Written By Ron Metz President, PDCA
By and large, the initial feedback on the DexGen genetic recovery program was positive. This indicates to me the membership is in favor of implementing such a program to allow unregistered Dexter females into the PDCA registry by means of strict evaluation and DNA testing. There were some members who voiced concerns about the accuracy of the UC Davis VGL breed test and if DexGen would allow upgraded females into our registry. To find answers to those questions, I contacted the lab. I was told they had a breed test which could identify markers for the presence of 15 different breeds in a DNA sample. To answer the question of accuracy, I was directed to contact Shayne Hughes, Associate Director of Administration and Information Technology. Upon doing so, Shayne said he would have to consult with Dr. M.C. Penedo who was responsible for that type of testing.
Dr. Penedo said “the current breed test does not have the necessary accuracy to prevent all upgraded cattle from passing the purebred Dexter status. Since the test is based on 20 STR markers, the genotype of some upgraded cattle will have a high probability value in Dexter.” Dr. Penedo went on to say she doesn’t know the expected failure rate of passing the test since she hasn’t done much on this type of validation with controlled cases. Her recommendation is a denser SNP test may be better suited for the PDCA’s intended program. SNP based breed testing identifies over 200 markers rather than the 20 that UC Davis VGL’s current breed test identifies. Dr. Penedo has recently retired. Shayne explained they are actively recruiting a person to lead their research and development section to take Dr. Penedo’s place. Their ability to address requests such as ours should improve in the future.
What does all this mean for DexGen? I believe DexGen is a viable program our members will benefit from. Therefore PDCA will continue development of the concept. To achieve the goal of preventing upgraded Dexters into our registry, we need to seek the services of a lab that utilizes highly accurate SNP testing. I will be in contact with labs that offer this type of testing and discuss the DexGen concept with them. In the meantime, DexGen implementation will be put on hold until highly accurate SNP testing can be secured. I want to thank Shayne Hughes and Dr. Penedo for their time answering my questions.
I also want the membership to continue offering feedback on DexGen. I encourage all PDCA members to voice their opinions either for or against this program.
Please contact me, Ron Metz, at firstname.lastname@example.org