused when instructing a red gene and TYPR1 cannot confuse two MC1Rs at the same time. It can only confuse the MC1R it is attached too.

Remember I said that:

1. Black is the dominant colour?

2. A parent gives one coloured gene with MC1R to its offspring with the other parent giving its own coloured gene with MC1R?

3. And there must be two of every gene?


Well if a Dexter has one black gene with MC1R and a hitchhiker TYPR1, and the other parent gives the offspring a black gene with MC1R but no hitchhiking TYPR1, then the offspring will be black in colour.
Why?

Because only the MC1R that the TYPR1 hitchhiked with can become confused by it.
The other MC1R from the other parent won’t listen, and because black is the dominant colour – the resulting offspring will be black in colour, not dun.

So to have a dun Dexter: there must be one black gene with MC1R and a hitchhiker TYPR1, and the other parent must also send TYPR1 with its coloured gene (which can be red or black) with MC1R . When this happens, the offspring will be dun.

Here is the explanation in a table format:

ED = Black
b = Dun (TYPR1)
E+ = Wild red
e = True red

Dexters will be black in colour when:

ED/ED = black in colour only
ED/ED+ &b = black in colour but dun carrier
ED/E+ &b = Black in colour but dun AND red carrier
ED/e &b = black in colour but dun AND red carrier

Dexters will be red in colour when:

E+/E+ = red in colour
E+/e = red in colour
e/e = red in colour

These Dexters while red in colour can also carry dun - see next:

E+ &b/E+ = red in colour but capable of producing dun if mate has black gene + b given to progeny
E+ &b/E+ &b = red in colour but capable of producing dun if mate has black gene + b given to progeny
E+ &b/e = red in colour but capable of producing dun if mate has black gene + b given to progeny
e &b/e = red in colour but capable of producing dun if mate has black gene + b given to progeny
e &b/e &b = red in colour but capable of producing dun if mate has black gene + TYPR1 (b) given to progeny

Dexters will be dun in colour when:

ED &b/ED &b = dun in colour – but because there is also at least one copy of the black, duns are always black carriers
ED &b/E+ &b = dun in colour but red AND black carrier
ED &b/e &b = dun in colour but red AND black carrier

There are many reports of a dun coloured Dexter suddenly appearing after many generations of only black coloured Dexters on both side of the family.

.......................................................

Colour testing of parents is the only way you can estimate what colour the calves may be.


The two types of Red Explained

Dexters have two types of red coloured genes:

E+ known as Wild Red and ‘e’ which is known as True red.

Either type of red gene, or combination of still only produces a red coloured Dexter.
The saying only reds breed true is because red is recessive so when both parents are coloured red, they can only have red coloured offspring. (Even if they both parents both carry two copies of TYPR1 - they will still only produce red coloured offspring)

The red gene referred to as Wild red (E+) is called this because it is made up of both red and black pigment.
True red (e) is called true because it is only made up of red pigment.

Some say that Dexters with one or two copies of E+ have a deeper, richer red coloured coat.

The E+ can also be responsible for dark to near black patches on a Dexter's red coloured coat.

[karenp]

A couple of questions to clarify, the double + signs are confusing to me. Should I be reading "E++b/E+ = red in colour but capable of producing dun if mate has black gene + b given to progeny" as E+&b/E+...or does it mean something else?

Is the E+ the red with a black nose and e the more beige?

[Donlin Stud]

Jun 21, 2016 12:28:13 GMT karenp said:

A couple of questions to clarify, the double + signs are confusing to me. Should I be reading "E++b/E+ = red in colour but capable of producing dun if mate has black gene + b given to progeny" as E+&b/E+...or does it mean something else?

Is the E+ the red with a black nose and e the more beige?

Hello

Yes I grapple with the double ++'s. I love the way you have come up with the &. I just didn't think of that. - Thank you

[Tell me if I don't answer your question ]

E+  +b / E+ is a Dexter Wild red in colour that carries a single copy of dun

So yes, this Dexter could produce a dun coloured calf _IF_ it passes the single copy of dun to its offspring _and_other parent gives a black gene also with dun (b) to the offspring.

By default, the calf if dun in colour would be a wild red carrier [and also a black carrier but this term is rarely if ever used)

If calf is red in colour, testing would be required to see if either or both [or none] of the dun was passed to the offspring.

Yes, that is the generalisation that Wild red produces the black nose and the True red usually the beige nose.

But not always: our girl Bindi tested as E+&b/E+&b, and her nose is a darkish beige but I wouldn't say its black or greyish or such. 
Our Hank tested E+/E+ and his nose is also not black but darker than the girl above.

Just trying to think if we have a e/e in the herd - will check my test results. We do have True red but its in our red carriers who are either black or dun in colour.

Going to change the above to show E=&b/ etc.........

[karenp]

Do you find that the "carries red" effects the shade of dun? There seems to be a wide range.

[Donlin Stud]

I tried to work that out ages ago but we cant see it.
We have 11 duns now and every single one of them is a different shade to the others.

Some carry e; some carry E+ and others are just black carriers (so to speak

Do you remember this post from way back Click on the date and time links NOT my username link and it will take you to the post of the time with pics.

Mar 12, 2015 2:32:31 GMT Donlin Stud said:

This is one of our 2014 dun babies at the age of 3-4 days.

This young boy has since been tested and he does NOT carry red.

He is nearing 21 months of age and he is still a very dark dun, that is darkening as winter takes hold.
The complete opposite to out other duns who lighten as the weather chills.

On Judy's recommendation we sent pics, hair etc of him to UCD.

UCD explained that because TYPR1 'dilutes' it would be very difficult to expect the dilution to occur at the same level every time.

There is still so much to learn about the dun colouring in Dexters. The identification and the role of TYPR1 is only the tip of the iceberg.
So is assessing the difference between calf coat colours and adult coats.

My daughter was absolutely horrified that we decided to rehome his sire: she loves the colour of Bear's eyes.

So different from the other duns' eye colour shades against coat colours.

Not sure if this pic gives it any justice at all but I do have to agree with her - he does have exceptional colouring of the eyes.

Bear was meant to be in his new home already but we have had several significant rain events either flooding us in or the new owners i.

Fingers are crossed for this weekend

[Deleted]

I have no red in my herd so cant speak to that. What I do see is that black calves that carry dun do tend to be lighter until their second coat comes in. this does not happen in every case but often enough I think there is something to it. I have yet to have a black calf that did not carry dun that was any shade other than black at birth.

[teatpuller11]

Donlin, good on yer for taking this on. (That about the extent of my Aussie talk.)

Would it help you if you went back to the source to check out your work?  I think it was someone in the ADCA who did the dna work, and there used to be an explanation on their website.  I'd think he'd be the one to ask.  My opinion is just an amateur's understanding.  I'd think it best to make sure the explanation is right before worrying about it being understood by people like me.

[Donlin Stud]

Jun 22, 2016 15:49:56 GMT teatpuller11 said:

Donlin, good on yer for taking this on. (That about the extent of my Aussie talk.)

Would it help you if you went back to the source to check out your work?  I think it was someone in the ADCA who did the dna work, and there used to be an explanation on their website.  I'd think he'd be the one to ask.  My opinion is just an amateur's understanding.  I'd think it best to make sure the explanation is right before worrying about it being understood by people like me.

Not quite there teatpuller - its Good on ya !
We don't elongate but cut off abruptly.

I wasnt seeking a confirmation of the accuracy as I know it to be correct.

While scientists like to see every description of genetic testing in scientific terminology - the average person just wants a simple explanation, that is easily understood without running for a dictionary or such to digest and then put into practice.

So was seeking feedback if this explanation was in plain English version using every day words that wouldn't be confusing or still required a lot of brain power to work through.

Increasing the chance of producing dun coloured calves in one's herd is not complicated thanks to DNA testing and a general understanding of the genes.

But thank you for the info.

[Donlin Stud]

Jun 22, 2016 14:20:47 GMT @dexterfarm said:

What I do see is that black calves that carry dun do tend to be lighter until their second coat comes in. this does not happen in every case but often enough I think there is something to it. I have yet to have a black calf that did not carry dun that was any shade other than black at birth.

Check out this little man not yet 6 month old in photo below. That's mum with him and the black butt in background is dad

Today at just over 3 years of age he is as black and sleek as can be.
He is a bit of a worry in winter as his coat is more sleek, not thickening as much as most.

We have had  a couple of calves that were jet black, and remained so (maybe lightening a fraction on ear tops and end of coat hairs in summer) that are dun carriers, and both do not carry red.

Looking for their photos in my Dexter Album.............stay tuned.

[Deleted]

I think you may loose a lot of people when you start talking abbreviations and locations. Start off with a simple explanation and then you can go into more detail.

Black is dominate over red. In order for a calf to be red it must inherit red from both parents.

Dun is a separate gene that affects the black colored animals to give the various shades of dun we see. Dun will only affect the black color if it was inherited from both parents. Dun has no effect on a red colored calf.


Something like this should explain it for most everyone and for most people that may be all they want to know. Then you could go into your more detailed information. 

[karenp]

Jun 23, 2016 14:40:07 GMT @dexterfarm said:

I think you may loose a lot of people when you start talking abbreviations and locations. Start off with a simple explanation and then you can go into more detail.

Black is dominate over red. In order for a calf to be red it must inherit red from both parents.

Dun is a separate gene that affects the black colored animals to give the various shades of dun we see. Dun will only affect the black color if it was inherited from both parents. Dun has no effect on a red colored calf.


Something like this should explain it for most everyone and for most people that may be all they want to know. Then you could go into your more detailed information. 

"Dexters will be dun in colour when:



ED &b/ED &b = dun in colour – but because there is also at least one copy of the black, duns are always black carriers

ED &b/E+ &b = dun in colour but red AND black carrier

ED &b/e &b = dun in colour but red AND black carrier"

Am I misunderstanding? These two statements seem to contradict. When you say the "Dun will only affect the black color if it was inherited from both parents" are you saying the dun must be inherited from both parents (which I understand) or the black must also be inherited from both parents making the calf homozygous for black and unable to carry red? 

[Deleted]

Dun will only affect the black color if dun was inherited from both parents.

does it read better like that?

[karenp]

yes

[wvdexters]

It is good you all are doing this. I think color and understanding how it works in Dexters is the most difficult thing for new comers to really get. It sure was for me, and even now sometimes I have to stop and think.

We have straight black (no color) to all color (red/dun)in our little herd. Plus both e and E+. Keeps things interesting

[karenp]

So to expand this a little, what about e/E+, is one dominate? Do they somehow combine and create a different version of red?

[teatpuller11]

From what I've red, the color experts say both can be any tone, but black shadings are found with wild red? Color can be really interesting. Wonder when they'll find the location of the brindle gene?

[Donlin Stud]

This is wonderful everyone.

I will have another go at the explanation as suggested Dexterfarm and see if we together cant make this info as plain as we can

wvdexters yes, colour is always near the first question we wanted answers for and our new moo owners are the same

[wvdexters]

Karen, With our reds here. Judith (E+/e, B/b) is the same shade as her sire Macklynn (e/e, b/b). No dark shadings.