Abstract

Simple SummaryYak is an essential livestock species found on the Tibetan Plateau. Compared to animals that primarily inhabit plains, yak have a unique sperm maturation process tailored to their reproductive needs in high-altitude environments. The cauda epididymis is crucial for sperm development and is susceptible to post-transcriptional regulation by microRNAs (miRNAs). To investigate the regulatory dynamics of yak sperm maturation, miRNAs from this tissue in both yak and cattle were sequenced. A total of 497 miRNAs were identified across the two species. Comparative analysis revealed 31 miRNAs that were differentially expressed between them. Among these, 16 predicted target genes associated with eight miRNAs were found to be potentially linked to the structural or functional maturation of sperm. The expression of some miRNAs was validated, revealing an opposite trend compared to their corresponding predicted target genes. This study provides foundational data and new research perspectives for further understanding the gene regulatory network underlying yak sperm maturation in extreme environments.The yak represents a distinct domestic animal species that predominantly inhabits the Qinghai–Tibet Plateau and adjacent areas, possessing considerable value in both scientific and economic contexts. Compared to animals that mainly dwell on plains, such as cattle, the sperm maturation process in yak exhibits a certain degree of species specificity to adapt to their unique reproductive needs in high-altitude environments. Serving as the main storage site for functionally competent sperm, the cauda epididymis plays an integral role in mediating their post-testicular maturation. MiRNAs are vital regulatory molecules in the epididymis, influencing sperm maturation by modulating gene expression after transcription. To investigate the unique regulatory mechanisms of sperm matura