Genetic Regulation of Reproduction Traits in Livestock Species

Reproduction traits are economically important traits in the livestock farming industry. As complex traits, reproduction traits are affected by genes, reproductive disease, and environmental factors. Generally, reproduction traits have low to medium heritability. Phenotypic selection for these traits typically has an unnoticeable response. The inclusion of molecular markers such as SNPs associated with reproduction traits could efficiently enhance the selection response. Therefore, knowledge of the underlying genetic regulation and identification of causal genetic variants of reproduction traits would be conducive to not only improving breeding efficiency but also helping us to better understand animal development and regulate animal reproductive ability.

Various approaches such as quantitative trait loci (QTL), genome-wide association study (GWAS), and selection signature analysis have been applied to identify genes and variants associated with reproduction traits. The development of high-throughput sequencing technologies helps us screen candidate genes and variants rapidly. Furthermore, integrating high-throughput sequencing information from genomics, transcriptomics, proteomics, and other related fields (e.g. metabolomics) contributes to analyzing the complex interactions within biological systems and then identifying the causal genes and variants more efficiently. Many variants were used as
markers in molecular marker-assisted selection and genomic selection. The biological function of some genes and variants is well verified. Moreover, genetic engineering of livestock using methods such as CRISPR is also an effective way for the genetic improvement of reproductive traits. Identification of genes with clear biological functions would be good targets for genetic engineering.

This topic welcomes research on the genetic regulation of reproduction traits in livestock species. The original research articles can cover, but are not limited to, the following areas of
research:

• Mapping of quantitative trait loci (QTL) and Genome-wide association study (GWAS)
• Candidate gene and variant analysis using high-throughput technologies
• Identification of marker for reproductive ability or reproductive disease resistance
• Gene editing
• Genomic selection