Estimation of genotype-environment interaction using genomic reaction norm and analysis of gene network for reproductive traits in Nellore cattle

Abstract

The Brazilian beef cattle are raised predominantly on pasture conditions with a wide range of environments. Animals evaluated in different environments may present diverse responses due to the genotype-environment interaction (G×E). Currently, G×E interactions can be studied with the assist of single-nucleotide polymorphism (SNP), which allows estimating the effects of SNPs and the prediction of genomic breeding values for selection candidates in different environments. Furthermore, the estimation of SNP effects may be used to identify genomic regions that affect the expression of traits in distinct scenarios. Based on this information it is possible to assess candidate genes and biological pathways associated to the traits in each environment. Thus, this study aims to evaluate the genotype-environment interaction using genomic information, seeking to identify the plasticity of genomic breeding values and possible changes of candidate genes and biological pathways associated to reproductive traits in Nellore cattle. The following traits will be considered in this study: age at first calving (AFC), early pregnancy occurrence (OPP), reconception rate (REC) and scrotal circumference (SC). For the evaluation of G × E, a reaction norm approach including genomic information will be adopted. The environmental groups will be defined by farm, year of birth, sex and management group. The inclusion of genomic information in the analysis will be performed using the numerator relationship matrix combined with the genomic matrix. The SNP effects based on each environment will be used to evaluate possible changes of candidate genes as well as the most important biological expression of each trait.