Abstract #W77

# W77
Genome-wide association on growth traits in Nellore Cattle.
Rafael M. O. Silva*1, Daniela A. L. Lourenco2, Breno O. Fragomeni2, Luciana Takada1, Rafael Espigolan1, Maria E. Z. Mercadante3, Fernando Baldi1, Guilherme C. Venturini1, Joslaine N. S. G. Cyrillo3, Lucia G. Albuquerque1, 1Univ Est Paulista Julio de Mesquita Filho–FCAV-UNESP, Jabiticabal, SP, Brazil, 2The University of Georgia, Athens, GA, 3APTA Center for Beef Cattle, Animal Science Institute, Sertaozinho, SP, Brazil.

The purpose of this study was to identify genomic regions which could explain the genetic variation in growth traits in a Nellore cattle population. The data set contained 8702, 8004, 3828, and 3942 records for birth weight (BW), weaning weight (WW), one year weight (YA) and yearling weight (YW), respectively. The animals were genotyped using panels of high-density SNP (Illumina High-Density Bovine BeadChip, 700k). After genomic data quality control, 437,197 SNPs for 631, 635, 342, and 299 animals for BW, WW, YA, and YW, respectively, were also available. SNP solutions were estimated by genome-wide association study using a single-step BLUP approach (ssGWAS). Before the ssGWAS the data was analyzed by a single-step genomic BLUP. Variances were calculated for windows of 200 SNP. Fixed effects in the model included month of birth, age of dam (linear and quadratic effect), contemporary group (sex, year of birth, and pen), plus animal and maternal additive random effects. Moreover, maternal permanent environmental effects were considered as random for all traits but BW. The results showed the top 10 SNP windows for each trait explained a total of 7%, 2.5%, 1.5%, and 3.5% of variance of BW, WW, YA, and YW, respectively. For all of analyzed traits the SNP windows with greatest influences were at chromosome number 14 (BTA14). In all regions of top SNP windows many genes that have been associated with growth in beef cattle were found. Various authors have recommended caution to interpret the results. Even though many SNP windows explained part of variance of all studied traits, it does not necessarily mean those regions cause the phenotypic variation. These results suggest that there are many regions on chromosome 14 associated with growth traits in Nellore cattle. São Paulo Research Foundation (FAPESP) grant 2013/01228-5 associated to grant #2009/16118-5

Key Words: beef cattle, GWAS