Abstract: Semen cryopreservation is a core support of the dairy goat breeding system and is important for the long-term preservation,remote sharing and genetic improvement of elite germplasm. However,cryopreservation of dairy goat semen still faces many bottlenecks and lacks a standardized system. This review summarized research progress in five areas:freezing-injury mechanisms,cryoprotectants,extender formulation,freezing-thawing procedures,and emerging auxiliary technologies. Dairy goat sperm are highly sensitive to low-temperature stress,ice-crystal formation,oxidative stress and osmotic fluctuation owing to their high polyunsaturated-fatty-acid content and low cholesterol/phospholipid ratio,and ferroptosis is the predominant form of regulated cell death during cryopreservation. Glycerol remains the main permeable cryoprotectant and egg yolk the main non-permeable component,while new antioxidants and ferroptosis-targeting strategies can mitigate injury. Extenders have been optimized for pH,osmolality,energy substrates and antibacterial strategies,and the equilibration,cooling and thawing steps have been improved. Vitrification,nanotechnology and antifreeze proteins show potential but remain exploratory. Key problems include the lack of a standardized system,the high cost of egg-yolk substitutes,and the difficulty of scaling up emerging and ferroptosis-targeting technologies. Future work should deepen the molecular mechanisms of freezing injury and advance standardization and industrialization.

Key words: dairy goat, semen cryopreservation, freezing injury, ferroptosis, cryoprotectant