Sperm Cryopreservation Techniques in Domestic and Wild Ruminants

Sperm cryopreservation underpins both livestock breeding and the conservation of endangered ungulates by safeguarding genetic diversity and enabling artificial insemination programmes. Core methods include controlled-rate slow freezing and ultra-rapid cooling (vitrification), each tailored to balance intracellular dehydration against ice crystal formation. Extenders composed of buffers, sugars and proteins combine with permeable and non-permeable cryoprotectants—such as glycerol, sucrose or soy lecithin—to stabilise membranes and reduce osmotic shock. Species-specific factors influence protocol efficacy: domestic sheep and goats often exhibit greater sensitivity to cooling rates than their wild counterparts (mouflon, ibex), while ram ejaculates display marked individual variability in freezability. Key quality metrics encompass post-thaw motility, viability, acrosome and mitochondrial membrane integrity, and DNA fragmentation. Recent advances address optimised cooling curves, novel extender formulations and biomarker discovery (notably aquaporin expression) to predict and enhance cryoresistance. These developments have global significance, supporting intensive breeding operations, wildlife recovery initiatives and transboundary semen exchange under strict regulatory frameworks.

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Sperm Cryopreservation Techniques in Domestic and Wild Ruminants publication trend

The graph below shows the total number of articles in sperm cryopreservation techniques in domestic and wild ruminants across all publications each year (not limited to Nature Index journals).

Technical terms

Cryopreservation: Preservation of cells at very low temperatures to halt metabolic activity and loss of function.

Slow freezing: Gradual cooling method that permits controlled dehydration of cells, reducing intracellular ice formation.

Vitrification: Ultra-rapid cooling technique that solidifies fluids into a glass-like state without ice crystal growth.

Cryoprotectant: Chemical agent (permeable or non-permeable) added to extenders to protect cells from osmotic and ice-induced damage.

Aquaporin: Membrane protein channel that mediates water and small solute transport, influencing sperm cell osmotic balance and cryotolerance.

References

1. Ultra-rapid cooling of ibex sperm by spheres method does not induce a vitreous extracellular state and increases the membrane damages. PLOS ONE (2020).
2. Sperm Response to in vitro Stress Conditions in Wild and Domestic Species Measured by Functional Variables and ROS Production. Frontiers in Veterinary Science (2021).
3. Variation of existence and location of aquaporin 3 in relation to cryoresistance of ram spermatozoa. Frontiers in Veterinary Science (2023).