Genetic evaluation in the presence of genotype-environment interaction in Nellore cattle: Application of genomic tools

Abstract

Some studies have shown existence of differentiation among biotypes and opened a perspective to promote increments in the meat production chain, allowing the selection of animals with appropriate profile to the objectives of different properties. However, there are no studies considering the biotypes in different environments and using genomic information to identify regions associated with phenotypic manifestation of the biotypes. Thus, this project aims identifying the most appropriate biotype of Nellore cattle for different environments, by principal component analysis and reaction norm models; to identify genomic regions associated with the phenotypic expression of different biotypes in different environments; and to evaluate the predictive ability of genomic selection for the different biotypes in different environments. Data from Aliança Nelore will be used, comprising information of approximately 500,000 animals at weaning and 330,000 at yearling, which were born between 1984 and 2014. The phenotypes of nine traits will be considered: birth-to-weaning gain, and visual scores of conformation, finishing precocity and muscling at weaning, weaning-to-yearling gain, and visual scores of conformation, finishing precocity and muscling and, scrotal circumference at yearling. The reaction norm model will be applied first; later, the principal component analysis will be applied to the different gradients, using as original variables the EBVs of the principal components, where biotypes will be characterized by the eigenvectors of the components and then these EBVs will be used in genome-wide association and genomic prediction studies.