FUNCTIONAL ANALYSIS OF LITTING SIZE AND NUMBER OF TEATS IN PIGS: FROM GWAS TO POST-GWAS

Reproductive traits, such as number of teats and litter size, are essential for animal breeding programs due to the importance for the production chain, since they influence the maternal ability of sow and can affect the number of weaned piglets. Our objective was to identify candidate genes associated with reproductive traits in pigs, using GWAS data from a systematic review combined with sequencing data, to build networks of biological processes and TFs (transcription factors) from the identified genes, in order to highlight the most candidate genes for litter size and number of teats. In the systematic review only peer-reviewed articles were used, with descriptors related to the evaluated traits, and selected based on eligibility criteria. Fourteen papers were selected and classified into groups for functional analysis of gene networks with 2,077 candidate genes identified. After combining with the list of genes presenting known structural variants in the 5'UTR and/or coding region, 306 genes remained to be used to build the networks of biological processes and TFs genes, highlighting processes associated with litter size (e.g., ionotropic glutamate receptor signaling pathway and blastocyte growth) and number of teats (e.g., growth hormone receptor, regulation of the BMP - Bone Morphogenetic Proteins signaling pathway and blood vessel proliferation). Two most candidate genes for litter size trait (GRID2 and PALB2) and six most candidate genes for number of teats (GHR, IFT80, FSTL3, SKOR1, SMURF1 and AKT3) were prioritized. TFs associated with candidate genes were also identified for litter size (PALB2 and GRID2) and number of teats (RIN, LTBP2 and COL6A6). Thus, it is suggested that the most candidate genes and TFs presented in this study may play an important role in the traits studied, being important for genetic studies and animal breeding.