Yak (Bos grunniens) is a unique bovine species and considered as lifeline of highlanders. The male subfertility in yak is a matter of concern that causes huge economic loses. The spermatogenesis and male reproduction machinery are critically governed by Y-linked genes which tend to acquire necessary information in the course of evolution. The Y-linked fertility genes are present in multiple copies with testis-limited expression. To understand this novel complexity, 12 male-specific region of Y chromosome (MSY) genes have been studied in the yak. Targeted genes are amplified in male and female genomic DNA and confirmed the male derived specificity. Moreover, testis and sperm-specific expressions of MSY genes are distinct among different tissues. The quantitative polymerase chain reaction results validate the expression pattern of these genes in various tissues with predominant expression intestis and sperm. The sequencing of resultant yak MSY genes gives significant result and shows similarity with cattle (Bos indicus), but few nucleotide mismatches define the proposition of infertile male in the F₁ hybrid of cattle and yak. The identified MSY genes can be used to establish male-specific characteristics and to differentiate male and female yak genotypically. Further, these genes may act as valuable resources to understand the capacity of spermatogenesis, embryogenesis, cellular growth, azoospermia and malesubfertility in the yak.

Male fertility in farm animals is considered as an important economic trait. The phenomenon of spermatogenesis plays adynamic functional role in determining the viability of sperm and thereby can impact on fertility-driven complications. The process ofspermatogenesis is controlled by numerous molecular factors and requires a precisely regulated pattern of gene expression. The role ofsmall noncoding RNAs in altering gene expression has been extensively studied. However, limited information is available apropos theirrole in yak spermatogenesis. The present study aimed to evaluate the assessment of some significant microRNAs and their expressionpattern in the body tissues and sperm of fertile and subfertile yak from Arunachal Pradesh besides identified a novel class of sperm enrichedsmall RNA ‘mature-sperm-enriched small RNA’ (mse-tsRNA) in Yak spermatozoa. The RNAwas extracted from tissue and sperm using 27gauge needles and subsequently reverse transcribed into small RNA cDNAs. The PCR positive sperm-predominant miRNAs were validatedby quantitative reverse transcriptase PCR (qRT-PCR) for their expression in fertile and subfertile yak. Of the 22 microRNAs, themiRNA19a, miRNA142 and miRNA143 showed higher expression in the subfertile yak, whereas expression of miRNA7d, miRNA23a andmiRNA23b were found elevated in the fertile animal. The presence of these small noncoding RNAs in yak sperm and testis indicated thelegitimate involvement of their role in yak bull fertility.