I'm confused...

[ittybittyfarm]

I'm really confused as to what DNA/Parentage/Genotyping testing is.

Could someone please (in a very basic fashion) explain the differences in these?

My thought is DNA testing will verify Dexter DNA (i.e. 100% pure). Parentage will confirm the dam & sire. Genotyping??? Not sure, maybe all of the Chrondo, PHA type of testing?

Am I right on this? And then how do you do parentage testing if you don't have access to the sire? Sorry to sound like an idiot...

[dexterfarm]

No,dna testing at this point will not confirm that your dexters are 100% pure. The parentage genotype is a set of recognized dna markers. that when compared to the markers of the sire and dam are used to prove or disprove that the sire and dam of record are correct.

testing for PHA or chondro looks at 1 specific marker for each that tells you weather or not your dexters carry that gene or not.

[Julie]

Genotyping and parentage verification are the same thing for the average Dexter owner. The genotype is compared to the calf's mom and dad's genotype to confirm parentage. It eliminates the "who's yo daddy?!?" question. Additional DNA testing can be done for other genetic traits of interest including PHA, chondro, A2 milk, red and dun coloration, and polled.
The more tests you bundle together, the cheaper they get. Right now, I think the best deal is through Legacy (testing done at UC Davis) If you genotype with Legacy, your cow is entered into the Legacy registry, which is promoting genotyping. As genetics discoveries evolve, there could be a great benefit to the Dexter breed to have all of these genotypes stored at UC Davis. Who knows? Meanwhile, it is, in my opinion,cheap insurance for proving you are selling the cow you say you are selling.

[kansasdexters]

ittybittyfarm,

Parentage genotyping is a DNA test that is done to determine a set of microsatellite markers on an individual animal. If the sire and dam have been parentage genotyped, then the offspring can be parentage genotyped and its markers can be compared to those of the sire and dam. If the offspring's markers "match" those of the sire and dam, then the offspring can be "Sire Qualified, Dam Qualified". If there is a mismatch, then this comparison will indicate "Sire Excluded or Dam Excluded" and another sire or dam can be tested and compared until there is a match and the correct sire or dam is determined.

If the sire has not been tested and a sample is unavailable, then the best you can do is to parentage genotype the dam and the calf. The calf can then be "Dam Qualified" and the Sire will be indicated as "Sire Not Typed" on the report.

Since the ADCA already requires all sires to be parentage genotyped and "on file" at Texas A&M, before any calf born after December 31, 2009, can be registered -- most bulls are already "on file". By parentage genotyping the calf, and comparing its genotype to that of its sire, the calf can be "Sire Qualified". If the dam of the calf is also parentage genotyped and "on file" at Texas A&M, then the calf can also be "Dam Qualified".

These tests are done to assure that the correct sire and dam are entered when an animal is registered.

Patti

[ittybittyfarm]

Thank you for all of your helpful replies. As far as you know, is this information shared internationally? I'm Canadian, but have US semen for this summer (wow that sounds strange!!). The CDCA suggests using Igenity for testing; however UC Davis tests Canadian animals as well. I'm not sure about Texas A&M. If the sire is listed on ADCA and I put his name & number as sire can my calf be matched or does that go against the privacy issues?

[kansasdexters]

ittybitty,

If the AI bull that you plan to use has been parentage genotyped and is "on file" with the ADCA, then his genotype is in the Texas A&M database. If you have the calf's genotype done at Texas A&M, then its genotype can be compared to that of the sire and it can be "Sire Qualified". If you have the dam parentage genotype tested at Texas A&M, then after the calf is parentage genotyped, his genotype can be compared to that of the dam and he can be "Dam Qualified".

Alternately, if the CDCA requires the parentage genotype to be done at a specific lab, then you can arrange to have the AI bull parentage genotyped at the designated lab by submitting a straw (or partial straw) of the semen. Then the bull's parentage genotype will be in the database that you need for complying with the CDCA requirements (if it isn't there already). Check first, because the seller of the semen may be able to provide this information to the lab, per your request, and save you the cost of testing the bull's semen.

In order to parentage verify a calf, its sire and dam genotypes must be in the same database as the calf's genotype test result. Sometimes, if an animal has been tested at one lab, the test results can be transferred to another lab (by request from the test owner).

Anyone can test a straw of semen from an AI bull that they are using, in order to get the parentage genotype markers of that bull into the database where they will be utilized.

Patti

[marion]

Ittybitty, the US bulls available for AI in Canada should have their DNA already on file at SRC-GenServe. Check with CDCA Secretary Ron Black or the seller of the semen. I believe the Igenity lab was recommended for the PHA testing, although they have now added UC Davis as also being acceptable..marion