Accuracy of Genomic Prediction for Tick Resistance in Braford and Hereford Cattle

Abstract Text: This work aimed to determine the accuracy and bias of genomic predictions of Braford (BO) and Hereford (HH) cattle genetic resistance to ticks. Repeated 10,673 tick counts were obtained from 3,435 BO and 928 HH cattle from Delta G Connection breeding program. A subset of 2,803 BO and 652 HH samples were genotyped and 41,045 markers remained after quality control. Log transformed records were adjusted by a pedigree repeatability model to estimate breeding values (EBV), subsequently used to obtained deregressed EBV. Data were split into five subsets for cross-validation using k-means and random clustering. Genomic predictions with moderate accuracies (0.38 to 0.60) were obtained by best unbiased linear prediction (GBLUP), BayesB and single step GBLUP indicating that, despite some bias, genomic selection could be used as practical tool to improve cattle genetic resistance to ticks.

Keywords: beef cattle, genomic selection, tick resistance