Study of associations of KCNB1 gene polymorphism with milk productivity and milk quality with the including “KLYUVER PRO” yeast additive in the diet

High-producing dairy cattle are particularly susceptible to metabolic disorders and nutrition-related diseases, as their physiology is primarily focused on milk synthesis, even in the face of nutrient deficiencies. This is due to the fact that years of selection for milk yield have led to the development of a lactation dominant system, in which the body devotes a significant portion of its resources to milk production, often to the detriment of other systems. Including yeast probiotics, which have the ability to absorb oxygen in the rumen, in the diet promotes the formation of a favorable anaerobic environment for the normal flora of the rumen. Genetic factors play a significant role in the stable establishment of productive traits in cattle. The aim of this study was to investigate the relationship between the KCNB1 gene polymorphism (g.78216220G>A) and milk productivity in Holstein cows fed the probiotic yeast supplement “KLYUVER PRO”, based on Kluyveromyces marxianus yeast strain. The study involved 120 lactating cows, grouped into 60 cows at Lenin Agricultural Breeding Farm in Atninsky District of the Republic of Tatarstan. The experimental group was additionally fed 20 g of “KLYUVER PRO” per cow per day for 60 days. The study revealed that, compared to the control herd, the group of cows with the KCNB1 AA genotype that received the supplement demonstrated an average daily milk yield improvement of 6.94%, milk protein yield of 10.73%, and the sum of fat and protein by 11.32%, including a significant increase in milk fat by 11.86% (p≤0.05). In the same comparison, the herd with the KCNB1 GG genotype outperformed the control herd in average daily milk yield by 5.96%, milk fat by 9.01%, the sum of fat and protein by 8.83%, and significantly exceeded the control herd in milk protein yield by 8.64% (p≤0.05).