Polymorphism of TLR4 and TNF-α genes associated with cattle hoof health

In dairy cattle breeding, hoof pathologies, including laminitis, cause significant economic damage, which necessitates the development of molecular genetic methods for prevention. In cattle, the TLR4 → TNF-α relationship plays a central role in the development of laminitis and hoof dermatitis. The aim of our study was to investigate the polymorphisms of the TLR4 (c.9421C/T) and TNF-α (-824 A/G) genes in 147 Holstein first-calf heifers of Lenin Breeding Farm of the Republic of Tatarstan. The PCR-RFLP method revealed a balanced distribution of the TLR4 gene alleles (A – 0.473, B – 0.527) with high heterozygosity (51.0%). The TNF-α gene showed a dominance of the G allele (0.816) was established with a low proportion of heterozygotes (29.9%). Both genes were in Hardy-Weinberg equilibrium (χ² = 0.084 and χ² = 0.001, respectively), and the inbreeding coefficient (Fis≈0) indicated the absence of inbreeding. Analysis of complex genotypes of the TLR4/TNF-α genes revealed the prevalence of AB/GG (32.65%) and BB/GG (20.41%) combinations, while rare genotype combinations (AA/AA, AB/AA) occurred with a frequency of 0.68%. No statistically significant deviations were found between the observed and expected distributions (χ² = 8.70 with χ²crit = 9.49). The data obtained indicate the genetic biodiversity of the population and can be used to develop programs for breeding animals with increased resistance to metabolic disorders of the hoof apparatus. Identification of associations of polymorphic variants of TLR4 and TNF-α with a predisposition to laminitis opens up prospects for creating a scientifically based system for the prevention of limb pathologies in dairy cattle based on molecular genetic markers.