Pierce, Courtney F., authorThomas, Milton, advisorSpeidel, Scott, advisorColeman, Stephen, committee memberEnns, R. Mark, committee memberMeiman, Paul, committee member2019-06-142019-06-142019https://hdl.handle.net/10217/195272Beef cattle are drawn to areas with gentle terrain, which may result in heavy grazing near riparian zones and minimal grazing on rugged terrain. Traditional management tools to improve grazing distribution can be costly; therefore, genomic selection has been proposed as a means of improving beef cattle grazing patterns. The objective of this thesis was to identify single nucleotide polymorphisms (SNP) associated with beef cattle terrain-use in the western U.S. Variant detection using RNA-sequencing data obtained from Angus cardiovascular tissues and Brangus reproductive tissues revealed 48 potential causative mutations in five genes that were previously associated with terrain-use indices: SDHAF3, RUSC2, SUPT20H, MAML3, and GRM5. In an additional study, Bayesian multiple-regression was performed using BovineHD genotypes and global positioning system (GPS) data collected from 80 beef cows managed in Arizona, Montana, and New Mexico. Results of this analysis suggested that beef cattle terrain-use was polygenic; however, additional observations were needed to validate the quantitative trait loci (QTL) identified. Subsequent genome-wide association studies (GWAS) were performed for six terrain-use traits using BovineSNP50 genotypes and distribution data collected from a multi-breed population of cattle (n = 330) managed in the western U.S. These analyses identified 32 QTL and 29 putative candidate genes with diverse functions related to hypoxia, heat stress, feed efficiency, weight traits, energy metabolism, and lactation. In conclusion, results presented in this thesis suggested that terrain-use is polygenic and may be improved with genetic selection; however, additional studies are needed to further elucidate the genetic mechanisms underlying terrain-use of beef cattle.born digitalmasters thesesengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.grazing distributionQTLterrain-useGWAScattleSNPText