Application Of Genomic Selection On Carcass And Meat Quality Traits In Simmental Cattle

Duing to decreasing the generation interval and increasing genetic progress, genomicselection has received widespread attention in the field of animal genetic breeding and has becomeworldwide research focus for the worid’s breeders. With completion of the bovine genomesequencing and appearance of high-density SNP chip (e.g. the Illumina BovineSNP50(54k) andIllumina BovineHD (770K)), GS can study in beef cattle.Experimental animals consisted of621young Simmental bulls, born in2008to2010,originated from Ulgai, located at Xilingol league, Inner Mongolia, China.136young bulls born in2008, were genotyped with IlluminaBovineSNP50. Additionally,504young bulls were genotypedwith The Illumina BovineHD chip. Carcass traits and meat traits were analyzed in this study,carcass traits included live weight, carcass weight, rib eye muscle weight and tenderloin weight;meat traits included shear force and rib eye muscle area.This thesis contained two main parts: single trait genomic selection and multiple traitsgenomic selection. In the first part study, three methods (GBLUP, BayesA and BayesB) werepresented to estimate genomic breeding values on six target traits, plotted the marker effectsprofile of six target traits in Simmental cattle population, and evaluated the effect of markerdensity on accuracy of GEBV. Results showed that the accuracy of GEBV of carcass traits andmeat traits ranged from0.69to0.86. BayesB method had more accuracy of GEBV on carcasstraits, moreover BayesA method showed the advantage on meat traits. In GBLUP, accuracy ofGEBV was highest when50000~100000SNPs were used to construct the genomic relationshipmatrix. In BayesA and BayesB, they have better performances in estimating breeding values whencontained more markers.Multiple traits genomic selection was the second part. In this study, six target traits weredivided into five groups, each group contained two traits. Two methods (mtGBLUP andmtBayesA) were used to estimate genomic breeding values on five group data. Results showedthat the accuracies of GEBV using multiple trait model on the live weight, carcass weight, rib eyemuscle weight and tenderloin weight traits had increased, comparied with single trait model.However, the accuracies of GEBV had significant reduction on shear force and rib eye musclearea.