Dexter Cattle For Sale Discussion Board

Posted: **Sun May 13, 2007 10:40 pm**

how do we get the dun colour
simple question
but not so simple answer i think

Posted: **Sun May 13, 2007 11:16 pm**

A quick answer from me, probably will be followed by more accurate stuff from the serious geneticists.
The Dun colour seen in Dexters is controlled by a recessive gene which dilutes the colour black, and is different from the dun seen in galloways, simmentals etc. It seems to be exculsive to Dexters, and probably most closely associated with ones with Woodmagic breeding.
Being a recessive gene it requires one to be inherited from each parent before the colour shows itself, so if we assume that b is a black gene, red is r, d is dun. Each animal will be either bb rr or rb, and may or may not have one or two dun genes. So possiblities are

bb will be black, carries no red or dun
bbd will be black, carries dun
bbdd will be dun
br will be black carries red
brd will be black carries red and dun
brdd will be dun, carries red
rrd will be red, carries dun
rrdd will be red, carries two dun genes so may give a dun if mated to a dun or black carrying dun.

As you may see, there are loads of possibilities if you work out all the possible matings and outcomes.

I may not have al this exactly right, anyone is welcome to correct me. I have in the past tried to map out all possible matings and their possible outcomes, but it need a very large sheet of paper.

Duncan, (trying to keep it simple as usual because that is the way I think myself.)

Posted: **Mon May 14, 2007 12:46 am**

Here's the genetics science (simplified, I hope):

The primary gene locus for color in Dexters is the extension locus, or E locus. Extension stands for the "extension" of the two pigments (red and black) across the body of the animal. Locus just means the place where the genes for that particular function reside.

There are three choices (alleles) at the E locus:

D = Dominant Black
+ = Wild type Red (Red with some black pigment mixed in)
e = recessive true red (Red with no black pigment mixed in)

You can notate genes by listing the letter for the locus (E = Extension locus), followed by the allele (D, +, or e in this case)

The possible gene pair combinations at the E locus are:

ED/ED = Black (homozygous)
ED/E+ = Black but carries wild-type red
ED/Ee = Black but carries recessive true red

E+/E+ = Wild-Type Red (homozygous)
E+/Ee = Wild-Type Red but carries true red

Ee/Ee = True Red

Another gene locus is the Brown Locus or B locus. This occurs in many animals including cattle, dogs, sheep, goats, and others. The B locus helps the black pigment (provided by the E locus) complete its production. If the production of black pigment is successfully completed, you get the color black. If the last step in black pigment production is omitted, then the black pigment remains incomplete and looks brown (called dun, in Dexters). So a dun Dexter is really just an incomplete black Dexter.

The gene choices (alleles) at the B locus are:

B = Dominant Neutral - Provides for the completion of black
b = recessive brown - interferes with the completion of black

The possible gene pair combinations at the B locus are:

BB/BB = Neutral (Don't interfere with black, so no dun)
BB/Bb = Neutral but carries a recessive dun gene
bb/bb = dun (but only if the E locus calls for black)

Now remember, that to be dun, a Dexter must have one of the E locus combinations for black (at least one ED), then has to have bb/bb at the B locus to interfere with black, which makes dun. You can have a red with bb/bb at the B locus, but there is little or no black pigment to turn brown, so you won't be able to tell if a red Dexter is homozygous (has two genes) for dun by just looking.

Did I lose anyone? or better yet, did anyone make it this far without nodding off?

Kirk
www.cascademeadowsfarm.com

Posted: **Mon May 14, 2007 4:02 am**

Kirk, can you offer any clear advice on the black skinned red Dexter? I have broached this subject before, just generally, but to no avail.
We have Dexters in four colours. Black, dun, red with pink skin, and a much deeper darker red with black skin. The red with black skin has two pink skinned red parents, but the sire of the dam is red with black skin. Is this the normal expression of the wild gene in Dexters, or does it usually have pink skin?
Is the black skinned red an original Dexter colour, or is it indicative of introgression? When I first started asking this question, peolpe cringed, fearing lawsuits possibly.
Then came Carol Davidson's paper on colour, in which she states that she hoped there was not going to be the same discrimination against the wild red as there had been against the dun. I assumed that the wild gene must have been the answer to the black skinned red. Is that so?
Nowhere, in any of the articles on the red gene, does it mention skin colour of reds. Can you help, please?
Margaret.

Posted: **Mon May 14, 2007 6:34 am**

wagra dexters wrote:Kirk, can you offer any clear advice on the black skinned red Dexter? I have broached this subject before, just generally, but to no avail.
We have Dexters in four colours. Black, dun, red with pink skin, and a much deeper darker red with black skin. The red with black skin has two pink skinned red parents, but the sire of the dam is red with black skin. Is this the normal expression of the wild gene in Dexters, or does it usually have pink skin?
Is the black skinned red an original Dexter colour, or is it indicative of introgression? When I first started asking this question, peolpe cringed, fearing lawsuits possibly.
Then came Carol Davidson's paper on colour, in which she states that she hoped there was not going to be the same discrimination against the wild red as there had been against the dun. I assumed that the wild gene must have been the answer to the black skinned red. Is that so?
Nowhere, in any of the articles on the red gene, does it mention skin colour of reds. Can you help, please?
Margaret.

Well, I just so happen to have a black skinned red story to tell you. We have been focusing on pink nosed true-red polled animals in our herd, although we a few blacks around for variety(and it makes it easier to do a head count). Our herdsire is homozygous polled and homozygous true red Ee/Ee. One of our best females is a black, carrying red, polled cow named Heather. She is heavily line bred to Saltaire Platinum and Cornahir Outlaw.

I've been praying for a red bull out of Heather as a possible new herd sire. Well, four days ago my prayers were answered, she had a wonderful little red polled (possibly homozygously polled) bull calf at 10:30pm. I checked on the little calf and then went to bed all excited that my ship had come in. Then before I went to sleep, I remembered that of all of our animals, I was pretty certain that heather might carry a wild-type red instead of true red based on her pedigree, and then I thought, oh no, I hope the calf doesn't have a black nose. The next morning I ran out and took a look, sure enough there was a dark nose (not as dark as some I've seen). Now I think the dark noses kind of make sense for sun protection, but I greatly prefer the pink noses since all of ours have pink noses. Now I finally got my red polled bull out of Heather and he has a dark nose - darn it!

Nice story (don't you think?) now here's my theory, but first some known facts:

1. Wild-type red is called wild-type because it was pretty much the only basic color of of the wild predecessors of today's domestic cattle. The genetic symbol for the wild type is "+" at the extension (E) locus, hence E+.

2. Wild-type red (E+) gives the animal the ability to produce both red and black pigments, while true reds (have only red pigment) and blacks have black pigment (maybe some red pigment too, but it is hidden by the black).

3. Both black (ED) and True Red (written Ee or just e) are simple mutations from E+. These mutations are usually selected against in nature and you usually don't see solid black or solid red wild animals (but sometimes you do in some species).

4. Because E+ gives the animal two pigments to work with, it allows other gene loci to work with the two pigments to create multi-toned patterns, rather than sold black or solid red.

5. Many/most wild animals are E+/E+ (Homozygous Wild Type) because it gives them the ability to make red, black, brown, and gray patterns that help them hide, attract mates, provide natural sunscreen, etc. For example, think of some of the color patterns found in wild squirrels, wolves, badgers, deer, elk, etc.. They are all mostly E+E+.

6. Several other gene loci are involved in controlling the various patterns but they require E+ at the E locus.

Well, now you read my story, and read the known facts, now here's my theory based on observation, research, and discussion with a genetics geek:

There is a separate gene locus that controls black skin vs. pink skin. This locus is not effective in true reds (Ee/Ee) because they have no ability to produce black pigment. It is also not effective in blacks, because they are already black skinned. Now I know my little black nosed red bull is E+/Ee (Heterozygous Wild type red/true red). I suspect that the black skin gene may be dominant (although I suppose it could be recessive). I also suspect that it might react more strongly with homozygous Wild-type red E+/E+ than heterozygous E+/Ee because the E+E+ seems to have more black pigment to work with. Other genes that work with E+ are the brindle pattern, Jersey pattern including a white ring around the nose (doesn't mean you've got a recent Jersey introgression), and others.

As far these genetics being "proof" of recent introgression, that always makes me laugh for two reasons:

1. ED (Black) and Ee (True Red) are simple one letter mutation mistakes in copying the E+ gene so they occur regularly in the origins of nearly every species and breed of animal. Only regular culling of these mutations reduces their frequencies in breeds that aren't supposed to be red (like black Angus).

2. Breeds are a fairly new concept invented in the last one or two hundred years. Before that, each locale just had their local animals that matched their local environments. These animals are sometimes called land races. That's why many of today's breeds of animals are named after places. Before effective fences, all animals of a region intermixed with each other. If a farmer brought in animals from some other locale, they were absorbed into the local "breed". You can guarantee that Dexters had a variety of influences in their early developmental days and many of those genes, especially recessives, still pop up. Those early influences and the subsequent selection to match the environment are what makes Dexters, Dexters - so yes, Dexters share many genes with Angus, Jerseys, and certainly most other breeds of British cattle (probably some other European breeds too). With the advent of modern travel and modern fences, people started keeping breeds from other places, hence the idea of "breeds" vs. "the local cows", was born.

Without introgression, there are enough diverse genes in Dexters that via radical selection and breeding over a period of 50 years you could probably create wildly different breeds including ill-tempered very large white cattle. This underscores the fact that simply breeding a purebred Dexter to another purebred Dexter, won't maintain Dexters. You've got to continuously select and cull to a breed standard. It also underscores the fact that a little introgression won't do much other than introduce some genes that are probably already within the breed somewhere and and could be culled out if they don't match the standard.

A long answer to a simple question -

Kirk

Posted: **Mon May 14, 2007 10:13 am**

Thank you so much for writing all of this out. Very useful information. I shall print it off before I forget!

Penny

Posted: **Mon May 14, 2007 2:59 pm**

Thank you, Kirk. Black skinned red females and steers are a superb colour. We castrated a young bull a few years ago, because we did not know if it met standards, and the dark head colour returned to red, so that is obviously a secondary male characteristic.
Ours are also Platinum via Salty & Finnigan, and Outlaw, but with Knotting through the Danish bull, Bogevangen Hector, on the dam line. They are being criss-crossed to Hedgehog to bring the height back down to where we want it. We are not chasing poll.
The late Morna Arkle, whom I am fortunate to have met and conversed with, on the Gold Coast at the last Congress, was previously quoted as having claimed seven shades of black. Perhaps the same claim can be made of red, and also dun.
Margaret.

Posted: **Mon May 14, 2007 3:48 pm**

Nicely put, Kirk. I always wondered about those dark-skinned reds. I have a real mix at the moment; red horned, red polled, black, dun. No black-skinned reds though. By the way, how do you go about printing off these replies?? :O

Posted: **Mon May 14, 2007 5:40 pm**

Turn printer on. Have a look at 'print preview' to see how it will look and if OK click 'print'.

Posted: **Tue May 15, 2007 10:36 am**

I had a black-skinned red heifer. If you go to Broomcroft Farm, then Dexters, you'll see her in the last two photos.

She turned black after a few months. I can't put the picture in this site because of the URL format restrictions. Click on images to enlarge.

Posted: **Tue May 15, 2007 11:12 am**

The difference being she has a black mum, but I wonder what Kirk will make of her. Was she really as bright a red as she appears in the photo?
We had a steer like her, from a black mum, but he continued to be bright red until he was sold at 9 months.
Did you get round to looking up her breeding? About 5 generations would be good, if you ever have the time.
Margaret.

Posted: **Tue May 15, 2007 1:26 pm**

We've had calves born red, that turn black within 6 months. But the nose was black at birth.

We've had other calves born brown, that go completely black as they get older.

Posted: **Tue May 15, 2007 7:32 pm**

Hi Margaret

I've posted pedigree for Broomcroft Emile, with photos of her, mom & dad to This Temporary Site.

Yes, she was very red, not ginger, and had a black nose from day one.

Posted: **Wed May 16, 2007 6:07 am**

Broomcroft wrote:I had a black-skinned red heifer. If you go to Broomcroft Farm, then Dexters, you'll see her in the last two photos.

She turned black after a few months. I can't put the picture in this site because of the URL format restrictions. Click on images (to enlarge.

Based on the photos and the information you've provided, I will guess the following:

Your mother black cow definitely is an ED/E+ (One black gene and carries one wild-type red gene) and probably carries one or two copies of the black skin gene. Your very fine red bull likely is an E+/Ee (One wild-type red gene and one true-red gene). It may also be possible that he is an Ee/Ee (homozygous true red). Has he or his parents had a DNA color test?

The calf is likely an E+/E+ homozygous wild-type red. The E+/E+ allows maximum mix of both black and red pigments allowing other control loci to work with the pigments. The calf also has at least one copy of the black skin gene at the locus that controls that. There are likely some other color control Loci (probably the Agouti Locus, a major patterning gene locus in most mammals that works in conjunction with E+) that have genes that have stimulated a mostly black pigment pattern in the presence of the E+. I would love to see the results of a DNA color test on her to see if she is indeed E+/E+.

The calf is most definitely a genetic red and not a black, no matter how dark she turns. When bred to a red bull, she will throw 100% red calves. If she is bred to an Ee/Ee (true red) bull, her calves will likely not go as dark as she is).

Here's a link to a calf born to one of North America's most prolific Dexter herds. You'll see a similar heifer that went from bright red to rather black (I haven't talked to the breeder recently, so who knows how black the heifer is by now). Notice she is rightfully listed as red.

Dark Red Heifer

Hope this helps,
Kirk

PS. Some of what I have stated is genetic fact and some is theory, so I would love to have someone correct me if they have better information.

Posted: **Wed May 16, 2007 6:18 am**

Inger wrote:We've had other calves born brown, that go completely black as they get older.

I assume that these "brown" looking calves of yours had black noses. Some truly black calves do start out rather brownish looking, but they always have black noses. Those with brown noses are dun and the coats stay brown.

Anyone disagree with this? I've done my genetics theory homework but there are lots of other folks with much more practical experience.

Kirk