Allelic Variants of BoLA-DRB3 and Technological Properties of Milk in Cheese and Butter Production

Allelic variants of the BoLA-DRB3 gene affect the parameters that determine the suitability of milk for cheese and butter production. This article introduces a molecular genetic and physicochemical analysis of samples from Russian Black Pied cows. Genotyping at the BoLA-DRB3 locus, performed via PCR-RFLP, revealed fifty-five alleles, with dominant 1101 (15.8%) and 1501 (15.5%). Alleles 0902 (OR = 0.11; p = 0.00014), 1101 (OR = 0.38; p = 0.0047), and 0601 (OR = 0.31; p = 0.0055) were recognized as protective against subclinical mastitis (somatic cell count ≤ 400,000/ml). Conversely, 1501 (OR = 5.48), 1801 (OR = 5.48), and 0701 (OR = 6.62) were identified as risk alleles. Each additional S-allele in the genotype reduced the chances of low somatic cell count by 4 times (p < 0.0001). The animals with high somatic cell count (> 400,000/mL) demonstrated a significantly (p < 0.001) reduced milk yield, as well as fat and protein content and heat resistance. Heat resistance showed a strong negative correlation with the somatic score (p = –0.78). It decreased by 0.58 min for every 100,000/mL increase in the somatic cell count. The integral milk quality index was highest in the carriers of protective alleles (R/N class; 0.621) and 60% lower in the animals with risk alleles (S/N; 0.388). Elevated somatic cell count was associated with lower cheese yields due to protein loss in the whey, impaired rennet coagulation, and deteriorated rheological properties of the curd. Furthermore, increased proteolysis led to bitterness and a shorter shelf life. In butter production, such milk provokes rancidity and poor butter storage stability. Marker-assisted selection for BoLA-DRB3 can improve the technological properties and the economic efficiency of milk production, ensuring high-quality products with long shelf lives.