Genomic wide association study for feed efficiency traits in Nellore cattle breeding programs

Abstract

Feed efficiency traits are directly associated with beef cattle profitability and sustainability. Weight gain, feed consumption, conversion rate and residual feed intake (RFI), for example, are important traits for the selection of efficient animals within the production system, however, with the exception of weight gain, these traits are not considered as selection criteria due to the difficulty in obtaining phenotypes for the same animals. Currently, with the advance of sequencing and genotyping technologies, high-density SNP chips are available on market. These molecular information can be used for genome-wide association studies (GWAS), which allow the identification of genetic variants associated with the trait expression in different populations. Therefore, this project aims to conduct a genome-wide association study for feed efficiency, feed intake, weight gain, residual feed intake, and feed conversion rate in two Nelore populations belonging to two breeding programs: Instituto de Zootecnia (Sertãozinho/SP), and Nelore Qualitas . This project may detect chromosomal regions that are associated with the evaluated traits, aiming to find possible differences or similarities between the populations, and also to evaluate the existence of common candidate genes in both herds. The animals will be challenged in an individual performance test and evaluated for at least 70 days for feed consumption, weight gain, RFI and feed conversion rate. At the end of the test in 2016, we expecte to have a total of 1840 genotyped animals with phenotypic information. The consistency analysis will be performed for each trait, and the variance components will be estimated by using the Single-Step methodology. The animal model will include the fixed effect of contemporary group, fitting the genetic additive direct and residual effects as random. (AU)