2012 Annual Report 1a.Objectives (from AD-416): 1) Increase the resolution of the sheep linkage map. 2) Identify genomic region(s) associated with phenotype(s) relevant to sheep producers. 1b.Approach (from AD-416): Blood or tissue samples have been collected and stored for all sheep breeds at the U.S. Sheep Experiment Station (USSES). DNA will be extracted from samples of a subset of related animals. Genotypes will be generated using the Ovine SNP50 BeadChip. Pedigree data will be analyzed with the genotypes to improve the ovine linkage map resolution. Generating Ovine SNP50 BeadChip genotypes will create the opportunity to perform genome-wide association studies. Thus, production-relevant sheep phenotype(s) will be evaluated with the genotypes to determine whether the phenotype(s) are statically associated with region(s) of the sheep genome. 3.Progress Report: To improve the chromosomal position of markers on the sheep linkage map and increase marker density. USSES contributed sheep DNA samples for genotyping with the ovine SNP50 marker set and pedigrees of the genotyped sheep. This information will improve marker density and refine marker position. Overall, this data will improve scientists' ability to identify genes, underlying quantitative-trait loci (QTL), and improve map comparisons between sheep and humans, cows, swine, etc. This collaboration addresses Subojectives 1.A, "Evaluate different terminal sire breeds for survival, rate and efficiency of growth, carcass composition, and meat quality in extensive western management systems" and Subobjective l.B, "Evaluation of Romanov crossbred, Polypay, and Rambouillet ewes as maternal lines in a terminal crossbreeding system" of the related in-house project. Improving the ovine linkage map will increase the probability of scientists identifying markers for marker assisted selection to improve sheep production.