Association of A80V, R25C, AND Y7F leptin gene sites with productive longevity duration in Kholmogory cows

In modern dairy farming, the study of genetic factors affecting the productive longevity and milk productivity of cattle is relevant. The leptin gene, involved in the regulation of energy metabolism, is a promising marker for selection. However, the influence of its polymorphism complex genotypes (A80V, R25C, Y7F) on the productivity and longevity of animals has not been sufficiently studied, which determines the importance of this research. The aim of the study was to investigate the influence of the leptin gene complex genotypes at sites A80V, R25C, Y7F on the milk productivity indicators and the duration of economic use of Kholmogory cattle. The study was conducted on 207 Kholmogory breed cows, divided into groups with different complex genotypes. For statistical analysis, the number of animals in the compared groups was equalized: 13 heads per group for the study of lifetime milk productivity and 19 heads per group for the assessment of the duration of use. Genotyping was performed by PCR-RFLP, and statistical processing was carried out using non-parametric methods (Mann - Whitney U test). Lifetime daily milk yield, milk fat and protein content, age at culling, and lifetime milking days (LMD) were analyzed. It was revealed that the AVRCYY genotype is associated with the maximum daily milk yield (22.04 kg) and the highest number of LMD (2032 days), indicating its positive influence on productive longevity. The lowest indicators were noted for the AVCCYY genotype (194 LMD). Significant differences in milk fat content were found between groups AACCYY, AARCYY, AARRYY, and AVCCYY. The AACCYY genotype showed the highest protein content (3.23%), but the lowest milk yield. Differences in the structure of culling reasons were also identified: gynecological diseases prevailed in animals with the AVCCYY genotype combination, while limb diseases prevailed in animals with the AVRCYY complex genotype. The results of the study demonstrate the significance of a comprehensive analysis of leptin gene genotypes for dairy cattle selection. The AVRCYY genotype can be recommended as a marker for increased productive longevity.