Genetic differentiation of Simmental and Red-and-White Holstein breeds and their crossbreeds

The enhancement of breeding efficiency in farm animals largely depends on genome mapping and comprehensive genetic monitoring, which integrates tests to evaluate breeding material. Genetic markers play a pivotal role in identifying genes associated with productive traits. The study focused on cattle of various breeds (Simmental, Red-and-White Holstein) and their crossbred offspring (F1, F2). Blood samples were collected from the jugular vein using heparin, plasma was obtained via centrifugation, and erythrocytes were washed with saline solution. The primary method was electrophoresis of proteins and enzymes in a 13 % starch gel. Five polymorphic loci were analyzed: transferrin (Tf), amylase-1 (Am-1), ceruloplasmin (Cp), hemoglobin (Hb), and purine nucleoside phosphorylase (PN). Results were processed using the “BIOSYS” software. Comparative analysis revealed differences between crossbreds and parental breeds. In the F1 group (1/2 blood share), the Tf D2 allele frequency was 0.646 (closer to Simmentals at 0.516), driven by a high proportion of Tf D2D2 homozygotes (39 %) and Tf AD2 (22 %) and Tf D1D2 (20 %) heterozygotes. The Tf E allele was rare (0.012 in F1), with no Tf EE homozygotes detected. In F2, the Tf D2 frequency dropped to 0.480, indicating a leveling of genetic structure. Meanwhile, the low Tf E frequency in crossbreds suggests limited inheritance from parental breeds. Heterozygosity was highest in Red-and-White Holsteins (84.6 %) and lowest in F1 (67.7 %). For the Am-1 locus, the B allele frequency in F1 (0.712) aligned closely with Simmentals (0.806), due to Am-1 BB homozygotes (45 %) and Am-1 BC heterozygotes (53 %), while Holsteins showed a higher Am-1 C frequency (0.570). No significant differences were observed for Cp, with F1 and F2 occupying an intermediate position. The Hb locus exhibited a low Hb B frequency (0.018–0.028), with no polymorphism in Holsteins. High PN-H phenotype activity (0.25) was characteristic of Simmentals. Cluster analysis grouped Simmentals and crossbred offspring into one cluster, separating them from Holsteins. Genetic distances (per M. Nei) indicated a convergence of F1 and F2 gene pools with Holsteins. Similarity with Simmentals persisted due to Tf D2, low Am-1 C frequency, and stable Hb heterozygosity. Gene pool transformation is locus-specific, and “blood share” does not always reflect genetic changes.