The identification of litter size related single nucleotide polymorphisms from differentially regulated genes of early embryo in Landrace sows

Reproductive traits, especially litter size, are important components for reducing the costs of pig production. DNA molecular markers can be used for marker-assisted selection (MAS) program through candidate gene approach to improve the rate of selection response. Landrace is the major strain of sow used in commercial pig production in Taiwan but there is no available molecular marker associated with purebred Landrace.he survival and proper development of early embryos are important factors affecting the reproductive traits of sows. The purpose of this study is to discover the SNPs located on the regulatory regions of differentially expressed genes between morula and blastocyst. We also characterized the SNP genotypes of these genes and studied the association of litter size with these genotypes in Landrace sows. fter cloning and sequencing regulatory region of the 10 candidate genes in 30 Landrace sows, we found 59 novel SNPs. Furthermore, we genotyped the SNP markers within the candidate genes in 161 Landrace sows. The effects of SNP markers on total number of pigs born (TNB) and number born alive (NBA) were tested. Our results showed the SNPs located on ataxia-telangiectasia mutated (ATM) gene, plasma platelet-activating factor acetylhydrolase (plasma PAFAH) gene and prolactin (PRL) gene were associated with TNB and NBA (P < 0.05). As most of these SNPs located on the regulatory sequences of the candidate genes, they may have direct effects on regulating expression levels of those genes. We therefore propose ATM, plasma PAFAH and prolactin, the host genes for litter size related SNPs, are likely to have major effects on litter size in pigs, and these efforts may help us to improve the reproductive efficiency of pigs. We developed an efficient and effective platform based on litter size related SNPs associated with the regulatory sequences of differentially regulated genes from morula to blastocyst preimplantation embryos. Once validated further with larger sample size from multiple farms, this SNP based screening platform will significantly facilitate the selection of best breeding herd of Landrace sow.