Reference Library

Genetic Tools for the Texas Longhorn Breeder DNA Testing
New Tool in Determining Proof of Parentage
By Keith Fry, Chairman of A.I., Embryo Transfer & Blood-typing Committee

The ability to determine the parentage of any animal to be registered is of utmost importance to any Herd Registry, including the TLBAA. Before any bull can become Al certified in the TLBAA registry, the applicant must be able to prove who was the sire and dam of the bull.

In the past, blood-typing has been used to determine parentage, and it served the TLBAA well. Now there is a new method which is much more accurate, and so much easier to use. It is called DNA fingerprinting. I will not try to explain what the initials DNA stand for; it's hard enough to pronounce, let alone spell. However, anyone who watched the news of the O.J. Simpson trial last year already knows more about DNA than they did a few years ago.

Listed below is a summary of the many advantages of DNA testing as opposed to blood-typing an animal in order to prove, or even to establish proper parentage. You will find it is amazingly accurate, to the point of being almost scary. Undoubtedly, it will make for an extremely accurate registry. We are fortunate to have such a tool at our disposal.

I. Positive parentage determination.

2. Multiple sire mating.

3. Embryo screening.

4. Permanent animal identification.

5. Precision results- no chance of false positive results.

6. Test specimen results-blood, semen, muscle, hair, etc.

7. Stability - testing can be done at any age.

8. Early identification-embryos at embryo transfer stage.

9. Cost effective-same as blood-typing.

10. Embryo sexing ~ can determine sex of embryo.

II. Stolen animals -has been used in a court of law to prove rustling.

At this point, the greatest advantage to DNA testing is in the area of accuracy. If enough probes can be used in a sample, the accuracy can be as high as 99.9%. The margin of error is almost an insignificant figure when compared to that of blood-typing. Although blood-typing does have a high level of accuracy for use in excluding animals as potential parents of offspring, it can only qualify animals as a parent or offspring, showing only that an animal could be a parent or offspring. On the other hand, DNA testing is highly accurate in both excluding potential parents and in identifying the actual parent.

Another great advantage of DNA testing over blood-typing is in the area of convenience. Almost any cell sample can be used, such as blood, semen, meat, milk, hair (not only from living animals, but deceased as well), and including embryos.

Many cattle and horse registries are presently using DNA testing and have had excellent results. At the TLBAA annual meeting in 1995, the membership approved a by-law change that allowed this registry to phase in DNA testing, thus keeping us in step with other progressive, reputable registries.