Genome-wide discovery of underlying genetic factors associated with fresh and frozen-thawed semen traits in composite ram breeds exhibiting different cryosensitivity

Abstract

There are fewer studies investigating the effects of underlying genetic factors related to semen characteristics, which significantly affect sheep farm profitability. This study represents the first Genome-Wide Association Study (GWAS) comparing the genetic backgrounds of two composite sheep breeds with high (Hasmer) and low (Hasak) cryotolerance. To unravel the genetic background of cryotolerance parameters, semen was collected from rams via an artificial vagina and cryopreserved in 0.25 ml straws during the breeding season. Quality characteristics were determined in fresh, equilibrated, and frozen-thawed semen. Despite identical management and climatic conditions, the freeze-thawing process had a more pronounced negative effect on ram semen traits in Hasak than in Hasmer. The conducted GWAS aimed to unveil the genetic structure that might be attributed to cryotolerance, resulting in the identification of 27 single nucleotide polymorphism (SNP) positions influencing post-thaw semen parameters. Moreover, network analyses revealed pathways related to sperm ion channels and their activities, providing insights into the intricate molecular mechanisms underlying sperm physiology and emphasizing their role in potentially impacting sperm cryotolerance. The functional significance of the detected SNPs and their associated pathways requires further exploration.