Genomic selection for feed efficiency traits in Nellore cattle

Abstract

Animal feeding is the item of the greatest economic importance on beef production systems. This item is responsible for the largest variable cost in the industry and decisive economic efficiency of beef cattle. Selection for feed efficiency was relegated to the background due mainly to high costs of measuring individual consumption and high correlation with weight gain rates. Therefore, genomic selection based on SNP markers for residual feed intake (RFI) can be quite promising, taking into account that the cost of genotyping of animals is reduced. However, there is still no consensus among researchers regarding the most appropriate methods for genomic predictions. Thus, the present study will be developed with the aim of comparing two evaluation methodologies for genomic evaluation for CAR, using high-density chips (approximately 777,000 SNPs, Illumina BovineHD Beadchip). Genomic evaluation for the animals will be conducted using two procedures: single-step - using the inclusion of genomic array of genotyped animals corrected by the genomic relationship matrix of animals not genotyped, and multiple steps - which consists of three steps: a) assessment using traditional genetic animal model, b) estimate the genomic effects for animals genotyped, and c) estimates of genomic values obtained via a selection index. That index is formed by an average of estimated breeding values (EBV) of parents, obtained from traditional genetic evaluation, genomic solutions obtained in the second step and EBVs based on genomic information of genotyped animals. With the results one can determine the most appropriate evaluation method for obtaining genomic values for traits associated with feed efficiency.