Dexter Genetics - Is there a variance around the world????

[Deleted]

OK my wonderful and fantastic Dexter experts…………….

Question One: Would one expect differences between the base genetics of the Australian Dexters versus the North American Dexters?

Question Two: Was there a unique marker found on the Y chromosome of New Zealand Dexters?

Cheers
Donna

[cddexter]

Hi Lindon, not sure about wonderful, and certainly not an expert. Experienced, maybe...

Difference in genetics. Now that's an interesting one. On the surface, probably, because the US doesn't allow upgrading, and AU started out with semen from two bulls and all sorts of other breed cows. Some bad breed choices were made, imo, so AU got a lot of excess white to start with. You've had to contend with that (think Sheldon triangle). However, since the makeup of English Dexters is a melting pot of genetics, there is no specific breed trait other than our version of chondro that makes a Dexter unique. American Dexters aren't any different. Smaller gene pool, but melting pot, too. So, there might be some slight regional variation, similar to what one would get in closely line-bred or closed individual herds, but I'd think that overall, the animals are pretty similar.

If you want to have a bit of fun, see if the DCAI would be interested in making the dna records available to Michael Bruford at Cardiff U, and ask if he'd be interested in running them through the program Tim used for his PhD, to compare them to the other Dexter populations. This would probably involve $$, but the answer certainly would be of interest.

Either there won't be enough of a difference to matter, which would put a large spoke in the wheel of the 'purists', or there would be a definite difference, which could lead to other research...

I don't know of a different marker on the NZ Y chromosome. NZ used the same Dexter bulls and mostly Red Poll plus some imports from England and North America, partly via AU, so I can't think of anything other than the Bd2 gene, which wasn't part of the original Dexter genetics. Do you have more info?

cheers, c.

[Deleted]

Oh dont sell yourself short C. Everyone here is wonderful, passionate and experts in their own way – which is why I am drawn back to this forum each and every day 

No I don’t have more info. The questions I posted were actually raised by UC Davis to me.

I have been in conversations with them regarding the ability to test for purity/full blood in the Dexters.

UC Davis does offer a Cattle Breed Assignment test based on the probability of breed specific DNA markers being present in an individual’s genome.

The test is currently being expanded to include Dexters.

But UC Davis know there are certain markers found only on the Y Chromosome so its limiting certain aspects of the analysis to male subjects.

Because of Australia’s grade up program UC Davis is concerned this could confound the data making the analysis more challenging and possibly not allow a clear cut result.

So we have offered our 6 bulls for them to use as test subjects. They have 5 of the bulls’ tail hairs and I will be sending the 6th bull (5 week old Bailey) hairs as well.
We know of one bull that has a ¾ grade up as his paternal grandmother (or was it paternal great grandmother…….one of them)

This bull has also sired a son whose dam I (currently) cannot find a grade up anywhere in her much generational pedigree. And the other 3, also I cannot find a grade up anywhere in their Australian lines.

Of course as soon as an import has been stated, I haven’t had the time to search out that animal’s pedigree. And we have UK, USA, Canada and Sth African imports.

So I hope they have a good selection of possibilities to work the testing process out with.

I know it may sound silly for us to be even thinking about this type of testing for Australian lines considering the grade up program, but if it helps the breed world wide – then it’s a good thing.

It will also be extremely interesting to see if a lingering question I have comes to light.

That is, yes we have grade ups, but just how many generations AFTER this occurs in a pedigree will those ‘introduced’ genes disappear? OR do they?

Australia has only used Angus and Jersey (from what I have read) as part of the grade up program. So at least knowing this, may help in the determination of ‘purity/full bloods’ testing requirements for all Dexters irrespective of where they live.

PS: I have to stop writing a book each time I reply......................sorry

[tarsallat]

Australia/New Zealand used anything to grade up. Jersey, Angus, (the most common crosses) but also Guernsey,Red poll, Galloway, Devon, Lowline, Holstein, Murray Grey, Charolais, Limousin, Brahman, Droughtmaster, even shorthorn I think, and probably lots of others as well.

[tarsallat]

That's where they think BD2 came from, the grade up animal from Meadowpark Charles.

[Deleted]

Jun 12, 2013 17:57:06 GMT -5 tarsallat said:

Australia/New Zealand used anything to grade up. Jersey, Angus, (the most common crosses) but also Guernsey,Red poll, Galloway, Devon, Lowline, Holstein, Murray Grey, Charolais, Limousin, Brahman, Droughtmaster, even shorthorn I think, and probably lots of others as well.

Where I have discovered grade ups in pedigrees, there has only been stated either Angus or Jersey. I have never seen another breed listed within an Australian Dexter’s pedigree.

Do you know of a pedigree I can look up that has another breed other than Angus or Jersey?

Never seen one so are very interested in knowing who and what.

Meadowpark Charles had a grade up in his pedigree which was red poll/Jersey, and the discovery of BD2 is still undetermined as to where it came from.

Unless I am reading BD2's appearance in all the wrong places – which is likely….point me in the direction

[Deleted]

Genebo, wouldn't it ever be welcomed. The Legacy database would certainly be as accurate as it could possibly be then. And it may help with bullfinch's undetermination to boot.

While the US didn't allow grade ups, accidents happen and without mandatory parent verification for registration, couldn't the lack of parent certainity pose a small problem as our grade ups?

I really love the idea of this test too Genebo. It's just a shame it's currently only available on the Y chromosome (hopefully only for now), but how wonderful that UC Davis are willingly including Dexters into their research.

yes, I do have a few ideas, love genetics, love science but I don't think I insigated dexter assignment testing, I think it was just good timing with my enquiries.
I know the test results, either waymozilla not be reliable at this early stage but it will be a start at least to hopefully a perfect purity test for Dexters, or at worse, a possiblility percentage.

I'm waiting to hear back from them re baslining etc.

[tarsallat]

The Australian dexter society has the neatest website and searching for all sorts of things are so much fun. Just google Australian dexter society and then they have a spot for animal search. Click on that and you can put in all sorts of things to search for. You can select for halfbred animals and then put in any of the early bulls semen that was sent over to Australia as the sire and click on search. It will bring up the names of all registered graded up animals. if you click on each of the animal names it brings up their pedigree and you can see what the base breed is as the dam. You can specify the year born, or colour, or polled, lots of choices. So much fun. Lots of different breeds used to grade up, not just jersey or angus.

[cddexter]

Lindon: Meadowpark Polly is considered the Bd2 culprit. And, I believe it's assumed (?) that it came through the Red Poll side. Perhaps because Jersey's are so well documented there isn't much left to chance with them. If you want facts on upgrade sources, you couldn't do better than contact Margaret Paynter. She's been involved with all things genetic forever.

The trouble with using any dna from the US or Canada is the lack of parentage verification. There may be some now (Genebo for instance) but he's a relative newbie, and so for that matter, is Judy and her database. There are no guarantees of pedigree accuracy up till dna testing. We were blessed with a number of old owners who didn't have a clue, and just registered everything, no matter how unlikely. Is Davis aware of the foundation genetics project of Michael Bruford at Cardiff U? He was hired by the DCS to find a base genetic for Dexters but was unable to. Judy sent him I think it was 12 samples from her own herd, which he kept as a subset, but they didn't test unique, either. Is something similar not what Davis is trying? cheers, c.

[Deleted]

Thank you for Margarets name C. I will get in contact with her. I have heard her name mentioned a few times now. There's so much I want to know and understand.

I'm not sure if UCD is aware of Michael, I will certainly ask.
It sounds similar. I will have to ask UCD if 'base genetcis' is the same as 'Breed Assignment' sounds like the same if not very similar.

Is there documentation from Michael?

UCD is only evaluating / sampling the Y chromosome for unique markers, is this what Michael had done as well?

UCD would benefit greatly from obtaining a few samples of 'known' (as possibly could be) purity DNA to use as a baseline.
I was thinking of grabbing Judy's expertise in trying to locate available for sale semen which might fit this criteria.
We would be more than happy to purchase straws and have them sent to UCD if this would help them in their search for a purity test.

Judy?
Or someone who may know of such semen?

Cheers Donna

[cddexter]

You wouldn't need semen. Judy has genotypes of her own animals, and of those belonging to others to whom she could apply for permission to share, that on paper appear to descend directly from the 1915 imports. Don't hold out a lot of hope for something different. Those imports were a mixed bag, including animals that were never registered in Ireland or England, but 'would have qualified'. That's why this whole purity thing is such a misnomer. I don't think Mike looked at the Y chromosome specifically, but his paper is available in both long form and 'presentation paper' form. I have both here, but not in a transferrable version. Judy does, as does Patti. You could try either of them. Be prepared for the extensive use of 'could be' 'may be' 'possibly be' assumeds. Actually, with her claims of close ties to UCD, I'd be surprised if Judy already 'could be' 'may be' possibly be' already involved but intends to surprise us with her insider knowledge. I'd check with her first. cheers, c.

[midhilldexters]

Yeah that was probably why Judy had a Wanted add on the British Dexter Board a while back for semen from a certain bull. Great project, hope they can work something out. I agree get in touch with Judy.

Carol K

[jamshundred]

Donna,

<<<I'm not sure if UCD is aware of Michael, I will certainly ask.<<<

Dr. Michael Bruford was professor overseeing the doctoral research project on Dexter cattle of Tim Bray, now referred to as the Cardiff project. Andrew Sheppy, ( Dexter breeder for many decades, committed preservationist, and current President of the DCS) assisted Mr. Bray in the gathering of samples and data. Legacy was very fortunate to be invited to participate and Amercian samples were submitted for inclusion.

The head of UCD-VGL and Dr. Stefanie Oppenheim were the first to receive copies of the Cardiff report when Legacy was given permission to release them. A copy of the report can be read online or downloaded in PDF format from the website: DexterCattleAmericanLegacy.info

The report from the Irish research project is also there and can be downloaded. It is interesting to note for the sake of comparison of the two studies that Dexter cattle in Ireland became extinct and it was not until the 1970's that Dexters were imported to Ireland from the Shadwell herd in England for repopulation, so the Irish cattle have similar bloodline status to some English groups in the Cardiff study.

<< UCD would benefit greatly from obtaining a few samples of 'known' (as possibly could be) purity DNA to use as a baseline. I was thinking of grabbing Judy's expertise in trying to locate available for sale semen which might fit this criteria.<<<

UCD has a sample of every Dexter in America with a foundation pure pedigree that could be located and gathered. It can factually be stated that UCD has samples of the rarest Dexters in the world and would be granted permission by the owner to evaluate them if requested. Those animals come from a herd known as the Colorado herd, original owners and breeders Mark and Marge Davis. They bought their first Dexters in the mid 1964 and began their herd with three cows and one bull. Lady Knight 1187, Lady Debra 1202 and Lady May, 1253 and added a fourth Juletta Dee. Juletta Dee had the least influence on the herd as her descendents were not incorporated back into the herd breedings. The first bull used was Peerless Irish 1214 and in 1976 they began using the bull Brady's Run Challenger. These are the only animals in the bloodlines of the Colorado herd and will trace to the Irish imports. The owners of the herd found it increasingly difficult to maintain the herd and an attempt was began last year to save as many of these animals as possible. The herd was DNA genotyped in 2009 and the samples entered in the Legacy database at UCD-VGL.

Mark and Marge Davis have decreased their herd to just a few animals and if they are able to hang on through the winter they will celebrate their 50TH year as Dexter owners/breeders in 2014. FIFTY YEARS ! !

There is semen in Legacy storage for some bulls from other herds that is kept for the preservation effort but it is very limited in quanity. Hopefully a Colorado bull can be collected in the next year or so.
There are some animals in the English effort to restore their original population animals and I believe there may be at least two bulls collected there so far.

Judy

[jamshundred]

Carol K - - I don't know why you are always so "catty" in remarks relating to me. I've never done you a disservice. If you have any questions you would like answered about me or my interests you can ask me. . I am very open and honest about facts and my opinions. I managed to get a sample from the bull I was seeking and there are updated markers available for anyone who might need them.

Judy

[midhilldexters]

Ya know Judy, it wasn't said that way or meant that way. Maybe you are the one with the issue the way you interpret stuff? You always have to take something and twist it.
If I had had that much interest in why you had a wanted add for semen from that bull I would have brought it up, but I didn't.

Carol K