Implications for the use of horse hair roots as a DNA source for microsatellite typing

Hair roots are a very attractive source of DNA for microsatellite-based parentage control of breeding animals. However, unlike blood samples, irregular DNA typing results have been observed in assays utilizing hair follicles. The amount of starting material and DNA preparation method are the crucial factors. In order to improve DNA typing results for horse hair roots, two quick preparation methods and additional purification steps were evaluated. PCR efficiency for each approach was expressed as percentage of samples with complete DNA profiles for 12 horse microsatellites. The lowest percentage (22%) of complete DNA profiles was obtained for samples prepared by the proteinase K digestion method. The best genotyping results (94%) were achieved after phenolchloroform extraction of DNA from samples prepared by the proteinase K digestion method. Direct cleanup of DNA samples with an ethanol-sodium acetate mixture gave comparably good results of microsatellite genotyping (91%). DNA preparation from hair roots with proteinase K digestion followed by DNA purification with ethanol was chosen as the most efficient approach for horse DNA typing under parentage testing.