Vitamin C (Ascorbic Acid) Supplementation in Caprine Semen Extenders: Current Evidence, Knowledge Gaps, and Implications for Triladyl® Based Preservation Systems

Cryopreservation of goat semen is an essential tool for genetic improvement, germplasm conservation, and the expansion of artificial insemination programs in caprine breeding. However, buck spermatozoa are highly susceptible to cryo-induced oxidative stress due to their membrane composition rich in polyunsaturated fatty acids. Excessive generation of reactive oxygen species during semen processing, freezing, and thawing compromises sperm motility, viability, membrane integrity, mitochondrial function, and DNA stability, ultimately reducing post-thaw fertilizing potential. Semen extenders play a pivotal role in mitigating these detrimental effects by providing cryoprotection and maintaining cellular homeostasis. Among commercial extenders, Triladyl® is widely used in ruminant semen preservation; nevertheless, its intrinsic antioxidant capacity appears limited, necessitating further optimization strategies. Vitamin C (ascorbic acid), a potent water-soluble antioxidant naturally present in seminal plasma, has attracted considerable attention as an extender supplement due to its ability to scavenge reactive oxygen species and regenerate other antioxidants. This review critically synthesizes published evidence on vitamin C supplementation in semen extenders, with particular emphasis on its relevance to Triladyl®-based preservation systems in goats. Although direct studies evaluating vitamin C in addition to Triladyl® in caprine semen are scarce, substantial indirect evidence from Tris-based extenders, comparative extender studies, and cross-species investigations supports its potential to enhance post-thaw semen quality. The review also highlights current limitations, including variability in experimental designs, dose-dependent effects, and the lack of extender-specific data. Overall, the current literature supports vitamin C supplementation as a promising hypothesis that warrants systematic evaluation in commercial extender systems.