Genotypic and allelic frequencies of β-casein in cattle in the department of Putumayo

The objective of this study was to identify the genotypic and allelic frequencies of the A1 and A2 variants of β-casein in cattle in dual-purpose livestock farms in the municipalities of Puerto Asís, Villagarzón, Orito and Valle del Guamuez in the department of Putumayo, Colombia. To do this, blood samples were collected from 44 livestock farms and 560 female bovines of the Girolando, Brahman, BON and Gyr breeds. DNA was obtained from peripheral blood and genotyping of the A1 and A2 alleles was carried out by PCR and digestion with restriction endonuclease. Genotypic and allelic frequencies were determined by the simple count method. In addition, the herd was analyzed with respect to the genetic balance condition according to Hardy-Weinberg using the X2 goodness-of-fit statistical test. The predominant genotypic frequency was A2A2 and the allelic frequency was A2 in the Girolando, Brahman and Gyr racial groups. For the BON breed, the frequencies A1A2 and A2 predominated. The bovine populations of the Girolando and BON breeds are in balance, in contrast to the Brahman and Gyr breed populations.