Variantes genéticas de caseínas y β-lactoglobulina en el ganado Lucerna y su asociación con la calidad de la leche

This study aimed to evaluate the variation in the genes CSN1S1, CSN2, CSN1S2, CSN3 and LGB in the Lucerna breed (LUC). For this purpose, 94 LUC animals and 10 Hartón del Valle (HDV) animals were genotyped using the GGP™ Bovine 150 K chip, which contains four single-nucleotide polymorphisms (SNPs) in the CSN1S1 gene, 14 in the CSN2 gene, two in the CSN1S2 gene, 12 in the CSN3 gene and 11 in the LGB gene. Haplotypes and protein variants of αS1-CN, β-CN, αS2-CN, κ-CN and β-LG were reconstructed. Genotypic frequencies of the major variants were compared between sexes and generations. Hardy-Weinberg equilibrium, wFST and FIS values were assessed for each of the SNPs. LD values and haplotype frequencies for the caseins were estimated and plotted. The CSN1S1*B, CSN2*A2, CSN1S2*A, CSN3*A and LGB*B variants were the most frequent in both breeds. Genotype frequencies did not vary between sexes, and only the CSN2*A2A2 genotype varied between generations. Hardy-Weinberg equilibrium was maintained for all markers, except for one SNP in the LGB gene. The wFST values obtained were very low according to sex (wFST=0.0043) and generation (wFST=0.026). The FIT value was -0.0086. Nineteen CSN1S1-CSN2-CSN1S2-CSN3 haplotypes were found in LUC and eight in HDV with different frequencies. The genetic linkage between the casein genes was low. In conclusion, the genes studied are polymorphic, with a high frequency of variants related to milk production, quality and technological performance. These results can be used in assisted selection programs aimed at improving milk quality and processing traits.