The Human Genome Project should receive partial credit for giving us the technological advancement and innovation necessary to conduct widespread genetic research.
The project, which completed the first sequence of the human genome, finished in 2003. This massive undertaking led to the development of rapid and automated genetic sequencing. It has trickled down into many other aspects of science and given rise to the availability of commercial genetic tests. More genetic tests are available for animals than ever before.
Four main types of genetic testing are available — parentage, ancestry, specific traits and diseases — and all four types involve the same basic steps.
Read Also
Dry summer conditions can lead to poor water quality for livestock
Drought conditions in the Prairies has led to an decrease in water quality, and producers are being advised to closely monitor water quality for their animals.
Owners collect a biological sample. Genetic tests for cattle and horses require 20 to 30 hair samples that contain the white hair root (follicle). Hairs are stored at room temperature in an envelope marked with the animal’s identifying information, such as name and tag number. For dogs and cats, saliva swabs are the sample of choice.
The biological sample must be then shipped to the testing laboratory for the requested test. At the laboratory, technicians will process the sample to extract the DNA (genetic material) and then sequence the sections of interest. These are then compared to known genetic sequences. No test is 100 per cent accurate, so results are often given as a percentage or probability.
The first main type of genetic test is used to determine the parentage of an individual animal. Some purebred registries require this. It is also useful for herd breeding situations or if there is any uncertainty of the sire or dam.
For instance, a purebred herd with multiple bulls turned out during breeding season may require genetic confirmation of which bull sired which calves.
It is also applicable to situations where artificial reproductive technologies such as embryo transfer and frozen, shipped semen have been used.
The testing requires submission (or the DNA data) from potential sires and dams and then eliminates or rules in the potential of each to be the parent.
The second main type of genetic testing is ancestry analysis. This type is more to satisfy a person’s curiosity rather than to direct management or breeding decisions.
An interesting test for horses is offered by Texas A & M University. The horse being tested is compared to a panel of 50 known breeds and assigned to the top three most likely breeds of origin. Similar commercial tests are available for dogs and are popular with mixed-breed dog owners who wish to know a little more about their pet.
The third category of tests is for specific traits. In cattle, this includes tests for milk protein types, coat colour and polled vs. horned. Horses can be tested for coat colour.
Finally, genetic tests for specific diseases are now readily available. These are especially useful for directing breeding decisions in purebred animals. Diseases that are the result of a single gene change are the most amenable to genetic testing.
Using the results, breeders can select mating pairs to eliminate or reduce the risk of the disease occurring in offspring.
Complex diseases that involve multiple genes aren’t easy to test for or eliminate. In cattle, a few diseases for which tests are available include freemartins, progressive ataxia in Charolais cattle and dwarfism.
The American Quarter Horse Association is an interesting example of an organization that has embraced genetic testing as part of its horse registration process. It has specific genetic testing requirements, including parentage verification and a health panel.
The health panel includes screening for six genetic diseases including the muscle conditions common in this breed.
All breeding stallions need to have these tests done through the association in order for their foals to be eligible for registration.
A final genetic test worth mentioning is meat analysis. This has interesting applications for quality assurance and consumer confidence in meat products.
It is an interesting time now that genetic tests are widely available. As more diseases and traits are linked to genetics, we can expect even more tests to become available. These can be used to direct breeding decisions and improve our herds.
