The two alleles of the foal are compared with those from the dam and from the sire, for each of the 17 markers tested, to ensure that one of each pair has indeed come from the dam and one from the sire.
Steps 1-3 result in the production of the individual animals DNA profile, which can then be used for identification or for use in parentage verification. Step 4 is the process of parentage verification, and this test is more than 99.9% accurate. Below is an example of a parentage report for 5 of the 17 microsatellites. The abbreviations across the top row are the names of the microsatellite markers. In the columns below are the 2 alleles present for that marker in the foal, the dam and the sire.
HTG4 ASB2 ASB17 HTG10 LEX33
Foal KK KR NR LM MQ
Dam KO PR LN LL OQ
Sire KL KP RR MN LM
For each marker you can see that one allele has come from the dam and one from the sire. For example, for the microsatellite ASB2 the foal has the alleles K and R. R has come from the dam and K from the sire. For parentage to be verified there can be no mismatches at any of the 17 markers. Equine parentage laboratories worldwide use the same base set of 12 markers, under the recommendation of the International Society of Animal Genetics, so that exchange of information can take place between laboratories and breed societies in different countries. This means that horses don’t have to be retested when they travel internationally, and when imported semen is used it can be accompanied by a DNA profile for use in parentage reporting for any offspring.
Sometimes the results produced are not as expected– there will always be surprises when dealing with horses! Some of the scenarios we see where there are mismatches between foal and/or dam and sire include mares swapping foals in the paddock, and stallions that should not have been with a particular mare using all sorts of devious means (sometimes seemingly impossible) to mate with said mare. Then there are the cases involving human error – mares can be misidentified, transcription errors can occur filling out the paperwork, and hair samples can be put in the wrong envelopes. But with DNA technology and some old fashioned detective work we can now reach a conclusion on the vast majority of these difficult cases. It must be remembered that we can only produce parentage reports for a foal if we have the DNA profiles for the dam and sire on the database. For this reason it is extremely important to test all breeding stock (or possible breeding stock) as soon as possible.
Every year we see a number of cases where foals cannot be registered because the dam has died before she has been DNA typed
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