448 Late-breaking: GWAS analysis show QTL in horses which are characterized by sperm resistance to freezing

Abstract

Damaging effects of low temperatures on the functionality of sperm is well known. Stallion sperm cryoresistance has a high individual variability. The genetic basis of cryoresistance and its heritability are little studied. The aim of the study was to search for genome-wide associations with sperm motility after freezing. 96 sperm samples were collected. The collected sperm was diluted to a final concentration 100 mln/ml and frozen in 0.5 ml straws or 18–20 ml tubes. The evaluation of semen was carried out no earlier than 24 hours after freezing. Sperm motility was assessed by computer-assisted semen analysis (CASA). Genomic DNA was purified form semen samples and genotyped using Affymetrix Equine HD array. Genotypes quality control and association studies were performed in Plink 1.9 and EMMAX software respectively. Evaluation of sperm motility showed high individual variability in both total and progressive motility after freezing. Total motility varied from 0.5 to 92.5%, and progressive motility from 0.5 to 70.8%. Sufficient associations of PTF with SNP’s were detected on chromosome (Chr) 1 (P < 1.33e-09) and 4 (P < 2.00e-09). Found SNP’s were located in genes PAS domain-containing protein 3 (Chr1) and UBAP1-MVB12 (Chr4). Expression of these genes in human body was found in cerebrum and male genitals. Suggestive SNPs were found lying nearby to genes responsible for formation of cell wall and proteins affecting mitochondrial activity. Performed studies are presenting first step of understanding genetic background of cryoresistancy of semen in horses. Found markers could be used for selection of stallions based on cryopreservation ability. Authors acknowledge financial support from Russian Science Foundation, Grant No: 18-16-00071.

Genome-wide association study for frozen-thawed sperm motility in stallions across various horse breeds

“…Importantly, as one of the key targets of selection, sperm quality and cryotolerance in stallions have a high individual variation that depends on both environmental and genetic factors [ 2 , 3 , 10 ]. To date, horse breeding involves a widespread use of artificial insemination (with the exception of thoroughbred racehorses), and that is why high quality of cryopreserved semen is vital and pivotal [ 3 , 11 , 12 ].…”