The Effect of the Genotypes of the <i>CSN2</i> Gene on Test-Day Milk Yields in the Slovak Holstein Cow

Abstract

The aim of this study was to analyze the polymorphisms of the beta-casein gene and describe the association between the beta-casein genotypes and milk production in high milk-production Slovak Holstein cattle herds. Genomic DNA was isolated from the hair root samples of 1478 cows using a commercial column kit. The detection of the specific alleles A1 and A2 of the CSN2 gene was carried out using three molecular-genetics methods, including the TaqMan allelic discrimination assay, ACRS-PCR and SBE primer extension technology. The results of the molecular-genetic analysis were used for calculating the genetic structure in the analyzed population. All three genotypes, including A1A1 (5.28%), A1A2 (37.08%) and A2A2 (57.64%), were detected. The frequency of the allele A1 was 23.82% and the allele A2 was 76.18%. The statistical analysis and data preparation were performed using the SAS 9.2 Enterprise Guide 4.2 software. A general linear model (GLM) and the least squares means adjusted for multiple comparisons were used. A significant positive effect of the beta-casein genotype A2A2 on protein in kilograms and partially for the protein content in Holstein cows was found. Only the highest the least squares means for the fat percentage was found for the genotype A1A1 compared to the genotype A2A2. This can be considered a slightly negative trend.

Keywords

• breeding
• Holstein cattle
• A2 milk
• <i>CSN2</i> gene