Prevalence of DGAT1 K232A polymorphism in grazing Holstein cows

Abstract

Introduction. Determining of the K232A polymorphism, in the exon 8 of the acyl-CoA:diacylglycerol acyltransferase 1 gene (DGAT1) genotypic frequencies in dairy cows, and the evaluation of its deviation from the Hardy-Weinberg equilibrium, could be an indirect genetic selection footprint of animals that were selected for improved milk fat content phenotypes. Objective. To determine the prevalence of the K232A DGAT1 polymorphism in Costa Rican Holstein cows. Materials and methods. A total of 500 Holstein cows from 50 farms in three provinces of Costa Rica (Alajuela, Cartago, and San José) were sampled from October 2018 to March 2019. Blood samples were taken from coccygeal vessels. Samples were transported under 4 ºC from farms to the Biology School Laboratory of the University of Costa Rica, where DNA extractions were performed. The K232A DGAT1 polymorphism determination was performed through real time quantitative polymerase chain reaction (RT-qPCR), using specific primers. Results. The genotypes of 15 samples could not be determined due to sample limitations. The frequencies of the AA, KA, and KK genotypes for the remaining 485 cows were 54.6%, 38.8% and 6.6%, respectively. There was no deviation from the Hardy-Weinberg equilibrium (chi-square = 0.03; p > 0.05) in the overall population. Conclusion. Random mating between animals for the DGAT1 polymorphism has occurred in Costa Rica.