Frecuencia génica y genotípica de los alelos A1/A2 de Beta caseína en la descendencia, producto del cruzamiento de sementales A2A2 con hembras bovinas

Abstract

Caseins constitute 80% of milk proteins, with β-casein (CSN2 gene) being particularly prominent due to its A1 and A2 variants. The A2 variant is of growing commercial and health interest because of its higher digestibility in humans. The general objective of this research was to analyze the frequency of A1 and A2 genotypes in cattle resulting from the selective crossing of A2A2 bulls with multiracial females in the province of Azuay, Ecuador. The ARMSPCR molecular technique was employed using DNA extracted from hair follicles of 80 specimens. The analyses allowed the identification of all three genotypes, with a clear predominance of the A2 allele (71.87%) compared to the A1 allele (28.12%), and a genotypic frequency of 51.25% for A2A2, 41.25% for A1A2, and only 7.50% for A1A1. It is concluded that the use of A2A2 sires is an effective strategy to increase the frequency of the desired allele in the progeny, facilitating the transition of herds toward A2 milk production within the Ecuadorian context.