DNA Testing

Dr. Gerald Hauer
Reprinted from The Tracker, Volume 3, Issue 11, December, 1999, pages 6-8.

Summary

Using sophisticated technology, labs are using samples from a variety of tissues to harvest DNA. The genes on the DNA are compared to see if the animals are related and this can be used to confirm parentage and to establish pedigrees.

DNA Testing

DNA testing to verify parentage has been used in the elk industry for a number of years. The need for testing has increased in the last few years because artificial insemination has become a popular method of improving genetics in an elk herd. Considering their value, it is important to be able to prove the parentage of individual animals. With the high prices being paid at bison shows, there may soon be a demand for parentage testing in this species as well.

DNA testing uses sophisticated technology that compares the genetic material of animals to determine if they are related as parents and offspring. All animals carry their genetic material in genes, which are located on tiny strands of DNA in the nucleus of almost every cell in the body. When an animal is conceived it receives one set of genes from each parent and the combination of these genes determines the characteristics of the individual (size, color, etc). Using special equipment and state of the art technology, laboratories have been able to identify groups of genes or "markers" on the DNA strands. By determining which markers the offspring carry and comparing them to the markers of the potential parents, labs can verify the accuracy of pedigree records and sort out questions of parentage.

The efficacy of DNA testing for parentage verification depends on the amount of genetic variation present in the species of interest. The more genetically diverse the population, the more informative the tests and the easier it is to determine the parentage. The farmed elk population in North America has less genetic diversity than other species like cattle, horses, deer and bison and for this reason, DNA tests are not always definitive in elk. Occasionally, even when testing for as many as 20 markers the labs cannot exclude one of two possible sires (or dams) if they are closely related. If both the bulls (or cows) are genetically compatible with the offspring, the test results provide no indication as to which one is the true parent. With the limited number of markers available for elk, it is not always possible for laboratories to solve every case presented to them.

The best results are obtained when the lab is supplied with samples from all the animals involved. When they are provided with samples from all the potential sires and dams of an elk herd, they should be able to accurately identify the parentage of about 90% of the calves. The remaining 10% of the calves will have more than one sire or dam identified as a potential parent. If the adults are closely related, the efficacy of the test decreases. For example, if two related bulls (brothers) are potential sires, it will more difficult to sort out than two completely unrelated bulls. The accuracy will also go down if only part of the genetic information is provided. For example, if samples are only taken from the calves and sires and not the dams, the lab has less information to work with and therefore will be less able to provide solutions to cases.

DNA can be extracted from many different samples from the body. The samples that are routinely used by labs are blood, hair roots, and semen. These are easily obtained and easy for the lab to analyze. In special cases tissue such as bone, teeth or velvet antler can be used but the DNA is harder to extract and therefore the labs charge more for testing these samples.
To increase the accuracy of the tests, more genetic markers need to be identified. For now we must understand the capabilities of the labs and work with them in order to obtain the most accurate results.

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