How Important is DNA Parent Verification?

[Donlin Dexters]

I often wonder, as an aussie where Dexters are part of a grade-up program but DNA PV has been mandated as part of teh Registration process for over two decades now, just how accurate are American Dexter Registration records?

DNA parent verification is and never has been mandatory for registrations nor has or is this been commonly practiced amongst American breeders.

Now dont jump on me  I absolutely totally support everything that is Legacy

........but I do wonder what results will come to light if one day there is a Dexter Purity Test available.

The below I found extremely interesting and the bolded part is a little disturbing as it refers to the results probably being lower than what could actual.


Taken from an article: Increasing Pedigree Accuracy with DNA Parent Verification - located here: sbts.une.edu.au/pdfs/DNAParentVerification.pdf)

An interesting case study into how easily errors can occur in pedigree recording even in a herd following best practice guidelines, was demonstrated in the Beef Information Nucleus Progeny Test Program conducted by the Australian Limousin Breeders Society. To ensure accuracy of sire information, the sires for all calves from the first joining in 2011 were checked by DNA profiling and verification. The parentage verification highlighted a number of pedigree recording errors including:

• The wrong straw of semen was used or the sire recorded incorrectly for three calves during the AI program.
• Four calves were incorrectly assigned to the back up bull whereas they were actually sired by the AI sire.
• Human error occurred during the data entry for another three calves.
• Two calves born on the same day had clearly swapped mothers at birth.

In total, 12 of the 227 calves (5.3%) were given incorrect sires when the pedigree information was collected. Considering the Limousin Progeny Test Program was following best practice guidelines, it is probably indicative of the lower level of pedigree errors occurring across the registered cattle industry and highlights the benefit of DNA parentage verification.

[lakeportfarms]

The link doesn't work for me, but it looks like an interesting article.

The ADCA still doesn't require parent verification for females or on the dam's side of the pedigree, and so there probably continues to be errors and probably even some intentional deception going on. I could go on Craigslist right now and buy any number of grade "Dexter" (or even Angus) heifers or cows for a much lower cost than a registered Dexter, breed them to my registered Dexter bull, select one of my other registered Dexter cows that had a bull calf that had been steered so it didn't look like she calved that year, then genotype the subsequent calf getting "Sire qualified" status listing the registered cow as the dam, no parent verification of the dam necessary for either heifer or bull calf.

Perhaps somebody did the same before me, and I was an unwitting buyer...hard to say however it is less likely to happen if you have a good eye and knowledge of the phenotype of what a Dexter is supposed to be. I am often amazed when I see some photos of what clearly look like Angus traits on "Dexter" cows or bulls, and the supposed experts on confirmation, all things Dexter, etc... rave over how great the animal looks and how it will improve their progeny, etc...  Sorry folks it may be a beautiful bull or cow but it looks more like an Angus than a Dexter...

I think the chances of AI error are pretty low compared to more commercial breeds. Usually there aren't 20 different Dexter AI sires in somebody's tank. That said, there are probably a lot of small breeders who have bull calves that don't steer them soon enough, or at all before they are butchered. So the chances of having a young bull sneak in and breed a cow are pretty great. My thoughts are that that is where the majority of the inaccuracies are.

[Deleted]

I dont know how there could ever be a purity test. what would you judge it against. There are far to few dexters that dont have an upgrade in them and the ones that dont are all very closely related. I would hope that no one would have done the deception that Hans describes could be done. I am guessing the bull calf option probably has happened many times. In most cases those raising registered dexters would not have had other breeds with them. The bull calf in most cases would be closely related likely with the same descendants. 
Yes I know what you are talking about in the case of dexters that do not look very dexter. I think this is from what has come into the breed from the upgrades and then compounded by people selecting for those traits. Not only the angus look as you say but I also see a lot of dexters that look Like Devon.

[Deleted]

Hans can you explain the difference you see in the type
of Dexters you explained? Our Lucy sure has a beefy look
to her but sure has the look of most Dexters I view. She
has the curly head hair and on her upper forward body.
If I can ever load a picture here I will. Also her calf
is a 1 1/2 week old and both are doing very well.

[jamshundred]

With the technology available and reasonably priced I think it is important.  I have also been supportive of it being voluntary in the past for farms that have only one bull on the property.  Even though there are many claims of "bulls jumping fences", I don't know how this would go completely unnoticed by an owner.  The bull has to jump back over and leave unnoticed. .   and anyone of my bulls would raise such a racket with a competitive intruder . . . . I'd know there was a problem.   In any case where an owner has a doubt. . . they should be responsible and test.

I believe that any breeder who has two or more breeding age bulls in their herd should be required to mandatory DNA type and parentage verify.  I've corrected a couple of errors that occured in years before I began genotyping and I was the first Dexter owner in the US to DNA test and maintain a parentage confirmed herd.  I think Gene was the second one.

Hans is correct. . . . doing bulls is not sufficient.  I posted a case some weeks ago where a bull qualified on a case where a herd that had not been managed was testing to sort out the identities and parentage.    When a possible dam was submitted UCD ran additional markers ( something they do automatically anytime there is one exclusion or a question on a case - and I know of no other lab that does this) not only did the dam not qualify, but the additional markers disqualified the sire.

I spent years working on one herd that has public pedigree problems.  It began when I purchased a cow and her pedigree showed she had three calves in one year. . . not triplets.  There were several cows in the herd with registration errors of the same type.  The owner was loading his trailer to go to an AGM and suffered a fatal heart attack.  The family didn't have a working knowledge of the herd and ADCA personnel tried to help the family by registering the calves, some of them obviously inaccurately.   I tried to type every animal in the herd and straighten it out. . . not only for the cow I purchased,  but for the breed, the registry, and other owners whose animals were also mis-registered but there were samples of necessary animals I could not get.  That entire mess was fixable.   Most of the issues that are known, imo, are still Dexters, just the wrong identity for parentage.  The DNA markers in this breed have very little diversity so an outcrossing should always turn up an odd marker.  

I think that early breeders did a remarkable job with registering correctly.   It seems to me the issues are more modern. . . . . .  when Dexters became more popular and populated and the polled gene came in.   Many of the animals that look like other beef breeds . . . . . ARE . . . . to a large degree.  You cannot have four outcrossings in 10 lines without the traits of those beef animals coming along for the ride.

There IS a test at UCD that will show other breeds in a genotype.  I owned an animal whose sample I will have tested one of these days when the $100 isn't more important to be used for other things.
Judy

[lakeportfarms]

Blessings Farms it's a bit difficult to describe without photos, and I hesitate to copy photos from other places and put them here with my opinion. My wife ran across this ad on Craigslist, do you think this looks like a Dexter Bull?

houston.craigslist.org/grd/4684029261.html

Or this one?

www.dexterbeef.com.au/rawlings-blueprint.html

or some of the photos of the bulls Judy has posted here and on the Facebook Dexter Cattle Historical page?
That's all you really need to see.

Even with faces only you can often see differences...see the photo on the front of the Dexter Bulletin. In my opinion the Dexter should have a more triangular shaped dished face with a wider forehead, for example.

You'll find many of the breeders who have "upgrade" animals in the pedigree will talk at great length about their classification results. As I said, they may be beautiful bulls or cows, but they don't fit the Dexter phenotype in some important areas. To my knowledge, the classification scoring does not take into account; or if it does, it does not put much importance into, "does the bull or cow fit into the breed description for either height or weight of the Dexter breed". Most of these animals would be severely marked down if either or both of these factors was considered with any kind of importance.

[Donlin Stud]

Whoops - sorry about the above link - I had a bracket on the end of the URL:

Here try this one:

sbts.une.edu.au/pdfs/DNAParentVerification.pdf

[Deleted]

Thanks Lakeport no more explanation needed.

[genebo]

The only thing that can give the utmost integrity to a geneological registry if full DNA parentage verification.

This is only effective as far back into the registry as the parentage verification reaches.

I a system that charges to have parentage verification done, I think it would impose a harship upon some members, and should not be made mandatory. Instead, it should be provided to the members as a service.

The Legacy Dexter Cattle Registry has been quietly doing that for quite some time. You pay $25 for a registration and you get a parentage verification at ne extra charge.

That proves that it's not impossible to do.

Just an aside: In a conversation a few years ago, an English Dexter breeder stated that he no longer registered ANY of his Dexter cattle. The extreme costs of the required testing necessary for registration had taken him out of the game. Only a year or so later, he was crossing his Dexters with beef breeds. We here in America need to heed the example of what can happen to our own Dexters if the cost of registration is raised too high.