CYTOGENETIC BIOMARKERS OF REPRODUCTIVE AGING: TELOMERE LENGTH AND CHROMATIN INTEGRITY IN SPERMATOZOA AND LEUKOCYTES OF FARMED DEER

Telomeres play a critical role in maintaining chromosomal integrity and are increasingly recognized as indicators of biological aging and reproductive competence in mammals. However, information on telomere dynamics in cervids remains scarce. This study examined leukocyte telomere length (LTL) and sperm telomere length (STL) as markers of reproductive aging in three deer species.Blood and semen samples were obtained from twenty-seven breeding stags (nine per species) aged 3-11 years. Telomere length was quantified using quantitative PCR and expressed as T/S ratios. Semen was evaluated for volume, sperm concentration, motility, kinematic characteristics, and chromatin condensation, while oxidative status was assessed using d-ROMs and biological antioxidant potential assays. Associations among telomere length, age, semen characteristics, oxidative markers, and species were analyzed using nonparametric tests, multivariate regression, and principal component analysis.Leukocyte and sperm telomere lengths were strongly correlated (p = 0.94, p < 0.001). Both parameters showed a marked age-related decline, with reductions in STL occurring earlier than those in LTL. Sperm telomere length exhibited strong positive associations with semen volume, sperm concentration, and chromatin condensation (all p < 0.001). Significant interspecies differences were detected for STL and semen volume, whereas systemic oxidative stress indicators were not associated with telomere length.