Detection of Candidate Genes Associated with Fecundity through Genome-Wide Selection Signatures of Katahdin Ewes

SIMPLE SUMMARY: It is difficult to improve the reproductive performance of sheep (fecundity, fertility, and prolificacy) through the simple selection of animals that are outstanding due to phenotype. The genetic transmission of the reproductive performance to progeny is of low effectiveness for these types of traits, which is why traditional selection has not been successful. Presently, there is scarce information about the reproduction of Katahdin sheep and apparently no information about genes associated with reproductive traits. In this study, a genetic scan was conducted to detect genes associated with fecundity in Katahdin ewes. It was found that genes expressed in reproductive tissues tend to be reported frequently as candidates; that is, they are genes that directly influence the fecundity of ewes: CNOT11, GLUD1, GRID1, MAPK8, and CCL28. Other genes have indirect influence, for example, those that affect hormonal processes such as lipid synthesis: ADIRF, CCL28, and HMGCS1. New genes associated with the fecundity of Katahdin ewes are reported in this study. ABSTRACT: One of the strategies to genetically improve reproductive traits, despite their low inheritability, has been the identification of candidate genes. Therefore, the objective of this study was to detect candidate genes associated with fecundity through the fixation index (F(ST)) and runs of homozygosity (ROH) of selection signatures in Katahdin ewes. Productive and reproductive records from three years were used and the genotypes (OvineSNP50K) of 48 Katahdin ewes. Two groups of ewes were identified to carry out the genetic comparison: with high fecundity (1.3 ± 0.03) and with low fecundity (1.1 ± 0.06). This study shows for the first time evidence of the influence of the CNOT11, GLUD1, GRID1, MAPK8, and CCL28 genes in the fecundity of Katahdin ewes; in addition, new candidate genes were detected for fecundity that were not reported previously in ewes but that were detected for other species: ANK2 (sow), ARHGAP22 (cow and buffalo cow), GHITM (cow), HERC6 (cow), DPF2 (cow), and TRNAC-GCA (buffalo cow, bull). These new candidate genes in ewes seem to have a high expression in reproduction. Therefore, future studies are needed focused on describing the physiological basis of changes in the reproductive behavior influenced by these genes.