Editorial: Germplasm conservation and semen banking in livestock: strategies, challenges, and applications

The Research Topic "Germplasm Conservation and Semen Banking in Livestock: Strategies, Challenges, and Applications" was therefore conceptualized to provide an interdisciplinary scientific platform addressing these challenges through innovative research in reproductive biotechnology, gamete preservation, embryo cryobiology, molecular fertility regulation, and advanced cryoprotective strategies. The collection specifically aimed to integrate fundamental reproductive biology with practical applications in livestock breeding, artificial insemination, embryo transfer, and conservation programs.The major objective of this Research Topic was to generate scientific knowledge that could improve the efficiency, reliability, and practical applicability of livestock germplasm conservation systems. The Topic focused particularly on:1. Developing innovative cryopreservation approaches for improving post-thaw viability and fertility of spermatozoa, oocytes, and embryos. 2. Understanding molecular, cellular, endocrine, and metabolic mechanisms governing gamete cryotolerance and reproductive performance. 3. Identifying safer and more efficient cryoprotectants capable of minimizing cryoinjury and oxidative stress. 4. Optimizing in vitro fertilization and embryo production systems using preserved gametes and embryos. The study employed an integrative analysis of the hypothalamic-pituitary-testicular (HPT) axis and identified key genes, signaling pathways, and hormonal interactions associated with differences in sperm motility and male fertility. By linking molecular pathways with reproductive phenotypes, the study contributes substantially to the understanding of fertility regulation mechanisms in avian species.Importantly, the knowledge generated from this work has practical implications for livestock breeding and germplasm conservation programs. Identification of fertility-associated genes and molecular biomarkers can support: Marker-assisted selection of breeding males with superior reproductive performance,  Early fertility prediction in breeding programs,  Development of genomic selection tools,  Improvement of semen quality evaluation protocols in poultry species.Such applications are particularly valuable for conserving elite and indigenous avian germplasm, where maintaining reproductive efficiency is essential for sustainable breeding and semen banking programs.Cryoinjury and oxidative damage remain major obstacles limiting successful preservation of gametes and embryos. Addressing these issues was one of the primary objectives of this Research Topic. The article "Research Progress on Novel Bionic Cryoprotectants in Gamete and Embryo Cryopreservation" made a highly significant contribution toward this objective.The review comprehensively summarized recent advances in biomimetic and bioinspired cryoprotectants, including: Antifreeze proteins,  Nanoparticle-based cryoprotectants,  Synthetic polymers,  Naturally derived biomolecules,  Cell membrane stabilizers.These bionic cryoprotectants mimic natural biological defense systems against cold stress and ice crystal formation, thereby reducing cellular injury during freezing and thawing.The article provides a strong scientific foundation for developing safer and more efficient cryopreservation systems with lower cytotoxicity than conventional cryoprotective agents such as glycerol and DMSO. The practical application of this knowledge includes: Formulation of next-generation semen extenders,  Improvement of embryo vitrification protocols,  Reduction of oxidative and osmotic stress during freezing,  Enhancement of post-thaw fertility and embryo survival,  Development of species-specific cryopreservation protocols for endangered livestock breeds.The review also highlights the future potential of integrating nanotechnology and biomimetic materials into livestock cryobiology, which may revolutionize germplasm banking systems globally.Another important objective of the Research Topic was to improve reproductive competence and developmental efficiency of cryopreserved gametes and embryos under assisted reproductive systems. This study therefore contributes directly toward improving the reliability of embryo preservation systems for livestock conservation and genetic improvement programs.Oxidative stress and mitochondrial dysfunction are among the most important causes of sperm cryodamage. Addressing oxidative injury through novel additives and metabolic regulation strategies was another major objective of the Research Topic. The article "Protective Roles of Melatonin Regulated Mitochondrial DNA Methylation and Respiratory Metabolism in Ram Sperm Cryopreservation" contributed significantly toward this area.The study demonstrated that melatonin exerts cytoprotective effects during ram sperm cryopreservation through regulation of: Mitochondrial DNA methylation,  Respiratory metabolism,  Oxidative stress pathways,  Cellular energy homeostasis.The findings showed improved sperm functionality and cryosurvival following melatonin supplementation, highlighting its potential as an effective antioxidant additive in semen extenders.The practical implications of this work are extensive and include: Development of antioxidant-enriched semen extenders,  Improvement of post-thaw sperm motility and viability,  Enhancement of fertility following artificial insemination,  Reduction of mitochondrial damage during freezing,  Improvement of semen preservation protocols for small ruminants and other livestock species.Furthermore, the study advances understanding of epigenetic and mitochondrial regulation during cryopreservation, opening new possibilities for precision cryobiology and fertility preservation research.Collectively, the manuscripts published under this Research Topic successfully fulfill the major objectives envisioned during its conception. The studies integrate molecular reproductive biology, cryobiotechnology, antioxidant research, embryo culture optimization, and biomimetic preservation strategies to address critical limitations in livestock germplasm conservation systems.Importantly, the knowledge generated through these studies can be translated into practical applications such as: Improved semen and embryo banking protocols,