Current perspectives on ruminant sperm freezability: Harnessing molecular changes related to semen quality through omics technologies

Abstract

The recent advances in sperm cryopreservation transcend cryobanking and other assisted reproductive technologies. Since its discovery, cryopreservation has contributed positive impacts on animal breeding as well as in genetic exchange, improvement, and conservation efforts. However, cryoinjury and variabilities in cryopreservation outcomes remain as key challenges to sperm cryobiology. The present work explored the molecular bases for such freezability differences and freezing-thawing injuries in the ruminant sperm. Relevant biomarkers identified in the seminal plasma and the spermatozoa were highlighted, including lipids, proteins, metabolites, transcripts, and genes. Specific molecular mechanisms concerning sperm structures and functions were also examined relative to their association to cryotolerance, and spermiogram or seminogram modifications following cryopreservation procedures. Current conflicts and gaps in the knowledge base on ruminant spermatozoa were also emphasized. Further investigation of these areas using the available breakthrough molecular tools such as omics technologies is therefore proposed to improve, optimize, or even predict the overall quality of frozen-thawed ruminant semen towards reproductive efficiency.