DNA Testing for Dexter Cattle: An Update

John Potter, ADCA Genetics Committee

updated 1/1/2004

Two additions in 2003 to the DNA testing program for Dexter cattle provided the incentive for writing this article. This update lists the tests that are now available and gives the basic information about each of them. In an ideal world a single company would conduct all of the tests that we need. In the real world- especially remembering the fact that Dexters are a minor breed- we must accept the fact that three different companies, each with its own application, conduct our four tests at this time. Applications for all of the tests are available upon request from John Potter by email (jpotter@remc11.k12.mi.us), by telephone (269-545-2455), or by USPS mail (2524 W. Elm Valley Road, Galien, MI 49113). When requesting an application, please specify whether you want it sent by email (MS Word document attachment), USPS mail, or fax, and provide the information relevant to your preference. DNA for all of these tests may be obtained from hair, semen, or blood. All of the applications contain the instructions for using hair and semen as the source of DNA. Since using blood as the source of DNA tends to be considerably more complicated and expensive, we have not included instructions for using blood on all of the applications. If you wish to use blood, please contact me for the details. Since the testing companies’ procedures for packaging, labeling, and sending samples vary, please read each application’s instructions carefully. Each application contains the mailing address of the company that conducts the test. Complete applications and full payment accompanying the samples are prerequisites for all of the tests. If you have any questions about the instructions and procedures, feel free to contact me. The following chart contains the basic information about the four tests that are now available. Details about the basic information are given in footnotes below the chart.

name of test	purpose(s) of test	test provider	cost per sample in US dollars	results sent to
Red Factor (RF)	1. registration^1 2. carrier identification^2	Genetic Visions (Wisconsin)	$40	breeder & ADCA^3
Dun	carrier identification^4	Agrigenomics (Illinois)	$22^5	breeder only^6
Chondrodysplasia (Bulldog Gene)	carrier identification^7	Agrigenomics (Illinois)	$35^8	breeder & ADCA^9
DNA Genotyping	1. ID record for AI bulls^10 2. parentage verification^11	ImmGen (Texas)	$28	ADCA only^12

¹In order to register a Dexter as red, it must be tested (DNA verified) as red unless it is the offspring of a registered red sire and a registered red dam. If both parents are registered reds, then testing is not required. Please refer to the article, “Color Genetics and Registration of Dexters,” that begins on page 22 of the 2003 ADCA Membership Directory. The article also appears on the ADCA website.

²A breeder may wish to test a black or dun animal to determine if it carries a hidden red gene. (A black or dun animal that has a verified red parent does not need to be tested: It carries a hidden red gene.)

³If the test result is needed for registration of the animal (See #1), then the breeder must sign and date the Release to ADCA on the application. Photocopies of reports furnished by breeders are not accepted for registration purposes.

⁴A breeder may wish to test a black or red animal to determine if it carries a hidden dun gene. (A black Dexter may carry one hidden dun gene, and a red Dexter may carry one or two hidden dun genes.)

⁵If the Dun test is requested from the same sample as the Chondrodysplasia test, then the cost for the Dun test is $10/sample added to the cost of the Chondrodysplasia test. Please complete the application accordingly.

⁶If you wish to have only the Dun test carried out, do not sign and date the Release to ADCA on the application. If both tests (Chondrodysplasia and Dun) are requested from the same sample (See #5), then both tests’ results will be sent to the ADCA Registry Office if the breeder has signed and dated the release.

⁷Mating a carrier bull to a carrier female has a 25% probability of producing a bulldog calf, a 50% probability of producing a carrier calf, and a 25% probability of producing a non-carrier calf. Mating a carrier of either sex to a non-carrier of the opposite sex has a 50% probability of producing either a carrier calf or a non-carrier calf but no chance of producing a bulldog calf. Mating two non-carriers produces only non-carrier calves: no carrier or bulldog calves. Please refer to the article about chondrodysplasia that begins on page 25 of the 2003 ADCA Membership Directory.

⁸If eleven (11) or more samples are submitted at the same time, the cost per test is $28.

⁹As of January 1, 2004, no requirement exists for the notification of the ADCA Registry Office regarding the chondrodysplasia carrier or non-carrier status of any Dexter. However, breeders may request that Agrigenomics send their results to the ADCA for the record by signing the Release to ADCA on the application.

¹⁰Beginning January 1, 2003, the ADCA required that the DNA Genotype of all bulls used for out-of-herd AI be on file in its Registry Office before calves sired by those bulls can be registered. While any AI bull whose blood type was on file in the Registry Office prior to January 1, 2003, is exempt from the DNA Genotyping requirement, the person who sells semen from that bull is encouraged to request DNA Genotyping for the sake of future reference or parentage questions.

¹¹DNA Genotyping can be used to verify the parentage of an animal provided all appropriate DNA is submitted for analysis. Contact John Potter if you have questions about this option.

¹²The service agreement between ImmGen, Inc. and the ADCA for DNA Genotyping stipulates that ImmGen will report the results of their services to the ADCA only. If you wish to have a copy of the report, please request it from the Registrar or from John Potter.