Abstract:In the semen cryopreservation of Tongcheng boars,it was found that there were individual differences in semen quality after cryopreservation. According to the results of sperm motility after repeated semen cryopreservation and the pedigree relationship,three individuals with good semen freezability (GSF) and three individuals with poor semen freezability (PSF) were selected,respectively. Fixation index (FST) analysis of GSF and PSF was performed by using the "Zhongxin No.1" SNP chip,and the key candidate genes influencing the semen freezability were identified by bioinformatics method. The results showed that there were significant differences in sperm motility of 22 Tongcheng pigs after cryopreservation. The pedigree relationship among three GSF or three PSF was closer than that between them,which indicated that the differences of semen freezability in boar might be affected by genetic factor. After FST analysis,the mean value of FST was 0.170 5,which indicated a high degree of genetic differentiation between GSF and PSF. Furthermore,266 SNPs in the top 1% of FST (FST>0.53) were selected. By annotating the 100 kb flank regions of these SNPs,we found 397 candidate genes,which enriched in the gene ontology (GO) terms related to cell morphology,actin cytoskeleton and ion channel,etc. Some highly differentiated genes in these biological processes such as KCNG4, ARPC1B, DNAAF4, MNS1, LIMK2,RPL31 and VIM were identified as key candidate genes. These results indicate that semen freezability of boar after cryopreservation is affected by genetic factor and controlled by some key genes,which are worthy of further study.