Cryopreservation of Yak Semen: A Comprehensive Review

SIMPLE SUMMARY: The yak is a multifunctional domesticated mammal that serves as a protein source for local herders and as a cultural and religious symbol. Recent worldwide climatic changes, namely, global warming, have directly impacted yak habitats; specifically, they have negatively influenced yak population sizes, as natural reproduction is not adequate to maintain a stable population. These conditions have caused researchers to investigate artificial yak reproduction. In this review, we cover numerous features of sperm cryopreservation in yaks and the many research efforts undertaken to enhance the cryopreservation process in yaks. ABSTRACT: An urgent need to boost the sustainability and efficiency of animal production exists, owing to the growing global population. Enhancing the global fertility of animals, especially cattle, is essential to ameliorate this issue. Artificial insemination and sperm cryopreservation have a considerable and favorable influence on the quantity and quality of the cattle produced. Sperm cryopreservation is crucial for livestock production because it promotes and accelerates genetic diversity and the worldwide dispersion of animals with enhanced genetics. Owing to the importance of cryobiology in reproductive technologies, researchers are developing new approaches, and they are testing cryoprotectant drugs to enhance sperm cryosurvival. However, the viability of sperm after freezing is low and widely varies across breeding yaks. These faults are crucial because they impede advances in reproductive biotechnology and the study of mammalian gametes at a fundamental level. Using chemicals, researchers have developed and enhanced various extenders with varying degrees of efficiency to reduce cryodamage and oxidative stress. In this article, we review the cryopreservation of yak semen, the development of extenders, the difficulties faced during cryopreservation, and the evaluation of semen quality using various methodologies. This review might be helpful for researchers exploring semen cryopreservation in the future, as demand for enhanced cryopreservation exists to boost the post-thaw viability and fertility of sperm.