# Genome-Wide Association Study That Identifies Molecular Markers with Freezing Resistance in Duroc Boar Sperm

## TL;DR

This study identifies genetic markers linked to freezing resistance in Duroc boar sperm, aiding in the selection of better breeding stock for artificial insemination.

## Contribution

The study identifies eight SNPs and four candidate genes associated with sperm freezing tolerance in Duroc boars.

## Key findings

- Eight SNP loci and four candidate genes were found to be significantly associated with sperm freezing tolerance in Duroc boars.
- Dominant genotypes of four SNPs were identified as useful for selecting boars with high sperm freezing tolerance.
- Sperm recovery rates showed considerable individual variation, with better sperm structure in freeze-tolerant individuals.

## Abstract

Frozen semen preservation technology is a key technology in the artificial insemination of livestock and poultry and is of great significance in the development of modern animal husbandry. However, it is well known that the freezing ability of boar sperm varies from individual to individual. Therefore, the identification of molecular markers associated with freezing tolerance represents a promising approach to efficiently selecting boars with superior sperm freezing characteristics. In this study, the sperm recovery rate of 165 Duroc pigs was measured as a trait of freezing tolerance for genome-wide association analysis. Through this research, we identified eight SNP loci and four candidate genes that were significantly associated with sperm freezing tolerance. Furthermore, we determined the dominant genotypes of four SNPs, which can potentially be used to identify Duroc boars with high sperm freezing tolerance. Our study provides references and insights into the molecular markers behind the differences in boar sperm freezability and contributes to the advancement of semen cryopreservation technology.

Semen cryopreservation is a crucial technology in the artificial insemination of livestock and poultry. It not only contributes to the conservation of germplasm resources but also facilitates the cross-regional exchange of high-quality breeding stock. In this study, 165 Duroc boars were selected for genome-wide genotyping, and the sperm freezing/thawing motility ratio (sperm recovery rate) was used as phenotypic data for genome-wide association analysis (GWAS). Considerable individual variations in sperm recovery rates (SRRs) were detected, and the sperm structure after cyropreservation was significantly better in highly freeze-tolerant individuals compared to non-freeze-tolerant ones. The heritability of the SRR was calculated and found to be 0.199 ± 0.158, representing low heritability. Through GWAS, eight single-nucleotide polymorphism (SNP) loci and four candidate genes (SLC10A6, MYRF, GGA1, and UTRN) were identified as being significantly associated with sperm freezing tolerance. Moreover, the dominant genotypes of four SNPs were finally determined to be valuable for identifying individuals with high sperm freezing tolerance. This study reveals the heritability of the sperm recovery rate and identifies molecular markers associated with sperm freezing tolerance in Duroc boars, which is of great significance for accelerating boar genetic improvement and enhancing the economic efficiency of pig breeding industry.