Comparison of molecular methodologies to indentify the kappa casein gene in Holstein cattle

Objective. Compare the PCR-RFLP's and PCR-SSCP's molecular techniques in order to identify the allelic variants of the kappa casein (CSN3) gene in Holstein cattle in Nariño-Colombia. Materials and methods. 50 female Holstein cows were randomly chosen and 5cc of blood samples were obtained from the animals´ medium coccygeal vein. The samples were stored and preserved in FTA® cards for further lab analysis. and were analyzed in the molecular laboratory. The DNA was amplified through PCR using specific primers. The changes in the single strand of DNA were visualized in 12% polyacrylamide gels, whereas the RFLPs were obtained through digestion with three restriction enzymes and visualized in 4% agarose gels. Results. The PCR-RFLP's technique was useful to detect punctual mutation and to identify a greater number of alleles which contributed to a better estimate of the genetic diversity measurements on a selected populations, because it avoids the over estimation of values in allelic frequencies. On the other hand, the PCR-SSCP's technique was simpler and cheaper, ideal for research where there is no previous genotype information on cattle populations or in studies that are limited by budget. Conclusions. Both evaluated methodologies are molecular tools which contribute to the design of selection procedures on dairy cattle because they correctly identify the alleles of CSN3 gene. The difference lies in the cost and the number of identified variants.